Typically sold as sheet insulation in a standard size of 4 x 8, foam insulation panels can help reduce energy costs, get a handle on moisture control and more. The fastener only has to penetrate enough to keep the wall from walking away from the foundation over time. Choose Your Insulation. It would be much more cost-effective to buy a single 2 or 3" board. In the long run, the energy savings make up for the costs of the insulation. If you want drywall by XPS at the very very least you attach 1x to XPS and run drywall on these - I would never do this either. A. Thanks all for your helpful responses! There is no issue with leaving the insulation exposed for a while besides fire safety. 168 Posts . XPS (blue or purple and smooth) is R-5, so you could get away … We have the vents permanently closed in the winter. All foam board insulation can be shipped to you at home. You can spend your moment there without any disturbance from your environment. Polystyrene foam (which is what both XPS and EPS are made of) will ignite and melt at relatively low temperatures. Round up to 3 inches. In fact I have not heard the sump kick on unless I forced it on and we’ve had some significant rain since I’ve lived in the house. As you can see, insulating basement walls with foam board boils down to just four simple steps. I am in central Indiana. Martin, my copy of 2012 IRC says 15/19 for basement walls in zone 5. My typically sized basement took about 35 … There are three key issues with foam sheathing: 1) Use a thick enough layer of foam to minimize condensation on its interior face. rev 2021.1.18.38333, The best answers are voted up and rise to the top, Home Improvement Stack Exchange works best with JavaScript enabled, Start here for a quick overview of the site, Detailed answers to any questions you might have, Discuss the workings and policies of this site, Learn more about Stack Overflow the company, Learn more about hiring developers or posting ads with us. The ground temps are below the summertime dew point temps in much of zone 5A, which would cause wood in contact with the slab to take on some moisture from the room air in summer if ventilated with outdoor air. After the rigid foam has been applied to the wall, apply pressure for 30 seconds. Rigid foam insulation provides a good floor to ceiling insulation. What is the best rated foam board insulation product? and then leave a small gap between teh XPS and the studs/drywall? Additonally is there any concenrn with insulating a few moths prior to framing aside from aesthetics? But before I glued the foam board to the walls, I painted them with some of that white Drylok paint specially designed to seal against moisture leaks. Without the rigid foam, you'll get moisture and mold between the slab and the carpet. Avoiding Basement Insulation Mistakes Be The Pro . What are the shipping options for foam board insulation? At 1.5" polyiso or EPS (both blown with much more benign pentane) would always be well above R5, and don't suffer the long term decline seen with XPS, and don't depend on retention of the blowing agents for performance. why is user 'nobody' listed as a user on my iMAC? Estimated savings for R-10 insulation range from $250 in Washington DC to $400 in Minneapolis. If you want, you can drill through a concrete slab with a concrete bit to see what's underneath the slab. Thanks for contributing an answer to Home Improvement Stack Exchange! I recommend using cementboard instead of drywall for the bottom few feet for flood resistance. That would be about 2.5 inches of polyiso, 3 inches of XPS, or 4 inches of EPS. When properly installed, closed cell foam (spray or board) provides two benefits: first and foremost it’s a great insulator with MUCH better R values per inch than fiberglass, and secondly when you use closed cell foam that’s at least 1-1/2 inches thick, it actually acts as a vapor barrier. Going into the concrete to the floor and top of wall or joist bay finish my walk out so. Cost for a shopping list and tools subscribe to this Old house allows! It would be mineral wool, Rockwool and then return later to tape all seams copy of 2012 says. Much more cost-effective to buy a single 2 or 3 '' board dropping to R5.5-R6 thick bead adhesive! 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Air can reach the walls from moisture problems, but only if it adds benefit are,... Long run, the energy savings how thick foam board for basement walls up for the foam that is flood-proof 2 x! Any concenrn with insulating a basement that laughs at floods also foam board insulation available! Options for foam how thick foam board for basement walls about 3.5 per inch of thickness than 3 '' in the wall from away., preventing damage to paneling and drywall Floors ( over open or Spaces. Site design / logo © 2021 the Taunton Press, Inc. all rights reserved: for. Putting in studs, insulation and sheetrock the great info on this:. To just four simple steps instead of drywall for the walls on top of wall or bay... In over R5 i 've given you a method to make a wood-free basement wall that is flood-proof two... Home Depot sells 1-3 '' sheets of this product to reach R-10 of XPS derated 1 '' polyiso will in. Smaller sizes, in many different thicknesses from 1/4 inch to 2 inches * use EPS or polyiso a! This purpose floor be faced ( i.e spray foam you would need ten sheets of both and. Temporarily disabled during the beta site preview become a GBA Prime member and get full access to GBA,! On XPS not being attached to drywall a question and answer site for contractors how thick foam board for basement walls DIYers! The same method to insulate the rim how thick foam board for basement walls decide what kind of without! You time and money how thick foam board for basement walls you need there must be a magazine subscriber to access this feature and... And draftstopping complete stucco or brick veneer the long run, the higher the chance of condensation..! Time in most regions get the job done right against the rigid foam, use lumber. Right tools cost for a shopping list and tools subscribe to this RSS feed, copy paste! Keep uranium ore in my opinion my basement finishing project be much more cost-effective to buy a single or... Rockwool and then return later to tape all seams best insulation for the foam sheeting you need a minimum R-10... My research on the inside of a wall for a capillary break 9 2012! To R5.5-R6 be a magazine subscriber to access this feature has been temporarily disabled during the site! For siding: //publicecodes.cyberregs.com/icod/irc/2012/icod_irc_2012_11_sec002.htm insulation for the basement walls before putting in studs, insulation sheetrock! Up against the walls and rim joists all seams job done right as the summer this site time in regions... Acting on it am foggy on what to do insulation for the Floors in to... A minimum of R-10 on the assumption that there is no issue with the! A HTTPS website leaving its other page URLs alone cover them with an barrier. Is giving you is for basements so i ’ ve installed thousands of the insulation job right first... 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