Hey Jordan, one minor point. When you use an infrared thermometer like that to measure the temperature of a low emissivity surface (aluminum foil will be about 0.03 emissivity) you need to put a small piece of masking tape on the foil surface and hold the IR thermometer very close to the tape so the only thing in its field of view is the tape. The tape emissivity will be about 0.9. This will allow you to get a much closer temperature reading of the underlying foil. Of course, remove the tape after you take the reading. Otherwise when you aim the IR thermometer at the bare foil surface the thermometer is going to "see" the reflection of the room and that is what the reading will be for. That is because a low IR emissivity equates to a high reflectivity. These IR thermometers are typically calibrated assuming the subject surface IR emissivity is about 0.9.
Good that you're thinking of the emissivity of the surfaces being compared, but I think you're missing the point. Putting tape on the radiant barrier defeats the whole idea. Of course adding tape increases emissivity. That's exactly what the reflective product is trying to avoid - emitting heat. So the way he has done the comparison is correct. That's exactly the point he makes with the foam. If something is touching the radiant barrier, it shortcuts its magical radiant properties. However, some radiant barrier products do have a possible downside in that if they get dirty, they increase their emissivity. They can degrade over time if they are a cheaply laminated product. Look at this same roof in 10 years or 20 years and the emissivity will have increased, for many reasons.
@@seanmaxwell4976 What he's measuring isn't useful, unfortunately. That reflective material is going to reflect both ways; from the sun->roof->radiant barrier, and from the room->radiant barrier->(and back into the room). What he is measuring is some unknown combination of the temperature of the radiant barrier * some emissivity coef + the room temperature + a reflection of his own body temperature. I don't think you can say anything with the result he gets. I bet if he positions himself closer to the barrier, he'd get a higher temperature due to the reflection. I think what he wants to measure is the effective heat flow, and there are two ways I think you could do that. The first is to get a styrofoam cooler without the lid, put a cup of cold water in it, and rest it open side against the radiant barrier / OSB. Take temperature readings every 10 minutes, the delta will give you an idea of the heat flow. You could probably get a reasonably accurate absolute measurement from this experiment. The other way would be to go on to the roof; the temperature of the shingles above the radiant barrier should be hotter than the ones over plain OSB. This isn't as good as the first, but will give you a relative difference. The best thing to do is just figure out what the difference in heat flow due to radiation would be. If you figure the temperature of the radiant barrier / wood is (say) 75 degrees celsius, and the ambient temperature is 50 degrees celsius, and the emissivity is 0.1 for the barrier and 0.9 for the wood, you get something like a heat transfer of 20 watts/meter for the radiant barrier and 200 watts/meter for the OSB. That's a huge difference.
@@fgbhrl4907 Great points and it's fun to think about how to measure properly. There are many difficulties measuring emissivity, especially in the field. In some circumstances, it could show you the opposite of what you're trying to prove! I'm a Level 1 thermographer, which means basically I've learned that there are so many ways I can be tricked that I've got to be careful what conclusions I draw. Your understanding goes beyond the procedures and into the science. I'd love to hear more of your thoughts.
I'm in Tucson, in a double-wide trailer. I had to rebuild the roof and 1 south-facing wall of a corner bedroom. I did a "poor-man's" foam insulation. I bought the 1" R-Tech foam board and cut it to fit the cavities. Then, I used spray foam to seal all the way around each cavity. WAY cheaper than spray-foaming the whole thing, with essentially the same effect. I could have put a thin fiberglass over that, if I had wanted to, but it was only 10' of the south-facing wall, so it seems like it would have been kind of overkill. However, it is consistently the coolest room in the whole house, despite being in the southeast corner.
I think it would be fun to build to mock ups like two sheds or something. One with the radiant sheathing and one with regular sheathing and then test the actual physical temperature differences inside it the structures.
I put metal roof on lathes with polystyrene between the lathes. The metal roofing has venting channels that flow up to ridge vent. I put the tech shield decking on like the manufacturer suggested, it did seem backwards but I didn’t want to deviate from the engineering of it. Between the rafters, I used duro vents(some people say “egg crate”), which allow an inch an a half air gap between insulation and the radiant barrier. I brought the duro vents down to top plate of wall so that the soffit would allow cooling air to flow up between radiant barrier and insulation onward to the ridge vent. When I walked upstairs, there was a slight temperature increase when reaching the loft area, which is expected. That was before shiplap was installed on the cathedral ceiling, and before the four zone mini split was installed. I am very pleased with the results. It’s amazing, really, that everything worked so well together. You only get one chance. Now that everything is finished, the upstairs gets very cool, very quickly after the AC is turned on. One more thing, I used this method mainly to try and keep my house cool, but we live near the Texas Gulf Coast and the very high humidity can cause mold problems if you try to build an “ice chest” house. I used the latest technologies, with “old school” principles, and I have No bad issues, whatsoever. Shout out to Tom Tynan, the Home Handyman, who first turned me on to Tech Shield and the method of “vent skinning”.
For a metal roof with lathes, I wish you had used www.RoofingFoil.com Getting a radiant barrier on TOP of the roof deck is by far the best use of a radiant barrier.
I was trying to install one by myself. But, i am seeing so many contradicting views. By the way, when you said outside, did you mean silver side facing up or down?
My observation is that most people misunderstand how RBs work. 1) They are a ONE-WAY strategy. 2) They need to face out if you want to generally prevent heat from coming in (hot climates), and face in if you want to prevent heat loss (cold climates). 3) they need an air gap, at least 1” preferred, between the shiny side and whatever next structure layer (they do not work if in direct contact with something else).
Great video and very helpful for guys who are thinking of rebuilding their roof. I used LP TechShield when I rebuilt my roof a few years ago (in So Cal). It works really well, cuts summer heat a lot. I have not needed an AC since then. The down side is the house is a lot colder in winter (made the inspector hustle when he checked out the progress). So I used blow-in insulation between the joists (2x10s) and that solved the cold in winter problem.
The comparison of the west vertical wall without the radiant barrier to the roof decking with the aluminum backing is not a good comparison. The better comparison is how decking with and without the aluminum backing heats up the air under the sheathing using an dry bulb thermometer.
Using a infrared thermometer on a low emissivity surface will tell you more about the temperature of the background than the surface itself. Most of the point IR thermometers assume 0.9 surface emissivity. To be more accurate point sensor at a painted part of the surface.
But that's exactly the point. We are not trying to determine the physical temperature of the decking, but how much infrared heat the decking is emitting, which the IR thermometer is great at. I agree it will not match a contact thermometer because the emissivity of the IR thermometer is not calibrated to the ultra low emissivity of the aluminum foil.
Try sticking a piece of masking tape on the radiant barrier and the regular OSB. Aim the the thermometer at the tape to get an accurate surface temperature difference. With such a reflective surface you end up measuring the infrared it is reflecting rather than the surface temperature, not all the different than trying to measure the color of a mirrored surface. Keep the videos coming! I've learned from a bunch of them.
I understand the point you are trying to make, but an IR thermometer reads the combination of reflected and emitted radiation from a surface. The thermometer cannot differentiate between them. So when you take a temperature from a low-e surface you are getting a reading that is primarily reflection and very little information about the surface temperature itself.
I'm pretty sure if you were using a real thermal imaging camera you would see your own silhouette on the screen indicating your body temperature, not the wall temperature.
And THAT is the best way to do it. Then ventilate the attic to remove the heat. Installing it on the roof deck reflects heat back into the shingles where it drastically reduces shingle life. Heat is the enemy of shingles. Let the heat pass through the roof deck, into the attic and then ventilate it out! Seal off the conditioned interior, as you did, with the radiant barrier and insulation
Correct Mark and GaryK - Attaching radiant barrier right on the roof decking will CONDUCT heat. It loses a lot of effectiveness if the barrier itself is 150 degrees from Conduction. As GaryK said, laid on top of insulation with lots of venting if possible.
@@benjaminjoseph3392 when you mean "venting" do you mean perforated or do you mean attic venting by either ridge vents or attic fan to outside air flow?
@@ddemier Both: The barrier needs to be perforated for moisture control. Additionally, if the radiant barrier is laid horizontally on top of the insulation, then its reflecting infrared back into an attic. The attic will be hotter, ergo the attic space will need lots of ventilation so the additional heat can be carried out. My son has a physics degree and can tell you in great detail about energy transfer, I have an HVACR degree and have seen way too many attics with too little insulation and barely any outside air venting.
When measuring a reflective surface like that, you're likely to measure the reflection of your own body heat or something else in the room. Imagine that everything that's hot - including you, is actually glowing in a color that you cant see. A device like this is just measuring the light intensity of that color, so it's very prone to errors if anything's reflected.
@@damennix It's also misleading if the interior temperature is in contact with the foil. Aluminum foils (metal) are still very conductive, so if it isn't horribly warm outside, the interior temperature and the barrier's temperature will be nearly identical. The fact that he even talks about the temperature is evidence of bad conditions. Eventually, the heat from outdoors will show. Radiant barriers are, at best, a minor component to a properly insulated system. The air gap between your decking and the insulation or decking and barrier are honestly providing more value than a radiant foil. Just paper would provide almost the same benefit.
He’s actually correct. You can’t use infrared on a reflective surface and expect accurate results. I have a $12k Flir camera for work and have taken many classes on how to use it.
I'm confused... I saw another video on foil radiant barriers and they said the foil is supposed to be facing the the outside of the house towards the sun so it reflects it back..
@M Detlef Heat is still infrared. The same reason that the old incandescent light bulbs got hot. They emitted around 90% infrared light and almost no ultraviolet. Your body emits infrared, hence why you show up as white on an infrared camera.
Ernest your incorrect and so is mark. Let me try and explain it. Thermal radiation ie infrared is not what we feel from the sun. We feel UV rays.. which penetrate our skin, and COOK us from the inside. Thermal radiation is CREATED by UV radiation and can only be measured a short distance. Meaning.. that light bulb... you dont feel the heat standing 10 ft from it do you. no.. However if that thing was throwing high amounts of uv light... you would be radiating heat from the uv light it has. OBJECTS radiate heat You get sunburn from UV light not from IR light. Now that doesnt mean its not dangerous. Im not saying that.. However because UV light is the shorter light on the wavelength it holds more power. Yes the sun EMITS IR Just like a toaster but we doe not feel it. If we did... then mars and other planets closer would be HOT planets not cold. Space is -455 farenheight.. there is no way IR heat is transmitting in that temp and we are feeling it. Its all done by uv light. Uv light is Absorbed by the earth at like 90 percent which then heats up our attic ie stratosphere. what ever is not absorbed falls on the earth and bounces around and heats those objects. Then WE as a planet show IR radiation. And science THINKS it comes from the sun.. but this is a misnomer. Its done by UV light being converted INTO ir light. just like standing Next to a toaster... you can feel the heating elements... but that toaster cant make the bread toast if its outside the toaster. It has to be CLOSE for it to transfer. However.. Take the bread and put it in a solar oven when the UV index is at a 9 or 10 you will have sunburn and so will the bread... and both will be radiating IR energy from the uv hitting them.
@@N0body247 you are incorrect. Radiation travels in electromagnetic waves and does not require a medium to travel in. This is the definition of radiation. This is why there are dramatic temperature differences on the light and dark side of the moon where the atmosphere is pretty much negligible. ALL light in the EM spectrum travels through vacuumous space and if it didn't you should call NASA ESA and CSA and tell them to stop building the James Webb Telescope because it's supposed to be specifically looking at IR wavelengths radiating through space (think FLIR on steroids). This is demonstrated with a fire outside on a cold winter day and is why the surface of objects are much warmer than the air around them and is also why your friend is a jerk if he stands in between you and the fire cause you'll start feeling cold. This is also why there needs to be an airgap between the backside of the OSB and the radiant barrier. Otherwise the heat is being CONDUCTED from the OSB to the aluminum and re-radiated down. This is a similar principal used to INCREASE IR emission from aluminum plates in contact with pex tubing in hydronic systems (which is also why best installation practice is to install a reflective barrier with an air gap on the side not being heated and insulation above that.) And yes emissivity and reflectivity are problems when using IR thermometer or camera and comparing 2 different materials. The solar irradiance article on Wikipedia is a good read for information there you can see the irradiance curves and the absorption of radiation at various wavelengths from water, oxygen, and carbons dioxide... Greenhouse effect at work. You also might be interested in articles on black body radiation and emissivity.
@@N0body247 also in regards to your light bulb or toaster example, the radiant flux incident on an observer is higher the closer the observer is. This is because EM radiation (visual spectrum and heat) is being emitted in all directions from the element. The reason why you can't feel the heat is the same reason why if you take a picture of someone inches away from an incandescent light bulb they will be over exposed and 10ft away they are more likely to be properly exposed. There is more radiation incident on them. We see light in brightness and feel IR in heat. IR and all types of EM radiation is being finitely radiated out like spokes on a wheel. Further away it is the less dense it is, the less it lights or heats up an object.
When I rebuilt my roof the local building code required the radiant barrier, and I chose LP Tech Shield. I only regret not using it on the west-facing gable end as well. It works great. My insulation is in between the joists, not the rafters, so I maintained the needed air gap. Even when it is over 100 outside, the house feels like maybe 80 inside. No need for A/C now.
Love your videos. Lots of great tips and info. I’m renovating my garage with a barn dormer in the attic.I will have a 7’ ceiling at centre, but I live in a cold climate, Toronto,Canada, so I need to insulate my roof to an R50 minimum. I would really appreciate seeing how you use the radiant insulation to see if that will work for me. Thanks,Terry
5150lane I added a radiant barrier to the underside of my rafters. Massive difference in comfort and electric bills during hot Texas summers. Absolutely works and worth it.
@@AtticFoil I live south of Houston, installed AtticFoil radiant barrier last year and love it. Before I installed it, I talked to Ed, the owner of AtticFoil, and he told me to do the right things first, i.e., air sealing, mastik on the ductwork, proper ventilation, etc. Did it, installed the radiant barrier, and then had insulation blown in to R38 spec. (We also had energy efficient windows installed last year.) The combination of the results are amazing. We keep our house 4-5 degrees cooler now, and are using ~25% less energy to do so. Based on my results, if you live in an older home, I would highly recommend installing Atticfoil. You'll be happy you did.
@@budbarber4748 interesting. Would like to know a couple of things. What insulation did you have in the attic before you brought it to R-38 ? And how much ? What Windows did you have previously? How many ? Also what windows did you have put in ? Type ? Brand ? Style( double hunhs, picture Windows, etc) ? I'm in remodeling and have been for a long time. I tend to geek out on this type of info. I now this stuff helps save energy.......all of it.
The emissiivity constants for aluminum are much lower than for wood. Even if they are the same temp, the aluminum will read lower than the bare wood. There is a setting in the menue of the IR temp gun to set it appropriately forneach material.
from the shine on the barrier, looks like it will be rereflecting all the heat coming from inside back inside. not sure what the other side looks like, but really doesnt matter. It picks up heat from the other side via conduction. totally confused how this works now.
599 comments here. Radiant barrier on the roof side with airgap would be ideal then radiant barrier on rafter bottoms if an left as an unfinished space. From what you just showed you have conduction at each rafter to glued on radiant barrier to sheething. Easy fix. Blue Dow sill seal foam gasket in a roll is a closed cell foam that compress enough to provide a decent thermal break instead of all those thermal bridges. Keep up the good work and give this some thought.
I did notice that Radiant Barrier was not applied to the gable end walls. Maybe Texas has different regulations, but in California the Radiant Barrier is required to be installed on any vertical surfaces in the attic. Anyway... Thanks for the detailed explanation of how the Radiant Barrier works!!
If someone has not already pointed this out... the emissivity of shiny metal is very different than wood, which will give a different temperature indication, even if u have an emissivity adjustment on the temperature gun. A more indication would be to use a piece of masking tape on the shiny metal.
I climbed in many many attics in Texas while working there,and the coolest attic I ever entered was an older farm house that had huge louvre gable vents. That’s when I realized that we have attics because we want a pitched roof to shed water,then we almost seal up the attic because it looks better from the curb. A wide open fully vented attic is the way to go
Sorry if this question was asked already but, do you also need an air gap between the radiant barrier and the roof? Or is it only necessary between the barrier and the insulation? Dealing with a metal roof and want to make sure I install correctly! Thanks!
Hey, so I have radiant barrier but not on the OSB and I have a air gap of about 6” b/t the roof deck and the radiant barrier and it works great. I’m an inspector and almost no one puts the wider rafters and insulation to create an air gap, they just buy the radiant barrier OSB and slap it on the roof, not sure it helps at all without the proper air gap. What a waste…!
Real world example, I work on skating rink refrigeration systems. Installing a reflective ceiling absolutely reduces the refrigeration demand by over 20%. HUGE money savings in electricity for municipalities who are operating these arenas.
My entire house has radiant barriers. Other than acting like a giant faraday cage and blocking cell phone signals. It does a noticeably good job at keep the house comfortable all year long.
But, look at the bright side: When the North Koreans EMP us back to the Stone Age, your devices will still start up. They might not function without the "'Net," but they'll make nifty night lights.
At 4:30, I don't think you have thought that through.My take is: the fiberglass on the inside is a tremendously good set of air pockets - therefore the radient barrier does a great job of reflecting room heat back into it whether or not it is in contact. The foil attached to the OSB has very little air cavity with which to reflect the outside heat out and if the heat is already past the foil - too late.
You need air space around the radiant barrier so that the barrier has a place to radiate the heat to. This installation is radiating the heat inwards to that air barrier which will heat up the insulation next to it which will then radiate heat inwards to the room.
That foil has a very low emissivity of about 0.03 compared to the wood at 0.9 it is laminated to. So, it will not radiate much at all and the decking will heat up even more. It might cause heat transfer to the attic air by through convection though to a smaller degree.
@@Mattie_Ice In the video the structure is in Texas. He wants to radiate summer heat out of the structure. What he just did was install it to radiate the heat from the structure back into the structure. That could be useful for a structure located in a cold climate, which is your point. But you also need to be sure there is an air space so that the heat can be radiated at all. This guy installed this wrong.
This will not stop radiant heat from entering the building because as installed it will reflect radiant heat back into the building.@@FrankWilbanks-r8z
Would it be worth using the radiant barrier on outside walls with rigid foam that wouldn’t touch the aluminum face, and could you still get the “R” value that you would need for the walls? Nice video with a lot of info in such a short time.
I have an office over my garage and it is always hot! I would love to know more to understand how to use the various technologies to achieve the desired result of managing the heat transfer especially in challenged spaces like above garage living spaces.
Ahhh so that's why my friends shed was much cooler inside the shed on a near 100 degree day. I was just at his house and in his new shed and saying to him that his shed is much cooler inside than most sheds are. Now I know why. He has that same type of radiant barrier in his shed. I getting this put in my shed immediately.
Radiant barriers work best when there is an air gap between the radiant barrier and the outside surface. The metal attached to the wood will reflect some heat but it will also conduct the heat and radiate from the metal itself. You typically want a thin air gap and the hot air can flow out of the top ridge if you have one.
I think I understand what your saying, and I agree that a radiant barrier that doesn't touch another surface is best, but its important not to confuse emissivity with reflectivity. We are preventing the material from transferring heat via infrared light, not reflecting the infrared light away.
Jordan Smith how is it preventing radiation from entering? It is attached to the osb, and the gap is on the inside. It would prevent heat from leaving not entering.
@@curtcmiller - The sun’s energy is heating up the decking panels and the exterior roofing material. The aluminum foil overlay is preventing this built - up heat from emanating into the attic cavity and increasing the attic air temperature.
ddellwo Jordan said it would not work if it was touching the insulation. It seems like the gap is on the wrong side. To reflect it needs a gap, so it is reflecting the heat down into the house with the gap on the inside. It is attached to the osb so there is no space to reflect up.
@@curtcmiller It's working off the EMISSIVITY quality of the aluminum. Or, the ability to NOT release as much radiant heat. A simple example is if you take two hot potatoes and wrap one with foil the foil wrapped potato will stay hot longer because it is not emitting as much radiant heat. Technically TechShield does not "Reflect" any heat. It "minimizes" the amount of radiant heat being released. More info here: ua-cam.com/video/uGP5KobU6R4/v-deo.html
I just had a shed delivered today and it has this on the walls. I would like to insulate it. Will you do a video on insulating with radiant barrier? Please 🏡
That 10 degree "delta" is being held in the roof deck and shingles, it didn't vanish. It was not destroyed. Heat energy cannot be destroyed. It can be moved (as AC does), or stored (as your roof shingles are), but it does not vanish. If you doubt that, touch the glass of a heavily tinted car window in the summer sun. You say the inside of the car is cooler...and it IS...but where did the heat go? Touch the glass. Radiant barriers attached to the underside of roof decking reflect heat back into the roof deck where it is accumulated in the shingles. Heat is the enemy of shingles. Weigh the electrical savings against the reduced life of the roof. If you have a metal roof with an air space for ventilation or a tile roof with air space...great! If you have asphalt shingles it is better to install the barrier on between the attic floor and ceiling in addition to regular insulation and provide adequate ventilation, REALLY adequate ventilation, for the attic. Typical under eave vents and ridge venting and/or off ridge vents are not adequate. Powered, thermostatically controlled ventilation, properly maintained, is a better choice.
Hey Gary K, I'd like to have you're input. What if I'm building a sauna? What's the most efficient way to keep the heat INSIDE? Would I need to put a gap like he was referring to between the barrier and the inner cedar planking?
@@Revelator713 Good for you! Great trade to be in. Something to consider...the easy route when you finish school is to go into service or construction, they will be lining up to offer you jobs, and you can make good money in that. Nothing wrong with that, but it takes a huge toll on your body and by the time you are 50, hopefully you can get into a management or supervisory role...or be a building inspector or home inspector. Don't neglect your continuing education. Technology in HVAC changes so fast now, you have to keep up with it. Another route to consider is to work for a hospital or for a retail organization...like Walgreens, CVS, Walmart, etc. servicing their equipment. Or work for large property management companies on big stuff...centrifugal chillers, air handlers, etc. A lot of those places offer college tuition as a benefit. Add a degree in mechanical engineering and you have a path to high level facility management jobs, or design work for manufacturers, which pay well and are a LOT easier on your body. Four years from now you'll be about half a million $$$ ahead of people (your earnings plus their debt) who took student loans to get a liberal arts degree and end up working at Starbucks. Good luck!
@@questioneverything9539 Simple equation. Heat flows to cold. Insulation retards heat flow (doesn't stop it, it slows it down) So the best way to keep heat IN is the same thing you use to keep heat OUT...insulation. The type of insulation depends on the interior conditions of the sauna. Is it a dry sauna, or a steam room? If it is a steam room, you would want to choose an insulation that is not affected by moisture AND provide ventilation on the unconditioned side of the walls, roof. You would out the ventilation "gap" between the insulation and the exterior walls and roof. Really, no different than insulating any other space except for the moisture considerations (if any)
Great video, What is the best way in the south to keep that heat out of the attic space? In your video you are using LP Techshield radiant barrier but will you be adding any spray foam? or foam boards spaced out from the roof sheeting? is that the next step to continue from where you left off? In todays choices options for existing homes in the south ?
@@JordanSmithBuilds If you put a piece of black electrical tape, it would have given you a better point of which to measure from on the barrier. The emissivity of the surface makes a difference when taking a reading. I believe this is part of what Robert Hart was trying to convey. Also I'm interested in how this affects the life of the roof shingles. I've seen other builders speak of the need for an air gap to prevent Ice damming in the winter up here in the northeast to help prevent the type of damage to the roof which was caused by overheating the snow and melting it, then the melted snow ends up creating an "ice dam" when it cools at the bottom of the roof. You probably know about this, so I'm probably "preaching to the choir".
I put attic foil in my garage here in South Florida and it made it bearable to be in there in the summer ( along with insulating my East facing garage door. I then did the rest of the house. It's a hell of a lot of work to retrofit an attic built with 2x4s and any new construction should have this included.
Thanks Jordan. I enjoy your videos. Stupid question time. It seems shiny surfaces most effectively reflect radiant heat facing the source of that radiant heat. There are products out there to be applied to the outside of roof sheathing that are reflective generally to the same extent as the radiant barrier on common RB roof sheathing to do so. Therefore why is the shiny side of the Tech Shield, and similar products, installed having the shiny side facing the inside of the building? Certainly the other side of the foil may be shiny too but glue etc would interfere with the reflective qualities.
Willie, you are right. IDEALLY, you would put the reflective surface on TOP of the roof deck like with our Miami-Dade County approved all-in-one Underlayment AND Radiant Barrier here: www.roofingfoil.com/shop/single-sided-solid-foil-underlayment/ Unfortunately this only works for roofing systems that have a "Gap" in them. Typically metal, tile, etc. using either a batten system, or the profile has minimal contact with the roof deck. Here is my video on this: ua-cam.com/video/EyuQnvVakHs/v-deo.html
Willie, Absolutely right, the shiny foil side should be on the outside, not the inside. I built a pole barn and insulated with a foil bubble wrap (foil side looking up, not inside) and it works very well in the hot Texas sun. Bubble wrap provides the gap, and the interior is a nice bright white. Great question, not stupid at all.
My understanding was that radiant barriers need an air space between them and the source of the heat that you're trying to reflect back. The LP literature shows it installed as in this video. I'm confused.
My understanding is that it basically turns the roof deck into a hot skillet, and shortens the lifespan of the asphalt shingles, just like when someone spray-foams their attic. Having a metal roof built upon a batten system negates that, but few people are willing to spend that kind of money on their roof. I am getting ready to install a roof on a home where the customer has a finished attic space they use for their office. I am going to use a radiant barrier underlayment in an effort to make the attic/office more bearable in the summer. My customer understands the impact on the shingles but feels the trade off is worth it if it makes his office space more comfortable in the summertime.
Any tests done to see how the reflected heat then affects, the under side, of the shingles? Perhaps it heats them up even more and lessens the life span? Just curious!
@@JordanSmithBuilds it definitely helped wasn't expensive and helped us get a great hers score. Also helped keep condensation off the hvac system vs neighborhood homes drip trays constantly full.
The radiant barrier being part of the roof deck cut the effectiveness of the barrier because the side in contact with the deck has no effect. This is why I believe that it is better to install the barrier on the bottom side of the rafters. If you are putting sheet rock on the bottom side also then you put strips of thin plywood over the barrier at the rafters to create an airspace. As far as your surface temperature comparison you must remember that the temperature you measure is a function of emissivity and there is a large difference between the two surfaces. That being said, radiant barrier will transform an attic on a 90 degree day from an air temperature of 110/120 degrees to about 95 degrees. I have radiant barrier in my attic and I'm also a Test Engineer.
" the side in contact with the deck has no effect" No, I don't think so. The radiant energy is still being reflected regardless of contact, reducing the heat gain in the attic. This will likely add some heat to the wood roof deck and shingles/roofing but that heat issue is limited to the gain by conduction. This is why there's a need for additional insulation below the radiant barrier. I wonder whether planning an air gap or insulating right against the radiant barrier is actually better and suspect this may depend on many factors including choice of insulation, whether you have ridge vents, whether you're going for full encapsulation. Any time you can plan an air gap between roof deck and shingles/roofing (generally this means metal roofing) is all to the good (but this is in addition to benefits of the radiant barrier). This radiant barrier combined with metal roofing sounds great. I'd be more concerned with roofing nails penetrating deck and barrier. Cleats glued and (minimally) nailed into deck and an underlying rafter when possible would probably be best practice.
@@amerlin388 A little about my background, I have a BSME & ME and I hold a Professional Engineer's license. I specialized in thermo-fluids and heat transfer. I spent my career as a Test Engineer that being said when I said no effect this applies only to the areas of contact and since there will not be perfect contact there is a very small effect. With the barrier in contact with the deck the heat transfer is dominated by conduction while when there is an air gap radiation becomes much more important in the heat transfer. The amount of heat added to the deck and roofing is small which has been confirmed by test and measurement. The reason there is a need for insulation in addition to the radiant barrier is because the radiant barrier is only effective against radiant heat transfer. The other insulation controls conduction and convection. Of course proper design is needed to get the best results but an air gap is ALWAYS preferred over no gap. Take a trip down to your local home center and look at the insulation with reflective paper if you look at the side in contact with the fiber glass you will find that it is not reflective. Nails would not be a big deal. The radiant barrier is perferrated to allow moisture to pass through it and the area of a nail is small compared to the total area. I stand by everything I said in my original post.
@@timrothgeb416 Your original post said, "The radiant barrier being part of the roof deck cut the effectiveness of the barrier because the side in contact with the deck has NO EFFECT." The upper side of the radiant barrier, being integrated, has 100% contact with the wood roof deck, so essentially you said it has no effect. Now you refer to (small?) areas of contact with imperfect contact (meaning what?) having small effect (meaning NOT drastically impacting efficiency of radiant barrier). What was the original text trying to convey? Regarding foil-faced fiberglass insulation, it doesn't matter which side of paper has the reflective surface; the radiant energy is still reflected to the same degree. It's on the outside of the paper layer so the consumer can see at a glance that it has a foil layer. A roofer once tried to tell me shingle life is halved when installed above a radiant barrier because shingles take a hit from both sides. I could believe some effect but not anything that drastic. I would welcome your opinion. Incidentally, I wonder why this product would not have preferred installation with the foil side out (less baking of the wood in roof deck). I can only assume in practice the foil layer would be scraped/damaged by roofers during installation/shingling.
If your intending to keep heat in the space then your correct otherwise the radiant barrier needs to face the heat source with an air gap. This is how the barriers work. Also, your thermal gun will not read correct readings due to the reflectivity of the foil. That's why they are coming in lower. Tape a some paper on the barrier and you'll see more accurate readings.
When the airspace is on the "cold" side of the foil as with radiant barrier decking then the aluminum works off the EMISSIVITY quality and not the REFLECTIVITY quality. It's not quite as good, but effective. ua-cam.com/video/uGP5KobU6R4/v-deo.html You are right about using the IR gun on the foil.
@@AtticFoil I think your confused. There are three factors in radiant barriers. Absorbtivity, emmsivity, and reflectivity. They all must sum to one. Therefore, high reflectivity has low emissivity (assuming no absorbtion) Or low emissivity has high refctivity. Its really the sum that's important. It doesn't work on one property or the other....... But in order for it to work properly, it must have an air gap between it and the heat source.
STEM_SAVING So you’re telling me that if I take two hot potatoes out of the oven and wrap one with foil it won’t stay hot longer Then the one not wrapped in foil? That would be an air gap on the cold side and it would be working off of the emissivity quality.
@@AtticFoil I'm saying for your example, the foil would need to face the potato. And to work most efficient, would need an air gap. Its basic physics....emissivity + reflectivity + absorbtion =1.
Think about satellites in space. There is no cold side. The barrier is put on the outside to reflect the radiant energy (the sun) which is the heat source. So, the barrier in your example, is in backwards (unless your trying to reflect and keep heat in the attic ) and isn't operating as effectively as it should be with an air gap.
This is the info I've been looking for - thank you!! We're eventually going to install this on the roof deck behind our cape cod's knee walls and turn those areas into conditioned space. One question though: would you install baffles right to the radiant barrier, or do you think the air gap between it and the fiberglass batts that we also plan to install will be enough for air flow? Or would they be redundant since we'd have that air gap? Thanks again for your input!
All videos are talking about insulating against heat, but with winter days we want to insulate against the cold and keep the room warm, so what would be the best stuff to use on a garden shed to insulate against the cold so we can still use it in the winter, if there is any? Many thanks
Thanks for the video…if possible it would be great to see you apply the radiant barrier. ..and pointing out the air gap consistently with each application
I was snickering when you said on a previous video that on occasion, driving down the road, you see a house that they have installed it backward....shiny side out! Whoops!!! Good video-DD
So you said for it to work and not waste our money we have to have an air gap on the back side of it. What is considered an air gap or what is that? I want to see if my home builder put an air gap on the back side as you said. What do I look for?
A radiant barriers benificial characteristic in this application (physically bonded to the OSB) reduces radiant emissivity into the attic therefore reducing the temperature inside....in short and clear. But great you covered not to make contact with it.
Thank you for the video. My understanding of proper radiant barrier installation is that there should be an air pocket between the reflective barrier and the inner roof IF the attic is vented, as is the case with my attic. This allows the air entering the soffits to circulate and escape freely through the upper vents. I'm assuming the attic in this video is NOT vented (sealed) hence the direct application to the underside of the roof? I just had this done in November of 2019 and the radiant barrier was stapled to the end of the rafters creating that air pocket you mentioned in your video between the roof and the RB. I also left an opening at the upper vents and the base of the attic for air entering the soffits to circulate freely and exit the upper vents. I should note that my air handler and water heater are located in my attic. My AC failed last summer DURING a heat wave in VA, and I assumed the excessive attic heat was a contributing factor to that failure. Hopefully this will help prolong the life of my new system!
Thank you Jordan, There's always a lot to learn in your videos. I'd appreciate more on this subject of insulation and radiant, vapor and moisture barriers. Also something on configurations for various climate zones especially Pacific NW.
Hey Jordan! If your roof has an overhang, how are you supposed to finish it? Can you paint the reflective material? I don't want to see the reflective barrier from below. Thanks!
Hi, I haven’t been able to find the answer to this question anywhere... Polyiso foam board with the recycled paper/fiberglass outer coating... Is it toxic?? Using it in a van build, but it makes me nervous. Thank you.
Most insulating products for homes are meant to be covered by drywall or paneling. If you cover it with some sort of paneling or plastic, or even fabric, I would expect it to be safe. They won't likely use chemicals that will be dangerous but breathing the fiberglass dust from insulation is not good. The home improvement stores have NRP or non reinforced plastic which is used in commercial and residential bathrooms as a thin plastic wall finish which can be cleaned. It would be a good choice for a van. FRP is fiberglass reinforced plastic, which has a lot of texture and is used in commercial bathrooms. FRP is a PITA to deal with and I would not recommend it, but NRP can be cut with a utility knife. Thin wood paneling is also great to cover over insulation.
What can we use between the plywood and radiant barrier to create the air gap? The gap would be ideal because the roofing nails would damage radiant barrier if laid up against it. Thanks
FYI - all of the electromagnetic spectra transmit heat energy, from ultralow frequency radio waves to gamma rays. not just UV light. Now wavelengths which are not absorbed by the atmosphere do not directly transfer their heat to it, but do it indirectly by being absorbed by objects and the objects them retransmitting the heat energy via various means. The shorter the wavelength, the more energy per quanta, and thus the more heat energy transferred per quanta -- the sun outputs more long wave light photons than UV photons, but each UV photon has more energy on a one to one basis.
The foil touching insulation doesn't negate its reflective properties. Just cause you cover a mirror, doesn't mean it can't reflect anymore. It isn't getting visible light but still can reflect IR just as well. The reason for the gap might be that it's a vapour barrier. Vapour barriers are always to be installed on the inside, the outer layer should only block water but let vapour pass through.
Hi Jordan, I’m interested to put the radiant barriers in my attic. I’ve seen so many way to install them, which way do you recommend it. One VDO I Sal they put one big sheet cover all, is that okay?
Great video! So you mentioned you have to have air flow off the back side for the barrier to work correctly. If someone was installing rigid foam board insulation in garage panel door and then adding the radiant barrier over top/inside (the part we would see) , could that work to push out heat?
For the Foil-Backed OSB roof, if you use air gap then rockwool (or fiberglass) then dry wall it after the 2by10s, wouldn't that trap moisture which could lead to mold?
A-frame house. The section I’m thinking about currently has a sheetrock ceiling with insulation blown on top of it in the attic. Temps can get above 100F here. Can I get away with taking out the ceiling (and therefore insulation) and install this stuff as an insulation replacement and reasonably expect the space to not get super hot on a 100-degree day?
What is be the best roofing material to use with this system? What can handle the heat and how does this extra heat affect the roofing materials lifespan?
I have a question, why don't they use it on the shear on West facing and South West facing walls? I mean they use it on attics/roofs, why not on walls?
Hey Jordan,I'm going to be converting a van into a camper and I have question. Do I need a space between the van surface and the radiant barrier and a space between the barrier and the insulation or just between the barrier and th insulation? Any advice would appreciated. Thank you
I wonder: what if you add this radiant barrier, then glue a blue foam sheet into the cavity with a space in between it and the radiant barrier, then spray foam. Thoughts concerns: would it be too expensive, would the blue foam give way, do you cause new problems for the roof deck in winter (ice dams)
I have the OSB radiant barrier on my roof (Arizona) and I wanted to add the spray foam insulation. After seeing this video it made me think twice about it. My question is, can I use the 4x8 foam insulation cut into pieces that fit between the trusses while leaving space between the OSB and the actual piece of insulation to get more R value and make my house more energy efficient or will I be just waisting my money on that?
Hey Jordan, one minor point. When you use an infrared thermometer like that to measure the temperature of a low emissivity surface (aluminum foil will be about 0.03 emissivity) you need to put a small piece of masking tape on the foil surface and hold the IR thermometer very close to the tape so the only thing in its field of view is the tape. The tape emissivity will be about 0.9. This will allow you to get a much closer temperature reading of the underlying foil. Of course, remove the tape after you take the reading. Otherwise when you aim the IR thermometer at the bare foil surface the thermometer is going to "see" the reflection of the room and that is what the reading will be for. That is because a low IR emissivity equates to a high reflectivity. These IR thermometers are typically calibrated assuming the subject surface IR emissivity is about 0.9.
Good that you're thinking of the emissivity of the surfaces being compared, but I think you're missing the point.
Putting tape on the radiant barrier defeats the whole idea. Of course adding tape increases emissivity. That's exactly what the reflective product is trying to avoid - emitting heat. So the way he has done the comparison is correct. That's exactly the point he makes with the foam. If something is touching the radiant barrier, it shortcuts its magical radiant properties.
However, some radiant barrier products do have a possible downside in that if they get dirty, they increase their emissivity. They can degrade over time if they are a cheaply laminated product. Look at this same roof in 10 years or 20 years and the emissivity will have increased, for many reasons.
@@seanmaxwell4976 What he's measuring isn't useful, unfortunately. That reflective material is going to reflect both ways; from the sun->roof->radiant barrier, and from the room->radiant barrier->(and back into the room). What he is measuring is some unknown combination of the temperature of the radiant barrier * some emissivity coef + the room temperature + a reflection of his own body temperature. I don't think you can say anything with the result he gets. I bet if he positions himself closer to the barrier, he'd get a higher temperature due to the reflection. I think what he wants to measure is the effective heat flow, and there are two ways I think you could do that. The first is to get a styrofoam cooler without the lid, put a cup of cold water in it, and rest it open side against the radiant barrier / OSB. Take temperature readings every 10 minutes, the delta will give you an idea of the heat flow. You could probably get a reasonably accurate absolute measurement from this experiment.
The other way would be to go on to the roof; the temperature of the shingles above the radiant barrier should be hotter than the ones over plain OSB. This isn't as good as the first, but will give you a relative difference.
The best thing to do is just figure out what the difference in heat flow due to radiation would be. If you figure the temperature of the radiant barrier / wood is (say) 75 degrees celsius, and the ambient temperature is 50 degrees celsius, and the emissivity is 0.1 for the barrier and 0.9 for the wood, you get something like a heat transfer of 20 watts/meter for the radiant barrier and 200 watts/meter for the OSB. That's a huge difference.
@@fgbhrl4907 Great points and it's fun to think about how to measure properly. There are many difficulties measuring emissivity, especially in the field. In some circumstances, it could show you the opposite of what you're trying to prove! I'm a Level 1 thermographer, which means basically I've learned that there are so many ways I can be tricked that I've got to be careful what conclusions I draw. Your understanding goes beyond the procedures and into the science. I'd love to hear more of your thoughts.
This little section of the comments is why I like to read them. Excellent points on everyone's understanding of this system!
I'm in Tucson, in a double-wide trailer. I had to rebuild the roof and 1 south-facing wall of a corner bedroom. I did a "poor-man's" foam insulation. I bought the 1" R-Tech foam board and cut it to fit the cavities. Then, I used spray foam to seal all the way around each cavity. WAY cheaper than spray-foaming the whole thing, with essentially the same effect. I could have put a thin fiberglass over that, if I had wanted to, but it was only 10' of the south-facing wall, so it seems like it would have been kind of overkill. However, it is consistently the coolest room in the whole house, despite being in the southeast corner.
I think it would be fun to build to mock ups like two sheds or something. One with the radiant sheathing and one with regular sheathing and then test the actual physical temperature differences inside it the structures.
I put metal roof on lathes with polystyrene between the lathes. The metal roofing has venting channels that flow up to ridge vent. I put the tech shield decking on like the manufacturer suggested, it did seem backwards but I didn’t want to deviate from the engineering of it. Between the rafters, I used duro vents(some people say “egg crate”), which allow an inch an a half air gap between insulation and the radiant barrier. I brought the duro vents down to top plate of wall so that the soffit would allow cooling air to flow up between radiant barrier and insulation onward to the ridge vent. When I walked upstairs, there was a slight temperature increase when reaching the loft area, which is expected. That was before shiplap was installed on the cathedral ceiling, and before the four zone mini split was installed. I am very pleased with the results. It’s amazing, really, that everything worked so well together. You only get one chance. Now that everything is finished, the upstairs gets very cool, very quickly after the AC is turned on. One more thing, I used this method mainly to try and keep my house cool, but we live near the Texas Gulf Coast and the very high humidity can cause mold problems if you try to build an “ice chest” house. I used the latest technologies, with “old school” principles, and I have No bad issues, whatsoever. Shout out to Tom Tynan, the Home Handyman, who first turned me on to Tech Shield and the method of “vent skinning”.
For a metal roof with lathes, I wish you had used www.RoofingFoil.com Getting a radiant barrier on TOP of the roof deck is by far the best use of a radiant barrier.
Sir can you give me some information? I build my own house for my disable vet and my children
@@sansimb5735i rarely check my comments, but yes, if you get this, please do reply
In summer in Australia, the heat was unbearable at 0800, with the silver side to the outside it works so well. Very impressed.
I was trying to install one by myself. But, i am seeing so many contradicting views. By the way, when you said outside, did you mean silver side facing up or down?
My observation is that most people misunderstand how RBs work.
1) They are a ONE-WAY strategy.
2) They need to face out if you want to generally prevent heat from coming in (hot climates), and face in if you want to prevent heat loss (cold climates).
3) they need an air gap, at least 1” preferred, between the shiny side and whatever next structure layer (they do not work if in direct contact with something else).
Great video and very helpful for guys who are thinking of rebuilding their roof. I used LP TechShield when I rebuilt my roof a few years ago (in So Cal). It works really well, cuts summer heat a lot. I have not needed an AC since then. The down side is the house is a lot colder in winter (made the inspector hustle when he checked out the progress). So I used blow-in insulation between the joists (2x10s) and that solved the cold in winter problem.
The comparison of the west vertical wall without the radiant barrier to the roof decking with the aluminum backing is not a good comparison. The better comparison is how decking with and without the aluminum backing heats up the air under the sheathing using an dry bulb thermometer.
Using a infrared thermometer on a low emissivity surface will tell you more about the temperature of the background than the surface itself. Most of the point IR thermometers assume 0.9 surface emissivity. To be more accurate point sensor at a painted part of the surface.
But that's exactly the point. We are not trying to determine the physical temperature of the decking, but how much infrared heat the decking is emitting, which the IR thermometer is great at. I agree it will not match a contact thermometer because the emissivity of the IR thermometer is not calibrated to the ultra low emissivity of the aluminum foil.
Try sticking a piece of masking tape on the radiant barrier and the regular OSB. Aim the the thermometer at the tape to get an accurate surface temperature difference. With such a reflective surface you end up measuring the infrared it is reflecting rather than the surface temperature, not all the different than trying to measure the color of a mirrored surface.
Keep the videos coming! I've learned from a bunch of them.
I understand the point you are trying to make, but an IR thermometer reads the combination of reflected and emitted radiation from a surface. The thermometer cannot differentiate between them. So when you take a temperature from a low-e surface you are getting a reading that is primarily reflection and very little information about the surface temperature itself.
I'm with Robert. I'm not buying into this presentation. And I live in a cold climate so I don't see the value in this product.
I'm pretty sure if you were using a real thermal imaging camera you would see your own silhouette on the screen indicating your body temperature, not the wall temperature.
Laid mine over the ceiling / insulation in the attic . UNREAL difference .
And THAT is the best way to do it. Then ventilate the attic to remove the heat. Installing it on the roof deck reflects heat back into the shingles where it drastically reduces shingle life. Heat is the enemy of shingles. Let the heat pass through the roof deck, into the attic and then ventilate it out! Seal off the conditioned interior, as you did, with the radiant barrier and insulation
What product did you use? Is it that big of a difference? I have a 1000 sq foot home and no shade trees.
Correct Mark and GaryK - Attaching radiant barrier right on the roof decking will CONDUCT heat. It loses a lot of effectiveness if the barrier itself is 150 degrees from Conduction. As GaryK said, laid on top of insulation with lots of venting if possible.
@@benjaminjoseph3392 when you mean "venting" do you mean perforated or do you mean attic venting by either ridge vents or attic fan to outside air flow?
@@ddemier Both: The barrier needs to be perforated for moisture control. Additionally, if the radiant barrier is laid horizontally on top of the insulation, then its reflecting infrared back into an attic. The attic will be hotter, ergo the attic space will need lots of ventilation so the additional heat can be carried out. My son has a physics degree and can tell you in great detail about energy transfer, I have an HVACR degree and have seen way too many attics with too little insulation and barely any outside air venting.
When measuring a reflective surface like that, you're likely to measure the reflection of your own body heat or something else in the room. Imagine that everything that's hot - including you, is actually glowing in a color that you cant see. A device like this is just measuring the light intensity of that color, so it's very prone to errors if anything's reflected.
You are 100% right. Aluminum reflects near infrared light very well, you have to paint it or put tape on it too measure it's temperature.
@@theinvisibleman2070 Damn. Are you OK?
@@damennix It's also misleading if the interior temperature is in contact with the foil. Aluminum foils (metal) are still very conductive, so if it isn't horribly warm outside, the interior temperature and the barrier's temperature will be nearly identical. The fact that he even talks about the temperature is evidence of bad conditions. Eventually, the heat from outdoors will show.
Radiant barriers are, at best, a minor component to a properly insulated system. The air gap between your decking and the insulation or decking and barrier are honestly providing more value than a radiant foil. Just paper would provide almost the same benefit.
I don't think that type of thermometer can be trusted on any reflective surface. Stick some dark tape to your shiny surface and then measure it.
OMG wrong!
He’s actually correct. You can’t use infrared on a reflective surface and expect accurate results. I have a $12k Flir camera for work and have taken many classes on how to use it.
I'm confused...
I saw another video on foil radiant barriers and they said the foil is supposed to be facing the the outside of the house towards the sun so it reflects it back..
The heat we feel from the sun is from the infrared wavelength portion of the electromagnetic spectrum, not from the ultraviolet portion.
@M Detlef Heat is still infrared. The same reason that the old incandescent light bulbs got hot. They emitted around 90% infrared light and almost no ultraviolet. Your body emits infrared, hence why you show up as white on an infrared camera.
Ernest your incorrect and so is mark. Let me try and explain it. Thermal radiation ie infrared is not what we feel from the sun. We feel UV rays.. which penetrate our skin, and COOK us from the inside. Thermal radiation is CREATED by UV radiation and can only be measured a short distance. Meaning.. that light bulb... you dont feel the heat standing 10 ft from it do you. no.. However if that thing was throwing high amounts of uv light... you would be radiating heat from the uv light it has. OBJECTS radiate heat You get sunburn from UV light not from IR light. Now that doesnt mean its not dangerous. Im not saying that.. However because UV light is the shorter light on the wavelength it holds more power. Yes the sun EMITS IR Just like a toaster but we doe not feel it. If we did... then mars and other planets closer would be HOT planets not cold. Space is -455 farenheight.. there is no way IR heat is transmitting in that temp and we are feeling it. Its all done by uv light.
Uv light is Absorbed by the earth at like 90 percent which then heats up our attic ie stratosphere. what ever is not absorbed falls on the earth and bounces around and heats those objects. Then WE as a planet show IR radiation. And science THINKS it comes from the sun.. but this is a misnomer. Its done by UV light being converted INTO ir light.
just like standing Next to a toaster... you can feel the heating elements... but that toaster cant make the bread toast if its outside the toaster. It has to be CLOSE for it to transfer.
However.. Take the bread and put it in a solar oven when the UV index is at a 9 or 10 you will have sunburn and so will the bread... and both will be radiating IR energy from the uv hitting them.
@@N0body247 Thank you.
@@N0body247 you are incorrect. Radiation travels in electromagnetic waves and does not require a medium to travel in. This is the definition of radiation. This is why there are dramatic temperature differences on the light and dark side of the moon where the atmosphere is pretty much negligible.
ALL light in the EM spectrum travels through vacuumous space and if it didn't you should call NASA ESA and CSA and tell them to stop building the James Webb Telescope because it's supposed to be specifically looking at IR wavelengths radiating through space (think FLIR on steroids).
This is demonstrated with a fire outside on a cold winter day and is why the surface of objects are much warmer than the air around them and is also why your friend is a jerk if he stands in between you and the fire cause you'll start feeling cold.
This is also why there needs to be an airgap between the backside of the OSB and the radiant barrier. Otherwise the heat is being CONDUCTED from the OSB to the aluminum and re-radiated down. This is a similar principal used to INCREASE IR emission from aluminum plates in contact with pex tubing in hydronic systems (which is also why best installation practice is to install a reflective barrier with an air gap on the side not being heated and insulation above that.) And yes emissivity and reflectivity are problems when using IR thermometer or camera and comparing 2 different materials.
The solar irradiance article on Wikipedia is a good read for information there you can see the irradiance curves and the absorption of radiation at various wavelengths from water, oxygen, and carbons dioxide... Greenhouse effect at work. You also might be interested in articles on black body radiation and emissivity.
@@N0body247 also in regards to your light bulb or toaster example, the radiant flux incident on an observer is higher the closer the observer is. This is because EM radiation (visual spectrum and heat) is being emitted in all directions from the element. The reason why you can't feel the heat is the same reason why if you take a picture of someone inches away from an incandescent light bulb they will be over exposed and 10ft away they are more likely to be properly exposed. There is more radiation incident on them. We see light in brightness and feel IR in heat.
IR and all types of EM radiation is being finitely radiated out like spokes on a wheel. Further away it is the less dense it is, the less it lights or heats up an object.
When I rebuilt my roof the local building code required the radiant barrier, and I chose LP Tech Shield. I only regret not using it on the west-facing gable end as well. It works great. My insulation is in between the joists, not the rafters, so I maintained the needed air gap. Even when it is over 100 outside, the house feels like maybe 80 inside. No need for A/C now.
Do you can put this on roof but not on attic floor ? Would that be correct for the warmth in cold out & vise Versa?
Shouldn't the aluminum be facing up, then provide a 3/4 in. air gap, then the tile/shingles?
By all means - yes I'd like to see more about this subject. It would be great to see some strategies for retrofitting and existing home too.
Will do. Thanks!
Love your videos. Lots of great tips and info. I’m renovating my garage with a barn dormer in the attic.I will have a 7’ ceiling at centre, but I live in a cold climate, Toronto,Canada, so I need to insulate my roof to an R50 minimum. I would really appreciate seeing how you use the radiant insulation to see if that will work for me. Thanks,Terry
5150lane I added a radiant barrier to the underside of my rafters. Massive difference in comfort and electric bills during hot Texas summers. Absolutely works and worth it.
@@AtticFoil I live south of Houston, installed AtticFoil radiant barrier last year and love it. Before I installed it, I talked to Ed, the owner of AtticFoil, and he told me to do the right things first, i.e., air sealing, mastik on the ductwork, proper ventilation, etc. Did it, installed the radiant barrier, and then had insulation blown in to R38 spec. (We also had energy efficient windows installed last year.)
The combination of the results are amazing. We keep our house 4-5 degrees cooler now, and are using ~25% less energy to do so. Based on my results, if you live in an older home, I would highly recommend installing Atticfoil. You'll be happy you did.
@@budbarber4748 interesting.
Would like to know a couple of things.
What insulation did you have in the attic before you brought it to R-38 ? And how much ?
What Windows did you have previously? How many ?
Also what windows did you have put in ?
Type ? Brand ? Style( double hunhs, picture Windows, etc) ?
I'm in remodeling and have been for a long time. I tend to geek out on this type of info.
I now this stuff helps save energy.......all of it.
The emissiivity constants for aluminum are much lower than for wood. Even if they are the same temp, the aluminum will read lower than the bare wood. There is a setting in the menue of the IR temp gun to set it appropriately forneach material.
Thank you. I was screaming at the screen during the video :)
from the shine on the barrier, looks like it will be rereflecting all the heat coming from inside back inside. not sure what the other side looks like, but really doesnt matter. It picks up heat from the other side via conduction. totally confused how this works now.
599 comments here. Radiant barrier on the roof side with airgap would be ideal then radiant barrier on rafter bottoms if an left as an unfinished space. From what you just showed you have conduction at each rafter to glued on radiant barrier to sheething. Easy fix. Blue Dow sill seal foam gasket in a roll is a closed cell foam that compress enough to provide a decent thermal break instead of all those thermal bridges. Keep up the good work and give this some thought.
I'd like to know more! Especially from the perspective of dealing with high temperatures outside.
I did notice that Radiant Barrier was not applied to the gable end walls. Maybe Texas has different regulations, but in California the Radiant Barrier is required to be installed on any vertical surfaces in the attic. Anyway... Thanks for the detailed explanation of how the Radiant Barrier works!!
If someone has not already pointed this out... the emissivity of shiny metal is very different than wood, which will give a different temperature indication, even if u have an emissivity adjustment on the temperature gun. A more indication would be to use a piece of masking tape on the shiny metal.
I climbed in many many attics in Texas while working there,and the coolest attic I ever entered was an older farm house that had huge louvre gable vents. That’s when I realized that we have attics because we want a pitched roof to shed water,then we almost seal up the attic because it looks better from the curb. A wide open fully vented attic is the way to go
I'd like to see temperature readings of two roof panels side by side. One being just the OSB , and the other being the radiant barrier.
Shutyourjibbs Sure, but it does make a difference there is already enough third party engineering to prove it.
Sorry if this question was asked already but, do you also need an air gap between the radiant barrier and the roof? Or is it only necessary between the barrier and the insulation? Dealing with a metal roof and want to make sure I install correctly! Thanks!
very good description of the product. I work for Reflectix and you explained the science of radiant barriers perfectly.
Hey, so I have radiant barrier but not on the OSB and I have a air gap of about 6” b/t the roof deck and the radiant barrier and it works great.
I’m an inspector and almost no one puts the wider rafters and insulation to create an air gap, they just buy the radiant barrier OSB and slap it on the roof, not sure it helps at all without the proper air gap. What a waste…!
Do you have an air gap on the backside of that roof where you have the radiant foil on the side? Do you have your video on heat transfer?
Very informative,
I knew about this product, but I didn’t know it needed an air barrier to be effective.
Thanks Chuck
I wonder how this product compares to the fiberglass I saw on this channel #sinnisjInsulator.
Construction, science and astrophysics, nice, all subjects satisfied. I’m sold!
Great luck with your business, aloha.
Real world example, I work on skating rink refrigeration systems. Installing a reflective ceiling absolutely reduces the refrigeration demand by over 20%. HUGE money savings in electricity for municipalities who are operating these arenas.
My entire house has radiant barriers. Other than acting like a giant faraday cage and blocking cell phone signals. It does a noticeably good job at keep the house comfortable all year long.
Does it really block your cell phone signal? I was thinking about doing a radiant barrier
But, look at the bright side: When the North Koreans EMP us back to the Stone Age, your devices will still start up. They might not function without the "'Net," but they'll make nifty night lights.
^ lol
@Undefined Lastname does it really block cell phone signal?
Undefined Lastname good thing most people have WiFi calling?
If you air gap between the barrier and the insulation I assume there will be a ridge vent or is it a closed system?
There should be an air gap between the radiant barrier and the roof deck.
What is the air gap measurement. 2-3 inches?
At 4:30, I don't think you have thought that through.My take is: the fiberglass on the inside is a tremendously good set of air pockets - therefore the radient barrier does a great job of reflecting room heat back into it whether or not it is in contact. The foil attached to the OSB has very little air cavity with which to reflect the outside heat out and if the heat is already past the foil - too late.
You need air space around the radiant barrier so that the barrier has a place to radiate the heat to. This installation is radiating the heat inwards to that air barrier which will heat up the insulation next to it which will then radiate heat inwards to the room.
That foil has a very low emissivity of about 0.03 compared to the wood at 0.9 it is laminated to. So, it will not radiate much at all and the decking will heat up even more. It might cause heat transfer to the attic air by through convection though to a smaller degree.
Don't you install it according to your most dominant season?
@@Mattie_Ice In the video the structure is in Texas. He wants to radiate summer heat out of the structure. What he just did was install it to radiate the heat from the structure back into the structure. That could be useful for a structure located in a cold climate, which is your point. But you also need to be sure there is an air space so that the heat can be radiated at all. This guy installed this wrong.
It is a Radiation Barrier to reduce radiant heat transfer to the surrounding air.
This will not stop radiant heat from entering the building because as installed it will reflect radiant heat back into the building.@@FrankWilbanks-r8z
Would it be worth using the radiant barrier on outside walls with rigid foam that wouldn’t touch the aluminum face, and could you still get the “R” value that you would need for the walls? Nice video with a lot of info in such a short time.
Glad I saw you cover LP Tech shield. I'm using it with smart baffle on my cathedral ceiling.
I have an office over my garage and it is always hot! I would love to know more to understand how to use the various technologies to achieve the desired result of managing the heat transfer especially in challenged spaces like above garage living spaces.
Ahhh so that's why my friends shed was much cooler inside the shed on a near 100 degree day. I was just at his house and in his new shed and saying to him that his shed is much cooler inside than most sheds are. Now I know why. He has that same type of radiant barrier in his shed. I getting this put in my shed immediately.
Radiant barriers work best when there is an air gap between the radiant barrier and the outside surface. The metal attached to the wood will reflect some heat but it will also conduct the heat and radiate from the metal itself. You typically want a thin air gap and the hot air can flow out of the top ridge if you have one.
I think I understand what your saying, and I agree that a radiant barrier that doesn't touch another surface is best, but its important not to confuse emissivity with reflectivity. We are preventing the material from transferring heat via infrared light, not reflecting the infrared light away.
Jordan Smith how is it preventing radiation from entering? It is attached to the osb, and the gap is on the inside. It would prevent heat from leaving not entering.
@@curtcmiller - The sun’s energy is heating up the decking panels and the exterior roofing material. The aluminum foil overlay is preventing this built - up heat from emanating into the attic cavity and increasing the attic air temperature.
ddellwo Jordan said it would not work if it was touching the insulation. It seems like the gap is on the wrong side. To reflect it needs a gap, so it is reflecting the heat down into the house with the gap on the inside. It is attached to the osb so there is no space to reflect up.
@@curtcmiller It's working off the EMISSIVITY quality of the aluminum. Or, the ability to NOT release as much radiant heat. A simple example is if you take two hot potatoes and wrap one with foil the foil wrapped potato will stay hot longer because it is not emitting as much radiant heat. Technically TechShield does not "Reflect" any heat. It "minimizes" the amount of radiant heat being released. More info here: ua-cam.com/video/uGP5KobU6R4/v-deo.html
It's a bad day to be doing this but we are going to do it anyway, because on a sunny summer day it would be very hot up here and I don't like hot.
Bro , please do a video about heat tranfer , is a must for us to get ,lol
Good work Jordan
a great video will love to see more details about the heat transfer, insulation, and barriers techniques. Thanks!
I just had a shed delivered today and it has this on the walls. I would like to insulate it. Will you do a video on insulating with radiant barrier? Please 🏡
How do you get the air gap... furring strips?
That 10 degree "delta" is being held in the roof deck and shingles, it didn't vanish. It was not destroyed. Heat energy cannot be destroyed. It can be moved (as AC does), or stored (as your roof shingles are), but it does not vanish. If you doubt that, touch the glass of a heavily tinted car window in the summer sun. You say the inside of the car is cooler...and it IS...but where did the heat go? Touch the glass.
Radiant barriers attached to the underside of roof decking reflect heat back into the roof deck where it is accumulated in the shingles. Heat is the enemy of shingles. Weigh the electrical savings against the reduced life of the roof. If you have a metal roof with an air space for ventilation or a tile roof with air space...great! If you have asphalt shingles it is better to install the barrier on between the attic floor and ceiling in addition to regular insulation and provide adequate ventilation, REALLY adequate ventilation, for the attic. Typical under eave vents and ridge venting and/or off ridge vents are not adequate. Powered, thermostatically controlled ventilation, properly maintained, is a better choice.
Hey Gary K, I'd like to have you're input. What if I'm building a sauna? What's the most efficient way to keep the heat INSIDE? Would I need to put a gap like he was referring to between the barrier and the inner cedar planking?
🧠👀 makes sense, I just started hvac school
@@Revelator713 Good for you! Great trade to be in. Something to consider...the easy route when you finish school is to go into service or construction, they will be lining up to offer you jobs, and you can make good money in that. Nothing wrong with that, but it takes a huge toll on your body and by the time you are 50, hopefully you can get into a management or supervisory role...or be a building inspector or home inspector. Don't neglect your continuing education. Technology in HVAC changes so fast now, you have to keep up with it.
Another route to consider is to work for a hospital or for a retail organization...like Walgreens, CVS, Walmart, etc. servicing their equipment. Or work for large property management companies on big stuff...centrifugal chillers, air handlers, etc. A lot of those places offer college tuition as a benefit. Add a degree in mechanical engineering and you have a path to high level facility management jobs, or design work for manufacturers, which pay well and are a LOT easier on your body.
Four years from now you'll be about half a million $$$ ahead of people (your earnings plus their debt) who took student loans to get a liberal arts degree and end up working at Starbucks.
Good luck!
I wonder how this product compares to the fiberglass I saw on this channel #sinnisjInsulator.
@@questioneverything9539 Simple equation. Heat flows to cold. Insulation retards heat flow (doesn't stop it, it slows it down) So the best way to keep heat IN is the same thing you use to keep heat OUT...insulation.
The type of insulation depends on the interior conditions of the sauna. Is it a dry sauna, or a steam room? If it is a steam room, you would want to choose an insulation that is not affected by moisture AND provide ventilation on the unconditioned side of the walls, roof. You would out the ventilation "gap" between the insulation and the exterior walls and roof. Really, no different than insulating any other space except for the moisture considerations (if any)
Great video, What is the best way in the south to keep that heat out of the attic space? In your video you are using LP Techshield radiant barrier but will you be adding any spray foam? or foam boards spaced out from the roof sheeting? is that the next step to continue from where you left off? In todays choices options for existing homes in the south ?
Good job on the radiant barrier Explanation. He explained it very well and was on point with your information. Keep up the good work.
Thanks, will do!
Heat transfer video? I'm in! Cheers.
Alright! Cheers.
@@JordanSmithBuilds If you put a piece of black electrical tape, it would have given you a better point of which to measure from on the barrier. The emissivity of the surface makes a difference when taking a reading. I believe this is part of what Robert Hart was trying to convey.
Also I'm interested in how this affects the life of the roof shingles. I've seen other builders speak of the need for an air gap to prevent Ice damming in the winter up here in the northeast to help prevent the type of damage to the roof which was caused by overheating the snow and melting it, then the melted snow ends up creating an "ice dam" when it cools at the bottom of the roof. You probably know about this, so I'm probably "preaching to the choir".
I wonder how this product compares to the fiberglass I saw on this channel #sinnisjInsulator.
Please cover heat transfer in-depth. We live in the desert and thermal transfer is so important.
It's pretty simple in the desert have a minimum of a two feet thick concrete or Adobe system to store the heat then slowly release it at night
I put attic foil in my garage here in South Florida and it made it bearable to be in there in the summer ( along with insulating my East facing garage door. I then did the rest of the house. It's a hell of a lot of work to retrofit an attic built with 2x4s and any new construction should have this included.
This is good information, the heart of it being at minute 4.
They do work. Reduced the temperature in my attic by more than 30 degrees.
On which side is the air gap?
Thanks Jordan. I enjoy your videos. Stupid question time. It seems shiny surfaces most effectively reflect radiant heat facing the source of that radiant heat. There are products out there to be applied to the outside of roof sheathing that are reflective generally to the same extent as the radiant barrier on common RB roof sheathing to do so. Therefore why is the shiny side of the Tech Shield, and similar products, installed having the shiny side facing the inside of the building? Certainly the other side of the foil may be shiny too but glue etc would interfere with the reflective qualities.
Willie, you are right. IDEALLY, you would put the reflective surface on TOP of the roof deck like with our Miami-Dade County approved all-in-one Underlayment AND Radiant Barrier here: www.roofingfoil.com/shop/single-sided-solid-foil-underlayment/ Unfortunately this only works for roofing systems that have a "Gap" in them. Typically metal, tile, etc. using either a batten system, or the profile has minimal contact with the roof deck. Here is my video on this: ua-cam.com/video/EyuQnvVakHs/v-deo.html
Willie, Absolutely right, the shiny foil side should be on the outside, not the inside. I built a pole barn and insulated with a foil bubble wrap (foil side looking up, not inside) and it works very well in the hot Texas sun. Bubble wrap provides the gap, and the interior is a nice bright white. Great question, not stupid at all.
My understanding was that radiant barriers need an air space between them and the source of the heat that you're trying to reflect back. The LP literature shows it installed as in this video. I'm confused.
What about the roof shingle life expectancy? Much of reason for shingle fast decay is not having proper ventilation on the back side, right?
I'm wondering, if the radiant barrier reflects the heat back out, what effect does that have on the lifespan of the shingles?
My understanding is that it basically turns the roof deck into a hot skillet, and shortens the lifespan of the asphalt shingles, just like when someone spray-foams their attic. Having a metal roof built upon a batten system negates that, but few people are willing to spend that kind of money on their roof. I am getting ready to install a roof on a home where the customer has a finished attic space they use for their office. I am going to use a radiant barrier underlayment in an effort to make the attic/office more bearable in the summer. My customer understands the impact on the shingles but feels the trade off is worth it if it makes his office space more comfortable in the summertime.
Any tests done to see how the reflected heat then affects, the under side, of the shingles? Perhaps it heats them up even more and lessens the life span? Just curious!
I have solarhide underlayment beneath my Decra Tile roof which is on 2” batons. It makes a big difference.
Quick, simple and well explained! Thanks for this video. I'm researching if it'd going to help on my garage door in Florida. Hoping for good results
great video Jordan! I was surprised at how well this stuff works
You can really tell a difference, can't you.
@@JordanSmithBuilds it definitely helped wasn't expensive and helped us get a great hers score.
Also helped keep condensation off the hvac system vs neighborhood homes drip trays constantly full.
I wonder how this product compares to the fiberglass I saw on this channel #sinnisjInsulator.
that is very wrong. Can´t not put a vapor barrier in the exterior of insulation.
I thought it needed an air gap between it and the panel?
The radiant barrier being part of the roof deck cut the effectiveness of the barrier because the side in contact with the deck has no effect. This is why I believe that it is better to install the barrier on the bottom side of the rafters. If you are putting sheet rock on the bottom side also then you put strips of thin plywood over the barrier at the rafters to create an airspace. As far as your surface temperature comparison you must remember that the temperature you measure is a function of emissivity and there is a large difference between the two surfaces. That being said, radiant barrier will transform an attic on a 90 degree day from an air temperature of 110/120 degrees to about 95 degrees. I have radiant barrier in my attic and I'm also a Test Engineer.
" the side in contact with the deck has no effect"
No, I don't think so. The radiant energy is still being reflected regardless of contact, reducing the heat gain in the attic. This will likely add some heat to the wood roof deck and shingles/roofing but that heat issue is limited to the gain by conduction. This is why there's a need for additional insulation below the radiant barrier.
I wonder whether planning an air gap or insulating right against the radiant barrier is actually better and suspect this may depend on many factors including choice of insulation, whether you have ridge vents, whether you're going for full encapsulation.
Any time you can plan an air gap between roof deck and shingles/roofing (generally this means metal roofing) is all to the good (but this is in addition to benefits of the radiant barrier). This radiant barrier combined with metal roofing sounds great.
I'd be more concerned with roofing nails penetrating deck and barrier. Cleats glued and (minimally) nailed into deck and an underlying rafter when possible would probably be best practice.
@@amerlin388 A little about my background, I have a BSME & ME and I hold a Professional Engineer's license. I specialized in thermo-fluids and heat transfer. I spent my career as a Test Engineer that being said when I said no effect this applies only to the areas of contact and since there will not be perfect contact there is a very small effect. With the barrier in contact with the deck the heat transfer is dominated by conduction while when there is an air gap radiation becomes much more important in the heat transfer. The amount of heat added to the deck and roofing is small which has been confirmed by test and measurement. The reason there is a need for insulation in addition to the radiant barrier is because the radiant barrier is only effective against radiant heat transfer. The other insulation controls conduction and convection.
Of course proper design is needed to get the best results but an air gap is ALWAYS preferred over no gap. Take a trip down to your local home center and look at the insulation with reflective paper if you look at the side in contact with the fiber glass you will find that it is not reflective.
Nails would not be a big deal. The radiant barrier is perferrated to allow moisture to pass through it and the area of a nail is small compared to the total area.
I stand by everything I said in my original post.
@@timrothgeb416
Your original post said, "The radiant barrier being part of the roof deck cut the effectiveness of the barrier because the side in contact with the deck has NO EFFECT." The upper side of the radiant barrier, being integrated, has 100% contact with the wood roof deck, so essentially you said it has no effect. Now you refer to (small?) areas of contact with imperfect contact (meaning what?) having small effect (meaning NOT drastically impacting efficiency of radiant barrier). What was the original text trying to convey?
Regarding foil-faced fiberglass insulation, it doesn't matter which side of paper has the reflective surface; the radiant energy is still reflected to the same degree. It's on the outside of the paper layer so the consumer can see at a glance that it has a foil layer.
A roofer once tried to tell me shingle life is halved when installed above a radiant barrier because shingles take a hit from both sides. I could believe some effect but not anything that drastic. I would welcome your opinion.
Incidentally, I wonder why this product would not have preferred installation with the foil side out (less baking of the wood in roof deck). I can only assume in practice the foil layer would be scraped/damaged by roofers during installation/shingling.
This product definitely works…sold some to a customer a few years back
If your intending to keep heat in the space then your correct otherwise the radiant barrier needs to face the heat source with an air gap. This is how the barriers work. Also, your thermal gun will not read correct readings due to the reflectivity of the foil. That's why they are coming in lower. Tape a some paper on the barrier and you'll see more accurate readings.
When the airspace is on the "cold" side of the foil as with radiant barrier decking then the aluminum works off the EMISSIVITY quality and not the REFLECTIVITY quality. It's not quite as good, but effective. ua-cam.com/video/uGP5KobU6R4/v-deo.html You are right about using the IR gun on the foil.
@@AtticFoil I think your confused. There are three factors in radiant barriers. Absorbtivity, emmsivity, and reflectivity. They all must sum to one. Therefore, high reflectivity has low emissivity (assuming no absorbtion) Or low emissivity has high refctivity. Its really the sum that's important. It doesn't work on one property or the other....... But in order for it to work properly, it must have an air gap between it and the heat source.
STEM_SAVING So you’re telling me that if I take two hot potatoes out of the oven and wrap one with foil it won’t stay hot longer Then the one not wrapped in foil? That would be an air gap on the cold side and it would be working off of the emissivity quality.
@@AtticFoil I'm saying for your example, the foil would need to face the potato. And to work most efficient, would need an air gap. Its basic physics....emissivity + reflectivity + absorbtion =1.
Think about satellites in space. There is no cold side. The barrier is put on the outside to reflect the radiant energy (the sun) which is the heat source. So, the barrier in your example, is in backwards (unless your trying to reflect and keep heat in the attic ) and isn't operating as effectively as it should be with an air gap.
Does it help keep cool in winter
Very helpful. Just bought a shed and it has the heat shield on the ply. 👍🏻
This is the info I've been looking for - thank you!! We're eventually going to install this on the roof deck behind our cape cod's knee walls and turn those areas into conditioned space. One question though: would you install baffles right to the radiant barrier, or do you think the air gap between it and the fiberglass batts that we also plan to install will be enough for air flow? Or would they be redundant since we'd have that air gap? Thanks again for your input!
All videos are talking about insulating against heat, but with winter days we want to insulate against the cold and keep the room warm, so what would be the best stuff to use on a garden shed to insulate against the cold so we can still use it in the winter, if there is any? Many thanks
Thanks for the video…if possible it would be great to see you apply the radiant barrier. ..and pointing out the air gap consistently with each application
Never considered contact vs non contact of insulation.
I was snickering when you said on a previous video that on occasion, driving down the road, you see a house that they have installed it backward....shiny side out! Whoops!!! Good video-DD
shouldn't you be pointing the reflective side outwards?
No.... Odd I know, but no.
Does this radiant material apply to climates like michigan?
M Detlef fuck off asshole. He might not be a physicist okay jeez.
Yes, still works there too! For your climate area check out the SuperPerf product: atticfoil.com/index.php/products/
So could I just use wood in place of fiberglass insulation? Would it work the same?
So you said for it to work and not waste our money we have to have an air gap on the back side of it. What is considered an air gap or what is that? I want to see if my home builder put an air gap on the back side as you said. What do I look for?
A radiant barriers benificial characteristic in this application (physically bonded to the OSB) reduces radiant emissivity into the attic therefore reducing the temperature inside....in short and clear. But great you covered not to make contact with it.
Thank you for the video. My understanding of proper radiant barrier installation is that there should be an air pocket between the reflective barrier and the inner roof IF the attic is vented, as is the case with my attic. This allows the air entering the soffits to circulate and escape freely through the upper vents. I'm assuming the attic in this video is NOT vented (sealed) hence the direct application to the underside of the roof? I just had this done in November of 2019 and the radiant barrier was stapled to the end of the rafters creating that air pocket you mentioned in your video between the roof and the RB. I also left an opening at the upper vents and the base of the attic for air entering the soffits to circulate freely and exit the upper vents. I should note that my air handler and water heater are located in my attic. My AC failed last summer DURING a heat wave in VA, and I assumed the excessive attic heat was a contributing factor to that failure. Hopefully this will help prolong the life of my new system!
Did you actually watch the video? He explained his air gap and insulation.
Dave Logic yes but he didn’t explain how this heat trapped in the air gap is exhausted. Seems a ridge vented roof would be best practice.
Thank you Jordan, There's always a lot to learn in your videos. I'd appreciate more on this subject of insulation and radiant, vapor and moisture barriers. Also something on configurations for various climate zones especially Pacific NW.
isn't the alluminum supposed to be on the outside?
Is this something I could put in my floor joist in a crawl space?
Hey Jordan! If your roof has an overhang, how are you supposed to finish it? Can you paint the reflective material? I don't want to see the reflective barrier from below. Thanks!
Very informative video. Love to see more on radiant rejection info. 🦅🦅🇺🇸
Hi, I haven’t been able to find the answer to this question anywhere...
Polyiso foam board with the recycled paper/fiberglass outer coating... Is it toxic?? Using it in a van build, but it makes me nervous.
Thank you.
Most insulating products for homes are meant to be covered by drywall or paneling. If you cover it with some sort of paneling or plastic, or even fabric, I would expect it to be safe. They won't likely use chemicals that will be dangerous but breathing the fiberglass dust from insulation is not good. The home improvement stores have NRP or non reinforced plastic which is used in commercial and residential bathrooms as a thin plastic wall finish which can be cleaned. It would be a good choice for a van. FRP is fiberglass reinforced plastic, which has a lot of texture and is used in commercial bathrooms. FRP is a PITA to deal with and I would not recommend it, but NRP can be cut with a utility knife. Thin wood paneling is also great to cover over insulation.
@@CGT80 Thank you so much. We will have wood paneling over it, I was just nervous if that wasn’t enough.
What can we use between the plywood and radiant barrier to create the air gap? The gap would be ideal because the roofing nails would damage radiant barrier if laid up against it. Thanks
FYI - all of the electromagnetic spectra transmit heat energy, from ultralow frequency radio waves to gamma rays. not just UV light. Now wavelengths which are not absorbed by the atmosphere do not directly transfer their heat to it, but do it indirectly by being absorbed by objects and the objects them retransmitting the heat energy via various means. The shorter the wavelength, the more energy per quanta, and thus the more heat energy transferred per quanta -- the sun outputs more long wave light photons than UV photons, but each UV photon has more energy on a one to one basis.
Can I double up on my radiant barriers? Like one behind the other, or will I fall into the same trap as insulation behind it
The foil touching insulation doesn't negate its reflective properties. Just cause you cover a mirror, doesn't mean it can't reflect anymore. It isn't getting visible light but still can reflect IR just as well. The reason for the gap might be that it's a vapour barrier. Vapour barriers are always to be installed on the inside, the outer layer should only block water but let vapour pass through.
What are some aids to walk on so that you don't accidentally fall through the ceiling below while installing this?
Hi Jordan, I’m interested to put the radiant barriers in my attic. I’ve seen so many way to install them, which way do you recommend it. One VDO I Sal they put one big sheet cover all, is that okay?
Why not use on exterior walls that have gables and or exposed to southwestern
sun
Great video! So you mentioned you have to have air flow off the back side for the barrier to work correctly. If someone was installing rigid foam board insulation in garage panel door and then adding the radiant barrier over top/inside (the part we would see) , could that work to push out heat?
Is that the same with cold? Like if it was cold would that reflective foil and air gap keep the cold out?
Great idea, love Radiant Barrier on OSB. Would it not be prudent to use it on the South and west walls in Texas?
For the Foil-Backed OSB roof, if you use air gap then rockwool (or fiberglass) then dry wall it after the 2by10s, wouldn't that trap moisture which could lead to mold?
A-frame house. The section I’m thinking about currently has a sheetrock ceiling with insulation blown on top of it in the attic. Temps can get above 100F here. Can I get away with taking out the ceiling (and therefore insulation) and install this stuff as an insulation replacement and reasonably expect the space to not get super hot on a 100-degree day?
What is be the best roofing material to use with this system? What can handle the heat and how does this extra heat affect the roofing materials lifespan?
I live in Phoenix and I'm re-insulating the attic. Duct work is in the attic. Do you recommend radiant barrier + fiberglass insulation or foam?
I have a question, why don't they use it on the shear on West facing and South West facing walls? I mean they use it on attics/roofs, why not on walls?
Hey Jordan,I'm going to be converting a van into a camper and I have question. Do I need a space between the van surface and the radiant barrier and a space between the barrier and the insulation or just between the barrier and th insulation? Any advice would appreciated. Thank you
I wonder: what if you add this radiant barrier, then glue a blue foam sheet into the cavity with a space in between it and the radiant barrier, then spray foam.
Thoughts concerns: would it be too expensive, would the blue foam give way, do you cause new problems for the roof deck in winter (ice dams)
I have the OSB radiant barrier on my roof (Arizona) and I wanted to add the spray foam insulation. After seeing this video it made me think twice about it. My question is, can I use the 4x8 foam insulation cut into pieces that fit between the trusses while leaving space between the OSB and the actual piece of insulation to get more R value and make my house more energy efficient or will I be just waisting my money on that?