Is there anything wrong with doing that? Firstly, the manufacturers all recommend using mechanical fasteners and not just an adhesive. Been dry as a bone. I guess it depends where you live and what kind of R-value you're trying to achieve. My basement had rather large room sizes with my layout so I wasn't as concerned. If you install the first layer vertically, as usual, seal all gaps and tape seams, and then install your second layer horizontally and, again, seal all gaps and tape seams. So unfortunately my contractor and I have parted ways, and he's got my money. So, my sheets will be glued and screwed to the poured concrete foundation wall. He stated that I don’t have to insulate my cement walls since the exterior of my home already has 2” compressed foam insulation. Do these holes need to be filled before putting xps up, or is that just an unnecessary step. I plan to install laminate flooring. If I put the silver foil side to the cement wall, do you think I can use EnerBond foam adhesive ( which is recommended for Thermax), or do I have to use a foam caulk type adhesive like PL300 from Loctite? Halo® is the Advanced Graphite Insulation System that's designed perfectly for specific applications. PolyISO foam does not have to be covered, but double check with your local building code. You might even need any foam anyway... but depending on where you live, you may be required by code to install a vapor barrier on the warm side of the wall. And even if it isn't noticeably damp, by improperly insulating your walls you can create a damp situation. Additionally, one corner under the house is a near "mini basement/workroom" with almost 6 feet of headroom, about 350 sq. My basement wall has a "step in it." I am planning on using Dow Super TUFF R glued to my basement walls, with 2 x4 framing up against the TUFF R. I wanted to use THERMAX, but can't find locally. Hello, if you install rigid foam insulation to a concrete basement wall can you leave it unfinished like that or do you I live in zone 5 and the recommended R-value of insulation in a wall is R13-R15. It's going to be a lot of work, but I so don't want to use any fiber batts. If using rigid board or spray foam insulation, follow the approach as outlined for the inside of a basement (see Section 6.2, Insulating the basement from the inside). As I've covered extensively in my waterproofing section, basements are cool, damp places. How to use foam board insulation? Question is, was your drywall placed directly onto the concrete?? - Jason, I just have a simple basement that I would like to insulate. Prep Work - I've talked about basement waterproofing paint before. All we wanted was to make the walls look nice and not be so cold, and throw down a piece of outdoor carpeting. I live in Indianapolis. The house was a foreclosure and sat vacant for a few years. Hello, could I use 3/4" rigid foam board on my basement walls then build a stud wall and then put fiberglass insulation between the studs plus another vapor barrier? Good luck! Aside from any other wall treatments you want to do (I highly recommend reviewing my interior waterproofing article) the prep work basically involves making sure you have a clean dry surface. It has been a huge help. I figured the R10 XPS would do the trick for me. :o), Sherri - I agree with Jason's comments. I'm curious on the best approach for insulating over a membrane in the basement. I don't know the best answer by maybe having a professional come in and spray foam it is the best option, and I'm guessing you'll need at least R15 or so. Thanks, Is XPS a "nontoxic" product to use as replacement for sheet-rock/drywall? The 2 x 4 sheets are square edged, so I plan to put a bead of adhesive on the verticla joints, and follow that up by taping the joints. I am a single mom. Your choice really comes down to blanket insulation (aka fiberglass) or XPS. The trick there is to make sure you have the proper density to ensure adequate thermal capacity. Let's take a look. However, using a GPS rigid foam like Halo® Interra® doesn’t require attachment via cap nails, staples, etc. - Adam. Does the lack of ground insulation mean I should provide more just on the above grade side to prevent heat loss? but I'd install that (ComfortBatt) instead of fiberglass. and it has so many better qualities over fiberglass. I’m trying to skinny this because it’s a narrow stairway. The ideal Basement wall assembly to prevent mold growth: Install two inches of rigid insulation board directly against concrete. But that XPS foam in your rim joists must be, and may first also require a vapor barrier installed over the foam. Feel free to email me a picture. Thanks for your thoughts. I agree that you don't want to create what they call a "diaper" wall and trap all that moisture. As the water vapor moves through the XPS, it is slowly equilibrated with the warmer temp of the room. If your home doesn’t have it, which mine does not, then it can be a good idea for the interior wall. I live in the Northeast. - Then, cover my walls with a vapor RETARDER, not barrier. If you have a newer home, you may actually already have XPS on the outside of your foundation. Again, in colder regions, it's most definitely advisable to then put up a 2x4" wood stud wall spaced 24" OC with a pressure treated base plate. But again, I'd do research and consult with local pros. You do not need additional insulation on top of the rigid foam board on the non-exposed walls. In most basement wall situations, the foam plastic insulation material will need to be covered by a fire/ignition barrier. The rigid closed-cell foam is installed in large sheets, usually no less than one and one-half-inches thick, over the entire surface of the foundation wall. You're about to get a new friend, me! Basement Foam Board Insulation. DON'T use XPS foam panels in your situation = epic fail. Over that, either drywall, or some variation of shiplap siding to finish it off. Any advice you can offer as to how you did it? - Next step, installed 1" XPS (pink board) insulation directly over interior of block foundation using Foamboard adhesive (blue in color), taped the seams and caulked the corners. Should I hang XPS horizontally or vertically? My typically sized basement took about 35 sheets. Prior to installing the next insulation board, we add a thick bead of adhesive in the edge groove. Love the site! thank you. Would you recommend following the contour of the wall with xps, and tape all the seams, rather than leaving a gap behind the XPS and the wall on the upper half? Drywall Saw - Not 100% required but I found that with 2'' thick XPS, the box cutter did not sufficiently score the XPS to be able to snap pieces off. [NOTE from Jason: The builder for my house had pre-installed my fiberglass insulation so the choice was pretty easy for me. First we install two inches of rigid foam board insulation (closed cell). We'd like to put the rigid insulation up, but do the framing & wallboard in the warmer weather. this Stanley is under $10 and gets great reviews. I'm trying to find any products that can retard mold/mildew from growing in hidden places. Insulate the joists: Cut the strips to size Cut rigid foam insulation into strips with a table saw or a circular saw. Any help or info anyone could generate would be awesome. ), or did you do something different? Hey guys! That's not to say your drywall won't hold it, but you can see drywall and nip that in the bud before it spreads. I'm sure there are other adhesives that COULD work, but they make one specifically for applying foam board. You need to be aware of your options, and have a game plan going into your finishing project. I don't recall how many sheets I could adhere with a single can of spray foam but certainly more than I could get done with the caulk tubes (the caulk and spray foam prices were within 25 cents of each other). One wall is against a partially finished basement. Very insightful, thank you Theodore. Any help would be great appreciated! The board is more expensive than blanket insulation. Any tips on how to insulate and frame a basement over the membrane? They had a rodent problem so I had to tear all the old insulation out. - Jason, for rim joists, I recommend PolyISO foam, not XPS foam Like drywall, install full pieces covering windows and later once the adhesive is fully cured, come back and cut out your openings with the drywall saw. - Next step, installed 1" XPS (pink board) insulation directly over interior of block foundation using Foamboard adhesive (blue in color), taped the seams and caulked the corners. Now all the sheet-rock/dry wall has to be removed. Cut the XPS to fit pretty close, spray foam on back, press in place, spray foam the perimeter of the XPS, move onto the next. You can hang it either way. I'm going to put in my ceiling and internal walls to keep the house quieter. If you use the thickest (2") XPS, you will loose 2" (XPS) + 1.5" (Frame) + 0.5" (Drywall) = about 4" depending on how much you space framing off XPS. The remaining 1/4 is the laundry area, furnace and storage. One, how to hold it against the uneven wall and dampness & water being trapped behind the rigid insulation. I know some people who have laid rigid insulation directly on the concrete floor and the laminate directly on the rigid board. I don't know. mortar, cement patch, caulk, etc.) Keep in mind that XPS is a flammable material, so you’ll need to install a thermal barrier—a half-inch of gypsum board should do the trick. In the joists, personally I'd place 5.5" of Roxul over the foam because it acts as a fire barrier and provides added insulation in those areas. This will leave an air gap between the drywall and the foam. Framing will be covered with drywall. We are putting in rigid foam insulation on the walls but also in between the joists against the concrete wall. The Tuff R has foil facing on both sides, like Thermax, but one side is blue and I don't think the foil on that side is the same as Thermax. Most homes, mine included, have fiberglass batting shoved into the cavities. Again, this is good. We have an old basement and there are ridges where the wood frame was when they poured the concrete. Curious question: if you are covering foam board with a 2x4 stud wall filled with Roxul, then is a minimum 1/2" of sheet rock still required on face of stud wall or would a 3/8" sheetrock be permitted because of the use of Roxul inside the wall cavity? So, you want: concrete, XPS, fiberglass insulation or empty void, dry wall, paint. Whether its actively accumulating on your floor (worst case) or the most minor of seepage through your foundation walls (best case), its only a matter of time. Seal the foam boards together with canned foam or a high quality building tape such as Dow Weathermate Construction tape or Dupont Tyvek tape. - First off, I made sure there was no moisture problems to begin with. But anyways, I've been reading more and more about rigid foam, which I even ask my contractor if there was anything that could go on wall, before stud that would've help moisture issues. I am planning my basement remodel. The draft stopping has to bridge the space between a stud wall offset from the foundation wall, and has to run parallel to the studs... i.e. 1/2" isn't advisable, as it doesn't provide an adequate thermal break, and I highly advise against using pink (fiberglass) insulation in basements, particularly those that are damp. We would like to use XPS behind the framing. I have added a total of 4 cubic yards of dirt to the exterior next to the foundation to improve the grade away from the walls and ensured a 6' gutter run-off all the way around the house. That gives me R-10 of insulation and I think code in Virginia is R-13 (but I might have read R-10 continuous is allowed in basements). I plan to glue 1.5" XPS to the walls (I live in NJ), with panels adhering only on the areas of the stone that jut out the most. My "guess" would be to frame your walls first, then apply your insulation to the framing and leave the stone untouched. I built a 2x4 stud wall against all of the exterior walls. Good luck with your project! Point is, don't consider it to be a product to seal a wall. I would recommend going back and sealing them with some sort of hydraulic cement and toping it off with a fresh coat of waterproof paint. Unlike the fiberglass insulation, it will not hold the water needed for mold to develop and spread. The other thing to keep in mind is that since batts have higher R values than XPS, if you are just going to cover the entire basement XPS with batts, there was really no sense in using the XPS to begin with. There are two problems with this. The ground will do the insulating for you. Trying to wrap my head around it all... Jen - Sorry had a brain fart there - not 1.5'' should be 3.5" Was thinking of the 2X4 in the wrong direction. Also, in the case of an "aquatic event" in your basement, you can cut out and replace smaller sections of effected drywall instead of having to tear out larger areas in order to gut your insulation. Some have started incorporating pesticides in the foam, however. It is specifically designed not to burn the foam. Hi Ken - I afraid I can't give you any educated answers for stone walls. Constructed from top-quality materials, the product will serve you for an extended period. Ditto on the head spinning with conflicting information. Frame the 2×4 wall before the spray foam is installed, with a gap of about 2 in. Should we file those down before installation? Where this wall is below the grade of the garage floor, I THOUGHT OF USING 1/2” pink extruded rigid foam. Ted Gorab Published: Oct. 3, 2019, 6:09 p.m. Last updated: Aug. 6, 2020, 11:52 a.m. - I have poured concrete walls, with most of it below grade. I have a cinder block house and the basment is already framed. I think your instincts are correct. Interestingly, this type of insulation can fit on any part of your house, ranging from the bottom to the top. With that requirement, what's the point of using XPS? The correct method of using rigid foam is to run continuous 4-foot by 8-foot sheets of the foam across the concrete basement wall, making the rigid foam the de facto wall. I'm having a little trouble following where the styrofoam is located, but sounds like you might just be seeing where the foam was used as a concrete form. For attaching to the walls, I plan to use some adhesive, but also use plastic fasteners, probably two per sheet. I have been getting mixed results when researching, use paper backed, dont use paper back, use vapor barrier, use vapor retarder, dont use any vapor barrier or retarded with the xps foam boards. As for vapor barriers - I too researched this quite a bit and found sooooo many conflicting articles. My apologies; I just saw your private response. Been dry as a bone. 2) If using XPS foam board (which has a 'vapor barrier'), and I live near Chicago, what do you recommend between studs? I had to strap them to the roof of our Pilot. Natasha - Sorry to hear that. Thanks!!! And if your method adheres to your local building code, then you should install furring sticks between the foam and your drywall, so as to leave a small air gap between the two. What do you recommend using on the floor? cover it with the rigid foam? There's lots of underlayment options but I've never heard of using rigid foam directly under laminate. I just came across your very interesting website. 2. - Jason. And if your house is a newer construction it probably has exterior foundation insulation and other water barriers, so depending on what those are, using XPS in the interior may not be the best choice. If I fill these, what would I fill these with (i.e. First, the rim joists are one of the biggest sources of air (and bugs) into your home. I suppose adding insulation on the exposed wall can't hurt and won't be very expensive, maybe a hundred dollars or so for the batt insulation. Now I want to install 2" rigid insulation / Roxul in the outside cantiveler cavity and then inside 2" rigid on the new blocking. Should this give it enough tooth to stay put? To attach the insulation, you can use screws with large washers, a special adhesive made for adhering foam board insulation or, for smaller pieces, you can seal them in with caulk or spray foam. - I have already installed a backup sump pump with battery backup. If you want help with or more information about the issues we blog about, then let’s talk. If I put a 2” thick board of XPS up on my walls first, that gives me an R-value of 10, this means I need to put in additional insulation of R3 to R5 to achieve the recommended level. For me, in the climate I live in, the simple answer was yes. Just out of curiosity, which part of the country are you in? Thanks Adam - so just to clarify - you say you lost 1.5" for framing - can you share a bit about how you framed? We are going to finish the basement and remove all of the old insulation (we've seen some small skinks/lizards hiding in there as well as on our porch), and we want to use XPS boards along the walls before studding out and drywalling. Wrapping It Up. I have an unfinished basement. My question is: I see some are "faced" and some "unfaced". - Jason, Thanks you so much for the confirmation, I have found great things on the site already so I know I'll be visiting again!! Thanks! - Adam. Note: the pink panther guy is there, so you know it's good. Thanks! I am at a halt before I can start drywalling. If you're not concerned about losing too much headroom you could install rigid foam with OSB on top. Hi Jason, I am a Midwest (MI) resident with both egress windows and daylight windows in my unfinished basement. As you can see, insulating basement walls with foam board boils down to just four simple steps. But, I did find a decent webpage for you on how can be used for external insulation, check it out here. No solutions but we areally going through same situation. If I have to use XPS, I would have a gap due to the 2x4 top plate. If, in the end, you installed 3" of XPS or put 2" XPS and an inch of EPS, this must be covered by a thermal (fire) barrier like drywall. Frame an interior 2x4 stud wall at 24 inch centres, pressed tightly against the foam panels. I currently have the basement preframed from a previous owner. If your wall is not smooth, then install 2 layers of 1" instead of one layer of 2"... they will bend and conform to the contours of your walls easier. I assume you covered the pink board with drywall? Pretty low on time commitment too. he lower half can be the typical 6 mil poly or anything similar that is code compliant, and the upper half can be more of a smart membrane with greater permeability but it still must adhere to the same code. Do I still need a vapor barrier before drywall? - I have added about 4 cu yards of dirt around the exterior of my house to help the water flow away. It's crazy how much energy is lost for the relatively little area that's there. That adds up to a cool Gee! Read up on it on Build Science Corp's website. We have a room in our finished basement that we want to put rigid insulation onto to keep the cold out. It's a little more expensive but I have explained several times throughout this thread it's benefits over fiberglass, so read them above. Cover the insulation with a vapor barrier before you install it; all foam boards absorb water vapor. Lastly, your foam wall will need to be sealed in with a thermal (fire) barrier like drywall to meet fire code. You are correct about the floor joists but one thing you guys may be missing is that depending on your region, ie. Good luck! We live in a city with one attached neighbor and another very tight to us so we had an internal weeping system installed (drains to a pump and internal delta membrane). I would appreciate your thoughts. The basement doesn't have any water leakage. I am planning to frame in the basement and am really confused on what I should be using for insulation. The rim joist area seems to be the main area where the coldness comes through. Do you have any other suggestions? Allow me to break down the major components. Several years ago I insulated the basement walls in our basement storage room. I should add that there is some controversy about the video...specifically about nailing the tie rods further into the wall and potentially out the other side a bit. I just put a bunch of 2 inch thick XPS on my foundation walls and I ended up using about a full tube of adhesive per 4x8 board. Be sure to clean very well. Why is there a window at knee height on your basement wall? My key concern is that the walls are uneven rubble stone that is not only uneven but also not square.. That is the walls push-out and I can't imagine being able to use adhesive to hold the insulation panels in place. I know I'm a few years late to this thread but since it still comes up fairly relevant in google I thought I'd chime in here. I put 2 in XP’s on concrete walls and finerglass between the bays. Second, there is a lot of air exchange happening in that spot with the cold outside air and the warm inside air. The XPS is actually very slightly permeable to water. I would then leave the below grade basement rooms with empty stud bays. I bought your E-book which has been very helpful. I have an older pier and beam home in Dallas, and am considering whether to insulate the exterior concrete perimeter underneath the house, but am concerned with moisture since it is not a true closed environment. Is 2" still recommended? Do you frame your wall up tight against the board? When installing the foam, use caulk or tape for maximum insulation between the material and the board or floor. I'm in NJ. My plan is to finish off about 3/4 of the basement area. Cam XPS foam board be used to replace sheetrock/drywall in a below Should we just cut the nails so that the surface is flat for the XPS, or is there a better recommendation? Are we creating any hazards for fire, mold, etc.? To mitigate this, I used waterproof paint on my walls - if you haven't read my article on that, check it out! 3. Hi, Jason, Or is the rigid foam not even necessary? I argue peace of mind. The benefit is that the fiberglass won't be coming into contact with the concrete and the XPS is acting as a vapor barrier, so you avoid the inevitable mold issue with fiberglass coming into contact with the bare foundation wall. You don't want cold water vapor to meet warm air. Apply liberally - specifically in the corners and along edges of a piece. - I live in Wisconsin. Hi Wil - Thanks for coming by the website. If you get a definitive answer would you please re-comment back here so we can all know the answer? However, when it comes to rigid foam, not all are created equal, as you saw above. the basement is small. (your good one, not that fakey one you have for male enhancement pills), I hate spam, your email is safe. It will leave a gap between the board and the studs. We ensure that the boards fit together using the factory joints, and then return later to tape all seams. Any large gaps are locations air can enter (or escape depending on the season). 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