Mike, I appreciate your videos and knowledge. I’m intrigued with this attic foil on the rafters. How concerned should I be about air sealing first, and moisture accumulation behind the foil and not being able to see or treat any mold growth?
My attic is too cramped to install. Do you recommend stapling it to the decking on a complete reroof/redeck? I don't like the LP techshield because it's OSB and only 7/16 is available here.
Hi this is Aaron and I was wondering if I can use Radiant Barrier on the ceiling of my front porch it has vented soffit on it but the previous home owner took out the insulation over the porch and never put it back and I can look straight down through to my front porch from my attic....I want to put insulation back over the porch but can I just put insulation or do I need to remove the soffit and put something under it and then put it back up and then put the insulation in the attic?
Great video! To wrap my head around this, the baffle goes up against the decking and then insulation on top of that and then the foil on top of the insulation facing inward towards the living space area? Can the insulation be foam?
Dear Ninja, being in Virginia (climate zone 6-7) we have some hot humid summers and was wondering about your thoughts of painting our dark red brick home to white. (paint would be a breathable kind) Intense heat gain on the bricks continues to radiate heat back into the home after dark. I'm about 50% done with air sealing my attic and adding the radiation barrier. This is only 1/3 of solving the problem. Thanks for your videos.
Miguel - great question. Heat is transferred across an airspace or a vacuum by radiant heat. The sun's heat reaches the earth this way. Radiant heat behaves similarly to sound waves. In order for radiant heat to exist, there must be a void or an air space. In the absence of an air space, you basically have a solid. Conduction is the only way heat can move through a solid. This is done by direct contact. On a hot skillet, eggs cook like this. Radiant heat is impossible without an air space. There can be no "Radiant Barrier" without radiant heat. Due to pure aluminum's conductive nature, if you install radiant barrier foil WITHOUT the required air space, it will actually work AGAINST you and increase heat flow. Radiant barriers must have an air space on at least one side to function. We hope this answers your question. We appreciate you watching and hope you have a happy and blessed day!
First off, I don't believe in a perfect insulation design, everything has trade-offs. I think for Roof Rafter install, you would need a full soffit vent, and a full ridge vent at the top. That way you are bring in cool air from outside into every single rafter cavity and allow it to vent out the top. For my house, I think its best for a horizontal install on top of the bats of fiberglass. That way it stops eddy currents in the fiberglass, as well as the reflectivity. The dust collection might be a small issue after many, many years. The tens of thousands of little holes will allow moisture to escape.
Rather than attaching to the roof decking - 2:49 - others say air needs to be behind the foil. So attach to the rafters. With the soffit vents - make sure they are clear - and baffles - to keep them clear - and a ridge vent - the air will flow easily behind the foil.
What is the R-value of that radiant barrier I imagine it's less than 2 less than 1 alotta heat comes through that roof there is no attic ridge vent on a two story house and a lot of heat comes through the roof like I said and really heats up those rooms upstairs how would this thin basically aluminum foil keep the attic cool
Crawl Space Ninja Hey thanks for the reply I was wondering on a two-story house with an attic with no ridge vent do you think just the radiant barrier would be OK there are soffit vents on every other bay but I don't think that's enough ventilation as I said there is no ridge vent so do you think the radiant barrier stapled to the bottom of the roof decking would be sufficient to cool the house, What do you think about buying baffles but putting radiant barrier on top of the baffles that way that air space on top of the baffles can be vented down to the vents of the soffit problem is I would have to drill the soffit bird blocking since it's only drilled every other bay and I want to have every bay with holes in the bird blocking or do you think getting an attic fan would be ok, im not sure what i should do?
Shade over the house and shade inside the house are totally different. When the roof of the house absorbs the Sun there's nothing the barriers going to do from the inside to stop that
I am from central Florida and lost my huge shade tree over the garage. It’s 100 in the garage when it’s 92 outside now. Used to be the opposite. My concern for adding a barrier to my garage (the house attic is to low pitched to consider for me doing it) is the occasional wind storm or hurricane. Coming home and opening the overhead door let’s in major winds. High winds would rip it all up? Any other thoughts for Floridians.
The main thing I have been looking for in these videos, I am renting a house (in Florida) with a garage that has no ceiling. I want to apply the radiant barrier in lieu of a portable ac to keep it a little cooler while I work on my bike. Do you think moisture/condensation will be a huge factor with this product?
Thanks for the info. I have a crawlspace that has a concrete floor. Pretty deluxe. Part of my home is over the crawlspace, part over a basement that houses my boiler and geothermal equipment. There are two large 24x24" holes between the basement and crawlspace that allow air to pass freely between. Yet, in the winter the basement is much warmer than the crawlspace, making the bedroom floors above the crawlspace frigid. Would radiant barrier be wise to install?
I am only familiar with radiant barrier helping with heat from the sun. I have never installed in a crawl space to address what you are describing so I can't say if it will help. Has anyone else used radiant barrier that way? Are the crawl space foundation walls insulated? Is the subfloor in the crawl space insulated? If not, these may help hold heat from the basement longer. Hope that helps and thanks for watching.
@@CrawlSpaceNinja Thanks. The crawlspace walls are shoddily insulated with fiberglass with vinyl facing (1980s) inside the crawlspace...looks almost like a giant water heater blanket along the perimeter. I don't know if the concrete floor in the crawlspace is insulated. I assume not. My thoughts are that the radiant barrier might reflect the heat in the bedrooms from escaping through the floor into the crawlspace. In a way, that doesn't make sense because the crawlspace is cold; if the heat from the bedrooms was penetrating thru the floor then the floors wouldn't feel cold and neither would the crawlspace. ???
I know this reply is 2 years late..... I have a home that I'm remodeling currently... Walled off half the house to live in while reconstructing the other side.... Yes silicone paint helps a ton in the non conditioned space. Drops the inside temp by 10 degrees on a normal south Florida day. I'm in the process of doing radiant barrier, then rock wool on the ceiling joices. Pre drywall. And the small 11inch at the peak before finished ceiling. Will be nice and cool. You can feel the heat on the roof without the paint. And its about 140 degrees. On the painted side I walk barefoot. And only about 90 degrees.
Great info thanks for this , I was wondering if you could tell me if I could install this radiant barrier over my fiberglass isulation on my attic ceiling as I am converting the room?...
The link to a “blog post” about this doesn’t, and there appears to be no search function on the refered site, so you can’t search for it either. Pretty bait and switchy.
@@alzabo Sorry about the confusion! We've been making updates to our website so the link must have gotten broken by accident. Here is the updated link and I updated it in the description as well: diy.crawlspaceninja.com/blog/radiant-barrier-hot-attic/
I have Lp Techshield. Has anyone installed radiant barrier as well? Like have both of them. Not sure if it’s even worth the labor if it’ll be pointless to add.
Should the radiant barrier be a replacement for rockwool? Or would I see even better performance if install both radiant barrier and rockwool underneath, it in terms of not letting the house to heat up? thanks
We don't have the data on that however we have not experienced that nor heard any customers asking about issues with their phone service after we install.
Alittle confused watched a few other youtube videos that manufacture foil and they say it's best to lay over insulation in colder climates keeps heat in the insulation in the winter and out in the summer but not getting a sold answer about moisture
If installed on top of attic floor insulation, the foil will be susceptible to dust accumulation and may trap moisture in fiber insulation, so it is strongly recommended that you NOT apply radiant barriers directly on top of the attic floor insulation.
And can you use it if you have the box vents? And if it can hold moisture on the ceiling wont it hold moisture between the rafters as well? Seems to me that you would want as much air flow as possible so it seems like your attic would be alot better without it
We have a hip roof with no soffits- so no soffit vents. We have installed 2- 14" turbine vents to draw heat out. If we install the radiant barrier, how close to the roof ridge should we stop the install so the heat will go up through the turbines? And should we still leave a gap at the bottom? With a hip roof the rafters go in several directions and block where heat would travel up, unlike a normal a frame type roof, so we need some suggestions for that.
For proper air flow, with a roof-mounted radiant barrier, a gap of approximately 3 inches should be left between the radiant barrier and the insulation, and a gap of at least 6 inches should be left near the ridge. It is usually recommended that you have an air gap between 1/2 inch and 3/4 inch for the radiant barrier to function properly. It is also possible to create air gaps larger than this one - they promote ventilation on the foil, keep the air dry, and help keep the air temperature lower. Due to the fact that insulation is technically a solid with a lot of air inside, it is not an air gap.
The radiant barrier would still need to be installed to not touch the roof deck and you would need to have some type of active/passive vents, but I see no reason why saying flat roofs would not benefit when installed correctly.
We have seen the bubble wrap type insulation installed and think it looks great. Is that what you are referring to or radiant barrier alone? Radiant barrier does need an air pocket to work effectively according to the manufacturers we have seen.
We do not recommend laying it on the ground, nor does the Department of Energy. Check out this article for more info: www.energy.gov/energysaver/weatherize/insulation/radiant-barriers
Having a cooler attic doesn’t matter. The difference a radiant barrier might make is not going to make a difference on interior cooling & comfort if sufficient insulation exists. There is a reason radiant barrier pushers don’t offer any sort of savings, reduction in kWh usage, or change in interior comfort guarantees.
Huge difference. You've never tried it? Having a cooler attic does matter. Is your house insulated in a vacuum or something? Insulation gets hot and transfers heat to the house, while attempting to slow the transfer.
We offer radiant barrier and other hot attic solutions on our DIY Store: goo.gl/o7mtpH
Crawl Space Ninja do you guys use butyl tape to seal the barrier to the walls or what do you use?
This is the first time I've heard not to lay radiant barrier on top of insulation. I see your point though.
I approve of this message.
Great thanks
You are welcome
Mike, I appreciate your videos and knowledge. I’m intrigued with this attic foil on the rafters. How concerned should I be about air sealing first, and moisture accumulation behind the foil and not being able to see or treat any mold growth?
I did will see if it really works
please keep us posted
Honest.
Thank you!
My attic is too cramped to install. Do you recommend stapling it to the decking on a complete reroof/redeck? I don't like the LP techshield because it's OSB and only 7/16 is available here.
Hi this is Aaron and I was wondering if I can use Radiant Barrier on the ceiling of my front porch it has vented soffit on it but the previous home owner took out the insulation over the porch and never put it back and I can look straight down through to my front porch from my attic....I want to put insulation back over the porch but can I just put insulation or do I need to remove the soffit and put something under it and then put it back up and then put the insulation in the attic?
Great video! To wrap my head around this, the baffle goes up against the decking and then insulation on top of that and then the foil on top of the insulation facing inward towards the living space area? Can the insulation be foam?
Dear Ninja, being in Virginia (climate zone 6-7) we have some hot humid summers and was wondering about your thoughts of painting our dark red brick home to white. (paint would be a breathable kind)
Intense heat gain on the bricks continues to radiate heat back into the home after dark.
I'm about 50% done with air sealing my attic and adding the radiation barrier. This is only 1/3 of solving the problem.
Thanks for your videos.
Did you get an answer? I'm in the same situation with my brick home.
@@goff2311????
Isn’t it recommended to leave an air gap and install onto the rafters to not cause conduction?
Miguel - great question. Heat is transferred across an airspace or a vacuum by radiant heat. The sun's heat reaches the earth this way. Radiant heat behaves similarly to sound waves. In order for radiant heat to exist, there must be a void or an air space. In the absence of an air space, you basically have a solid. Conduction is the only way heat can move through a solid. This is done by direct contact. On a hot skillet, eggs cook like this. Radiant heat is impossible without an air space. There can be no "Radiant Barrier" without radiant heat. Due to pure aluminum's conductive nature, if you install radiant barrier foil WITHOUT the required air space, it will actually work AGAINST you and increase heat flow. Radiant barriers must have an air space on at least one side to function. We hope this answers your question. We appreciate you watching and hope you have a happy and blessed day!
First off, I don't believe in a perfect insulation design, everything has trade-offs. I think for Roof Rafter install, you would need a full soffit vent, and a full ridge vent at the top. That way you are bring in cool air from outside into every single rafter cavity and allow it to vent out the top. For my house, I think its best for a horizontal install on top of the bats of fiberglass. That way it stops eddy currents in the fiberglass, as well as the reflectivity. The dust collection might be a small issue after many, many years. The tens of thousands of little holes will allow moisture to escape.
Thanks for your insight! Every home is different so different solutions are needed.
Rather than attaching to the roof decking - 2:49 - others say air needs to be behind the foil. So attach to the rafters. With the soffit vents - make sure they are clear - and baffles - to keep them clear - and a ridge vent - the air will flow easily behind the foil.
What is the R-value of that radiant barrier I imagine it's less than 2 less than 1 alotta heat comes through that roof there is no attic ridge vent on a two story house and a lot of heat comes through the roof like I said and really heats up those rooms upstairs how would this thin basically aluminum foil keep the attic cool
here is a video of radient barrier ua-cam.com/video/6vVfdM4yzMs/v-deo.html hopefully that helps answer your question.
Crawl Space Ninja Hey thanks for the reply I was wondering on a two-story house with an attic with no ridge vent do you think just the radiant barrier would be OK there are soffit vents on every other bay but I don't think that's enough ventilation as I said there is no ridge vent so do you think the radiant barrier stapled to the bottom of the roof decking would be sufficient to cool the house, What do you think about buying baffles but putting radiant barrier on top of the baffles that way that air space on top of the baffles can be vented down to the vents of the soffit problem is I would have to drill the soffit bird blocking since it's only drilled every other bay and I want to have every bay with holes in the bird blocking or do you think getting an attic fan would be ok, im not sure what i should do?
Can i put this on my ice Box
Shade over the house and shade inside the house are totally different. When the roof of the house absorbs the Sun there's nothing the barriers going to do from the inside to stop that
Can this work in a crawl space with keeping heat in a home in winter?
I am from central Florida and lost my huge shade tree over the garage. It’s 100 in the garage when it’s 92 outside now. Used to be the opposite. My concern for adding a barrier to my garage (the house attic is to low pitched to consider for me doing it) is the occasional wind storm or hurricane. Coming home and opening the overhead door let’s in major winds. High winds would rip it all up? Any other thoughts for Floridians.
They do make a paintable radiant barrier but I have never used it. Hope that helps and thanks for watching. amzn.to/3rrVbGr
The main thing I have been looking for in these videos, I am renting a house (in Florida) with a garage that has no ceiling. I want to apply the radiant barrier in lieu of a portable ac to keep it a little cooler while I work on my bike. Do you think moisture/condensation will be a huge factor with this product?
It could be in a humid environment like FL, may want to do a test area to see how it performs.
Thanks for the info. I have a crawlspace that has a concrete floor. Pretty deluxe. Part of my home is over the crawlspace, part over a basement that houses my boiler and geothermal equipment. There are two large 24x24" holes between the basement and crawlspace that allow air to pass freely between. Yet, in the winter the basement is much warmer than the crawlspace, making the bedroom floors above the crawlspace frigid. Would radiant barrier be wise to install?
I am only familiar with radiant barrier helping with heat from the sun. I have never installed in a crawl space to address what you are describing so I can't say if it will help. Has anyone else used radiant barrier that way? Are the crawl space foundation walls insulated? Is the subfloor in the crawl space insulated? If not, these may help hold heat from the basement longer. Hope that helps and thanks for watching.
@@CrawlSpaceNinja Thanks. The crawlspace walls are shoddily insulated with fiberglass with vinyl facing (1980s) inside the crawlspace...looks almost like a giant water heater blanket along the perimeter. I don't know if the concrete floor in the crawlspace is insulated. I assume not. My thoughts are that the radiant barrier might reflect the heat in the bedrooms from escaping through the floor into the crawlspace. In a way, that doesn't make sense because the crawlspace is cold; if the heat from the bedrooms was penetrating thru the floor then the floors wouldn't feel cold and neither would the crawlspace. ???
would painting the roof with that white reflective paint cause any issues with the radiant barrier?
That is not a procedure that we tend to follow.
I know this reply is 2 years late.....
I have a home that I'm remodeling currently... Walled off half the house to live in while reconstructing the other side....
Yes silicone paint helps a ton in the non conditioned space. Drops the inside temp by 10 degrees on a normal south Florida day. I'm in the process of doing radiant barrier, then rock wool on the ceiling joices.
Pre drywall. And the small 11inch at the peak before finished ceiling. Will be nice and cool. You can feel the heat on the roof without the paint. And its about 140 degrees. On the painted side I walk barefoot. And only about 90 degrees.
Michael- I have read lawsuit in Texas that it claims that this stuff increased lightning strikes and caused fires. Any thoughts?
Really, I have not seen that but will look into it - thanks for heads up.
Great info thanks for this , I was wondering if you could tell me if I could install this radiant barrier over my fiberglass isulation on my attic ceiling as I am converting the room?...
Radiant barrier should be installed on the roof decking with an air gap between the radiant barrier and the decking.
@@CrawlSpaceNinja Huh? I believe you mean the trusses/rafters.
The link to a “blog post” about this doesn’t, and there appears to be no search function on the refered site, so you can’t search for it either.
Pretty bait and switchy.
@@alzabo Sorry about the confusion! We've been making updates to our website so the link must have gotten broken by accident. Here is the updated link and I updated it in the description as well: diy.crawlspaceninja.com/blog/radiant-barrier-hot-attic/
I have Lp Techshield. Has anyone installed radiant barrier as well? Like have both of them. Not sure if it’s even worth the labor if it’ll be pointless to add.
For questions like that feel free to submit a Ask a Ninja Form - crawlspaceninja.com/ask-a-ninja/
Should the radiant barrier be a replacement for rockwool? Or would I see even better performance if install both radiant barrier and rockwool underneath, it in terms of not letting the house to heat up? thanks
Does it mess up your cell phones signal?
We don't have the data on that however we have not experienced that nor heard any customers asking about issues with their phone service after we install.
Alittle confused watched a few other youtube videos that manufacture foil and they say it's best to lay over insulation in colder climates keeps heat in the insulation in the winter and out in the summer but not getting a sold answer about moisture
If installed on top of attic floor insulation, the foil will be susceptible to dust accumulation and may trap moisture in fiber insulation, so it is strongly recommended that you NOT apply radiant barriers directly on top of the attic floor insulation.
Does air still get thro that just as good without it?
And can you use it if you have the box vents? And if it can hold moisture on the ceiling wont it hold moisture between the rafters as well? Seems to me that you would want as much air flow as possible so it seems like your attic would be alot better without it
You guys do New Jersey?
Not as of 1/25/21 but we hope to be soon.
how would you recommend removing radiant barrier from attic floor that the previous owner put down?
Before you remove the radiant berries where you live? You might not need to.
We have a hip roof with no soffits- so no soffit vents. We have installed 2- 14" turbine vents to draw heat out. If we install the radiant barrier, how close to the roof ridge should we stop the install so the heat will go up through the turbines? And should we still leave a gap at the bottom? With a hip roof the rafters go in several directions and block where heat would travel up, unlike a normal a frame type roof, so we need some suggestions for that.
For proper air flow, with a roof-mounted radiant barrier, a gap of approximately 3 inches should be left between the radiant barrier and the insulation, and a gap of at least 6 inches should be left near the ridge. It is usually recommended that you have an air gap between 1/2 inch and 3/4 inch for the radiant barrier to function properly. It is also possible to create air gaps larger than this one - they promote ventilation on the foil, keep the air dry, and help keep the air temperature lower. Due to the fact that insulation is technically a solid with a lot of air inside, it is not an air gap.
How effective are radiant barriers for flat roof attics?
The radiant barrier would still need to be installed to not touch the roof deck and you would need to have some type of active/passive vents, but I see no reason why saying flat roofs would not benefit when installed correctly.
Would you recommend putting foil over duct work also?
We have seen the bubble wrap type insulation installed and think it looks great. Is that what you are referring to or radiant barrier alone? Radiant barrier does need an air pocket to work effectively according to the manufacturers we have seen.
@@CrawlSpaceNinja yes - the bubble wrap type insulation. Is this something you offer? Thanks!
Will galvanised sheets do the same thing?
I imagine they would rust like crazy in the moisture, plus galvanized doesn't "breathe".
If the foil has larger perforated holes is it ok to lay it on the ground? It is advertised for northern states
We do not recommend laying it on the ground, nor does the Department of Energy. Check out this article for more info: www.energy.gov/energysaver/weatherize/insulation/radiant-barriers
Does the barrier come in 24" width?
Ed, yes it does.
Why is it double sided?
They aren't all double sided, I think some of them just are so it can be installed either way.
Wooo, same name, same voice, no beard!
Matthew McConaughey explains radiant barriers...
Just a warning, you'll lose cell phone coverage after install.
Could it act like a ‘faraday cage’?
Having a cooler attic doesn’t matter. The difference a radiant barrier might make is not going to make a difference on interior cooling & comfort if sufficient insulation exists. There is a reason radiant barrier pushers don’t offer any sort of savings, reduction in kWh usage, or change in interior comfort guarantees.
Thanks for sharing
Huge difference. You've never tried it? Having a cooler attic does matter. Is your house insulated in a vacuum or something? Insulation gets hot and transfers heat to the house, while attempting to slow the transfer.