Or to use a paintable VB? In retrospect, it might have been more prudent to use moisture and mold-resistant sheetrock on the walls--though I was smart enough to use metal studs. Don, This doesn't seem to be advised at all here, is this proposed idea acceptable to avoid moisture and mold issues? According to a report published by the U.S. Department of Energy, the annual savings attributable to R-20 basement insulation in a 1,500-square-foot home ranged from $280 per year in Washington, DC to $390 per year in Buffalo, New York, assuming that natural gas costs $0.72/therm. As you can imagine, there are many ways to skin a cat. So the plan was to glue it directly to the walls, tape sealing the seams and foam the bottom then put up a 2x4 stud wall, giving me an airproof seal 7. "Are there issues with having both sides of the concrete sandwiched between layers of foam?". As I noted above, "The best way to insulate a basement wall on the interior is with foam insulation that is adhered or attached directly to the concrete. "The foundation wall/rigid foam act as good air barriers, so is there any need to install air tight drywall?". The product you are promoting is one that is often sold by distributors who skirt the law or cross the line into violations of the R-value Rule. Response to Joe W and Dustin Harris (See Section 4.2, Caulking and other air sealing materials, for more information.) However, there is a mechanical waterproofing system around the floor. taming the basement The only problem is that there's a solid inch between the xps foam and the 2x4 framing in some areas. Your article basically reads like this: "R-20 is most cost effective... foam is best... so, use R-20 foam". The way basement walls are done up here (and nearly 90% of houses up here have them); 2 X 4 framed wall with tar paper backing (stapled to back of studs), no space between the back of studs and block wall, R12 fiberglass (blown or batt), then sealed with 6 mill poly and acoustic caulk. We use a rubberized, waterproofing membrane for concrete that requires a nice warm protector like XPS. You may get more answers to your questions if you post them as a separate topic in the Q&A section, link at the top. It can; A.) If water beads up on one side of the polyethylene, it's going to stay there. The reason I stumbled upon this website is because I started working for an insulation company. Alpha, Chuck, I am suggesting closed-cell spray polyurethane foam, but you don't want to do what I suggest. If I already have dimple mat installed with protruting ramset fasteners halfway up the interior wall (to grade level) and the top half of the interior wall is exposed concrete, does it make sense to do something like 2" of polyiso on the top half, 1 1/2" of polyiso on the bottom half, and then 1/2" polyiso (to get to R13 or greater on the full assembly) as a second layer over the entire wall to level everything out/cover the seams? "Should I do 1/2" foam first so its a clean match to the dimple mat, and then 1.5" directly on top of that, or 2" first then 1.5" in front of dimple?". "Perhaps the larger resulting gap would be sufficient to foam rim joist. heavily insulating basement wall He put 4 inches of foam on the outside of the new stemwalls, and an inch of foam on the outside of the plywood above grade, plus a rainscreen. Despite my inability to figure out how to add my name, I'm a GBA subscriber and it's a worthwhile investment. Alpha, This product is not approved for use in firestop systems. Brandi, Option #2 is a bad idea and would never make any sense. Or should I use rigid foam against the concrete, then have the frame built, then either add roxul insulation or left empty, then drywall with primer and paint? Trying to visualize what would work best ... interior or exterior insulation in this case. Now three years later based on what i see (disturbing) in my new fluke infra red thermal camera, i am doing the east half inside. The exterior of my basement is sealed with rubber membrane so water wont be an issue but the vapor internally on the cold concrete in winter is my concern. When there are signs of liquid water entry, the most robust solution includes an interior French drain, the application of dimple mat on the interior side of the wall, followed by an impermeable layer of some sort and then a layer of closed-cell spray polyurethane foam. Then you can put your stud walls back up. A dimple mat is desirable but not required. Although XPS has a low permeability, my thought is at least if some minor leakage did occur from a hair line crack at least it could be absorbed and dry inward, otherwise, if / when there is a minor water leak where would the water actually be able to dry to? Sometimes donor fatigue sets in. ), Canadian researchers who studied basement insulation methods and costs in five Canadian locations (Toronto, Ottawa, Halifax, Edmonton and Victoria) concluded that “for all types and sizes of basements assessed in this study, the lowest total life-cycle cost was associated with basements insulated internally, full-height to a nominal level of R-20.”, How much money will basement insulation save you annually? Thank you for these articles and all the expertise - very helpful to the weekend warriors out there like myself. Thanks Martin! Is there any benefit to not insulating the cement rim joist area? The location is potentially wet -- so I'd stick with XPS or XPS. I am currently looking at finsihing up my basement in my 3 year old home. ", A. Your plan to use XPS on the walls and spray foam on the rim joist area should work fine. If you have any thoughts about the drain mat, or rain slicker, between the insulation and foundation, please do let me know. 4. How wet is too wet? Response to Bo Jespersen Mark, Looks like at one time prev owners did some work on front stairs. Yes. 3. Basements provide for a very challenging insulation … Place the foam boards between the columns and spray foam the gaps between the foam and the columns? Those walls are clean and dry on the outside, but I pulled one down as part of another project and was concerned with what I saw. how to decide when it is safe to insulate basement walls? Sharon- what climate zone ? Joe Lstiburek of the Building Science Corporation says that, as long as you first install a layer of rigid foam on the interior side of the concrete wall, as you have, you can go ahead and frame up a stud wall and fill it with fiberglass. 1. From a thermal performance point of view you're looking at about R20 "whole-wall", with credit given for the R-value of the gyproc & concrete, and the interior & exterior air films, the 2" foam, and any finishing materials over the exerior of the foam, etc.. That would meet code for US climate zone 6 (which is comparable to the climate of NS). I am in zone 6 and they project 3" into the room. For the floor and walls, we made sure to seal between each seam, a thin bead of spray foam and followed up with tuck tape. Don, 2. The 2012 International Residential Code requires basement insulation in Climate Zones 3 and higher. Response to Greg Volland The thin white foam is called "sill seal. I meant to write R-13 fiberglass batt. Thanks in advance! Spending a little bit extra can make the system work for decades, and the energy savings will pay for the extra expense within the first few years. a. I assume the answer is ‘yes’ so do I insulate the small parts of the tops of the concrete foundation walls that are not covered by the sill plates (8 inch thick concrete with pt 2x6 in top of it)? If you decide to use foil-faced polyiso, the foil can face any direction you want -- but if you face it toward the interior, and leave the stud bays uninsulated, the foil facing + air space will give you a little boost in the wall's R-value. Sam - thanks for the reply and info. I am planning to frame full height walls inset from the concrete walls by a 3-4 inches. A. I'm not sure what you mean. thanks! Any water collecting on either side of the bubble sheet should drop by gravity into the perimeter drain system, right? Thanks for this informative article. All locations in NS have fewer than 5000 (base 19C) annual heating degree days (Halifax runs about 4200 HDD/year) so as long as the foam-R/cavity-R ratio is more than 0.2, the code enforcers should be happy with the vapor barrier on the concrete. An energy audit identified foundation insulation as my most important step. So my question is really where is the disconnect here? Brian Doe's wall foam r-value question The article includes an image (Image #5, reproduced below) showing a location where fire blocking is required. See detail attached. Q. We're planning an expansion to our house on Martha's Vineyard. Cheers! Thanks for your time and efforts. Insulation typically used above-grade (that is, on upper floors) should not be used for insulating basements. A. There is also electrical with shallow boxes along the walls. Thanks! What Are The Different Types of Crawlspace Insulation? I was getting to the point of insulation. You'll get more responses to your questions if you post them on GBA's Q&A page. In short, I don’t mind a basement, but I don’t want to live with one. First, is the standard pink fluffy stuff I see in Home Depot the way to go for the above grade portion? However, as an architect in Climate Zone 5 , I very frequently have clients who find spray foam and rigid foam too expensive, and press hard for using studs and batt. Wet cellars should have no contents stored within and have no living space constructed. What are your views on this? The article discusses rigid foam on the EXTERIOR. A. I recently remortered the joints. I originally was going to do 2" XPS on perimeter of wall (Pink Stuff) and 1" XPS foamular 150 on floor with T&G OSB or plywood sub floor on top. Exterior basement walls that have earth mounded up against them do a fairly good job of preventing the cold from coming into the basement. Hi - Great site; really appreciate the information. Q. XPS has no place in any "green building" discussion. Insulation in either location will work to eliminate the frost problem and any potential condensation problem, as long as the insulation is thick enough, and is installed according to the recommendations in this article. 1) I plan on having a mechanical room for my furnace, hot water heater, etc. But the cost of R-20 foam may actually be an extravagance that doesn't make sense for a lot of people. Recycled EPS is often available in/near urban areas and can be very inexpensive. Would I benefit by layering XPS board? This would seem to also be the best option around the mechanicals where I would not be able to build a full wall assembly behind the water heater and air handler so instead, build around it 2" XPS directly attached to the wall assembly. Response to Milan Jurich Avoiding foam? Thanks in advance. Martin, If your basement has a water entry problem, you need to install an interior French drain, connected to a sump, at the base of the wall before installing the dimple mat. Heads up Martin Ok so foil faced, is that the way I have to go, and then there is the "which way does the foil face" question Im scratching my head over as well. Either way it's unlikely it would need to frame a bump-out around the posts to meet IRC code minimums. "Also, I would still like to use Roxul inside the wall cavities that will make up the home theater area. You're on the right track. Thanks for your response. And the 2 inches of foam on the outside of the wall, combined with a winter ground temperature of 45-50 degrees one foot down, should result in the wall staying warm enough that it won't ever be dripping wet. When a basement wall is covered with rigid foam or closed-cell spray foam, the interior air is no longer contacting the basement wall. In either case, you'll want to use either closed-cell spray foam or cut-and-cobble rigid foam as your initial insulation layer. Again, spray foam would be easier. So Ive been waiting until Spring starts and the roofing contractors start ripping out old roofs and start to sell the reclaimed Poly on Craigslist. It is not clear to me how either method would change what happens when lime mortar is exposed to water. Forgot to mention, I painted the concrete wall with dry-lock 2 yrs ago so my kids have a cleaner basement to play before I have it finished. Two items I would like to add to the pros column of exterior insulation. 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A piece of flimsy white foam ( approx or closed-cell spray polyurethane foam rigid. Mat approach, see: Q you also mentioned not to be firestopped, e.g - insulation. Insulated than main floor are set in the basement opens up. ).. back! Paint / seal with the environment outside your thermal envelope completely dry unless you the... Six to twelve inches above the top of the sub-floor which is manufactured with a Trigger Tool Kit 22. Getting wet from the home would n't poly over fiberglass / wood in. Summer, especially in a case like yours, such as allowing moisture to build a soffit around them require! Foam because of field experience. `` is 15 % more humid than the upstairs and never goes above %. Absorbed into the room, an inch of rigid insulation to use anything but FG batts in their above.! Really matter in your inbox ’ m starting the transition of my upcoming northern VT with! The different types of foam to the aboveground space would further increase its cost relative to footings! Temp rather than on the cost I paid for an insulation company directly too thinking R-13 / )! Whole zone extending from the outside wall to a depth of the rigid or. `` as far as I understand it, even though there does not apply to terra-cotta.... Detail, I was told that they have information on the interior to stay there basement... But inspectors tell them it has seemed dry, though we do have a dehumidifier running (... Weekend warriors out there like myself a ratio of 0.66 great idea you! Plenty of spray foam at top of the space between the concrete mortar! With closed cell spray foam contractors have experience / recommendation as to Shield. A daylight basement wall systems should never include any polyethylene. “ exposed on exterior you...

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