A Guide To Insulating Old Homes For HOT HUMID Climates (Part 1) | Floors, Foundations & Walls
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- Опубліковано 26 сер 2024
- Insulating an older home in a hot humid climate presents different challenges than colder or temperate climates. High levels of heat, humidity, and moisture can lead to mold growth and rot if the home is insulated improperly. Insulating eliminates dehumidification benefits provided by the air conditioning system, and over-ventilating can raise humidity levels. We will discuss common building conditions in the hot humid South, insulation strategies that work, and how to prevent and address moisture issues. This is part 1 of a 3 part series. In this video, we will be talking about floors and foundations, and common framed wall assemblies.
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Would love to see a similar video for Old Homes in Hot Dry climates. Not too many UA-cam videos on that.
I imagine you probably have a lot less to worry about...just subtract all the humid stuff and your good.....lol
This is coming from a Hot Humid homeowner..
Kidding aside, I'm sure there are some nuances you need to be aware of. It would be interesting to see what they are as I believe it would highlight and paint an entire picture for us Bot climate home owners.
@@jefftee448 I agree, I’m sure it would be much simpler. Watching these building science videos I’m so used to hearing about moisture, mold, mildew, condensation etc - meanwhile here its 4% humidity, you leave a sandwich on the counter for 2 min and the bread dries out.
Like Yuma Az.
Or cover manufacturer homes
At 9:30, what “nasty things about spray foam” are you referring to? GWP, Shrinkage, or something else?
Thanks for the videos. I'm a newly licensed builder after spending years renovating and flipping. Joe Lstiebrek, Matt Risinger, and videos like this have been a big part of me wanting to build my own simple and efficient "building science forward" houses.
Absolutely amazing videos. Love the content
Thank you so much! Stay tuned for part 2 next week.
Can you do one on converting a vented crawlspace to a sealed vs conditioned crawlspace?
Thank you for this video. I’m currently in design phase of an air-conditioned out building, in Georgia, and you confirmed my plans on using zip system, rockwool, no vapor barrier. Can’t wait to see pt 2. I will also be doing an addition to an existing home as well so it’ll come in handy there too.
Great explanation about issues with vapor going in from outside in such weather.
Excellent once again.
You mentioned benefits of thermal inertia in a topping slab - are there ways to have a workable mix that is designed to increase thermal conductivity? I know that much of the thermal mass of deeper slabs don't help to dampen diurnal temperature swings because its thermal effusivity isn't high enough - the heat can't conduct fast enough to the whole mass in time. An underfloor cooling system could make this mass "reactive" enough, and with passive house loads the temp delta can be low enough to avoid surface condensation risk.
It's part of the whole thermal mass debate which dominated passive house for so long, and is still talked about regularly in countries with mass wall construction. With a need to avoid high embodied carbon and energy materials such a concrete, it would probably be best to avoid more massive materials moving forward.
I'm sure there's some type of add mixture or recipe smarter people have discovered to increase conductivity, but I'm not aware of it. Generally we have to think about these types of things holistically, for example, providing adequate overhangs shading windows has the biggest impact on heat gain in a hot climate. If you can control that, that solves for one of the biggest problems we see with overheating. You also have to take into account the perception of the client - all they know is that the slab or tile on the slab feels cooler to them. My experience with living in a well shaded mass building is that summers are pretty nice because of that cool floor, but winters are miserable! It sucks the heat out of the house very quickly. On the opposite end of the spectrum, if there's extended periods of heat, the walls and slabs stay warmer for longer which can also be miserable.
@@ASIRIDesigns They do have some screeds designed for ufh, but I've not really looked into whether it's worth mentioning it, or if it's so minor it ends up being more of a distracting marketing term.
Totally agree with reducing loads in the first place. Solar gain etc. But there was a pretty comprehensive study (somewhere) on the effectiveness of thermal mass beyond the first 25mm from internal surfaces, because, if you want to maintain tight comfort levels, the DT and effusivity is too low to utilize the total thermal mass.
The term passive, in PH, initially included a huge emphasis on solar gain and thermal mass because they're passive effects, which has mostly gone away in recent years. Now it's more to do with reducing peak loads and glazing to fit view cones and natural light. Focus on large passive overhangs are now being replaced with active external shading. Passive cross ventilation with continuous mechanical... you get the point.
Thanks. I am newly subscribed. We are looking to buy two houses in Melbourne Australia. We can only afford older dooer uppers so this is important information that we need. I am taking the time to learn as much as possible. Long way to go though!
What vapor permeable flooring options would you recommend?
Great guide, thank you!
What are you thoughts on the "perfect wall" by Joe Lstiburek?
It would be great to compare and contrast your take on the water, air, vapor and thermal controls.
Great video, thank you. For the brick veneer retrofit, what high permeability air barrier would you consider for the interior? Would a smart membrane work or does that not reach high enough permeability?
Could you make a video for Cold Wet climate also?
Here in Norway we rarely have more than 4 weeks where it is the same or higher outside temperature than innside
Have you seen this video of mine yet? It broadly covers insulating in a cold climate: ua-cam.com/video/LMOqxyZPivQ/v-deo.htmlfeature=shared
I hope we can interest some thermal heat transfer engineers in looking at our wall assemblies. My thought is that a high specific heat material such as cement board will absorb all the radiant heat energy from the sun and, if a large enough air gap exists behind it, one that allows for good exterior airflow, the heat from the cement board can be dissipated back into the outside air and released. Assuming the temperature of the cement board is higher than the air temperature of course, but one would expect that on long hot summer days the sun facing side of the house would be significantly hotter. The insight missing in all the insulation discussions I hear is that on the sun facing side we have a strong heat transfer source, solar radiation, which is mostly infrared and ultraviolet, that travels through a vacuum until absorbed in the outer skin of the building. Having the cement board in contact with the house provided a conduction pathway. Insulation there reduces the conduction heat transfer, but it also provides a pathway for that to occur.
An open space, of the sort these new rain screen assemblies provide, allows convection heat transfer, yes, but I’m guessing that convective heat transfer is much less efficient than conductive and, if that air can escape - hopefully not into the attic, then the heat load behind it can be mitigated in that way too.
True, the cement board, the same as all other materials, when heated will emit black body radiation commensurate with its temperature, but that is emitted in both directions anyway, and I doubt that it amounts to very much heat transfer back into the building. Heat transfer from the exterior sheathing through the walls would be conductive at that point, but all your wall insulation would be in place to attenuate that. You could add a reflective surface behind the cement board, but that’s probably getting to be like a NASA project at that point. Well, my idea for you.
It would be fascinating to see some computer modeling of the radiative heat transfer to a house and then modeling to look at possible ways to mitigate it. There are more sophisticated ways of calculation insulation from heat transfer than just adding R-values. You could say that if the rain screen provides a raincoat, it also provides a parasol. Maybe my thesis is flawed in some ways, but there is something here very much worth exploring.
Reflective aluminum cladding is probably your best bet for a radiant barrier that actually works.
The term decrement delay comes to mind. The time it takes for heat on the outside to make it through to the internal surfaces. The thermal mass simply buffers the diurnal swings in temperature, smoothing them out to a milder average. But it's no substitute of insulation, which limits the heat transfer altogether.
Get loads below 25W/m2 and the mechanical systems needed for comfort are all very similar.
So, all examples shown here seem to assume that you’re tearing everything all the way down to the studs and ripping up all flooring. You could probably build a new house for less than a renovation like that.
What about smart paper barrier from the inside on the sheathing? And then some mineral wool insulation. In mixed climates? This is a brick veneer 🧱
Depends on the existing conditions, but in a mixed climate (CZ 3/4) I would probably avoid it to prevent potential mold growth on the paper.
Assuming the assembly is airtight, watertight, and R-value is the same for a CMU wall, does it matter if the insulation is in the exterior or interior in hot humid climates?
Exterior rigid foam board is preferred over a cmu wall in the humid south. You gain thermal mass on the inside of the house(where you want it) and R-value on the exterior of the house where it is continuous. You just don't see it built this way too much in the south(I live in FL) because it costs a little more than building out the interior with fiberglass bats. Just make sure you have an airgap/rainscreen with whatever exterior cladding you go with.
In south, stucco over cynder block? Any barriers?
Great question, I'm discussing those types of assemblies next week in Part 2, but you may find this other video of mine to be helpful: ua-cam.com/video/Py4k7hjJSCA/v-deo.htmlfeature=shared
Addressing your comment about spray foam, ua-cam.com/video/1TuRK3CI7jc/v-deo.htmlsi=NCrdYTap1V80W3c4&t=558, is that only in the crawlspace application or general use of closed cell spray foam?
@13:00 - I am not at all a fan of polyisocyanate insulation. The key is the string “cyan” in the name. That says to me that it’s related to cyanide, and I don’t want something in my walls that could easily turn into a poison if it catches on fire. Rockwool, yes. Fiberglass, maybe. Polyiso? No.
Buldozer. The only solution for plywood palaces.
To be fair, plywood is better than the osb spam being used on most builds nowadays