Foam board insulation is a DIY friendly product that any home owner can easily work with with limited tools and experience. Best of all the product is relatively safe to work with and won’t cause side effects like fiberglass insulation or spray foam. XPS foam insulation can be cut with a utility knife, handsaw or table saw easily to fit any configuration.
The key to a successful installation is sealing all the joints and gaps. Typically we like to seal the joints with Tyvek tape. The larger gaps are typically sealed using spray foam from a can like Great Stuff. Sealing the joints helps stop air infiltration and provides for the most effective vapor barrier possible.
Foam insulation is perfect for basements because it won’t promote mold growth, won’t decay, won’t absorb water (closed cell) and it has great insulation R values. Foam board insulation can also provide a very good vapor barrier to prevent the movement of moisture from damp basement walls.
The biggest reason we like foam board insulation is the cost savings. DIY foam insulation can save significant money compared to professionally installed spray foam while maintaining some of the great benefits that foam offers. Installing the product yourself can save as much as 60% or more compared to spray installed.
DIY projects can be fun and cost effective. Working with foam board insulation is really easy and it’s a project that inexperience DIY’ers can tackle. Be sure to check with your local code officials on energy code requirements to be sure you’re installing a sufficient amount of insulation. Have fun and enjoy your warmer basement!
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While I agree that foam board can be done by a DIYer, the insulation value would be considerably less than a spray foam application because of the many joins. Sealing them with tuck tape just isn't the same.
But then again, what else could a homeowner do? The do-it-yourself spray foam kits are expensive and create considerable waste.
SD
@ Steve - I actually don't really agree with you. When you use T&G foam board and seal the joints it works very well. I've even seen thermal imaging of it and it does perform.
Great post!
I have XPS foam insulation in my home and I have no complaints. My energy bills have dropped and the house feels warmer.
Cheers.
Todd,
Can I double up on Polyiso rigid foam board? I have a walk-out basement with a 2 x 6 load bearing back wall and am considering using two layers of 2.75 inch Polyiso to get the most of the space.
Joe - Sure can!
Even if it is faced on both sides? Should I be worried about moisture or condensation?
Joe - I really don't think it's a big deal. Moisture won't hurt the foam even if it gets trapped between layers.
Excellent!! Thank you for your help. I was more worried about any condensation having an adverse effect on the wood framing. I do plan on spray foaming the rigid foam in place. You have been very helpful.
I have cathedral ceilings (2X12 rafters) and am trying to get as close to R-50 as possible and that seems to mean "foam".
While there seems to be a plethora of DIY foam kits out there they appear to be more expensive than just hiring a contractor to come out and spray it.
Are there any less expensive options I have overlooked?
Thanks,
Randall
Randall - DIY kits are becoming hard to find and expensive as the Government cracks down on the practice due to health concerns. You can probably get an R50 in other ways. Recently we had a customer who chose to install proper vents for the entire length of roof followed by 12 inches of fiberglass in the joist bays. Next we installed 2 inches of foil faced polyiso. Then the ceiling was strapped and finished. That's one approach you could take.
I looked but could not find anything on your site that would show the pros and cons of doing spray foam as a DIY project. I have a 24" cantilever floor overhanging my walkout basement. Last winter that whole side of the house at the floor level was right out COLD. Not cool, but COLD. My kitchen sink's plumbing runs up through that space and I can only consider myself lucky that the pipes did not freeze. I have been looking at those DIY foam tanks. It seems I can get one set to do the that whole side of my house.
Why would I not do it?
Because the ground slopes down to the walk out, it would be difficult, at best, to get under the cantilever section the whole length of the house to take off the underboard and use foam board and tuck tape.
I think it would be much easier and faster to spray it from inside.
Can you give me some dos and don't or pros and cons?
Thanks,
Fred
Fred - Most DIY kits are now banned from sale to private homeowners. Having said that, if you can find one this is the size of job that works best for most DIY applications.
i am insulating my concrete basement walls and put up 1 1/4th inch underlayment board - fanfold directly on the concrete walls and then atached the furrign strips. shoudl i now put the 3/4th inch foam board between the furring strips. The 1/4th inch is only rated R-1 so although i am in the south i need more insulation.
Jeff - I would put up 1-1/2" foam directly on the firing strips so there are no gaps, tape the seams well. Then you can attach wall covering directly over the foam with longer nails/screws into the firing. Good luck.
I am repairing a cracked, leaking, and crumbling foundation. I am getting ready to start backfilling very soon. I have a fibrous asphault sealer applied to the oustide walls. I was wondering if applying styrofoam insulation sheets that I have pruchased directly to the sealer would cause a problem, like if the asphalt (petroleum baed product) will eat away at the the styrofoam. I am doing this on the outside of the house and will be putting vapor barrier over the outside of everything but thinking about applying it between the sealer and styrofoam as well. Thanks, John
John - I wouldn't recommend it. I would recommend installing something more like the WARM-N-DRI® Foundation Board that TUFF-N-DRI system uses. I think the foam will break down.
Hi, Todd,
Where can I get foam insulation that is cut to 14.5", to fit into stud bays? I want to insulate a small shed, and don't want to use fiberglass or other batting type stuff. The studs are 2X4.
Thanks,
Bill
Bill - You'll have to buy 24" or 48" wide sheets and rip them down on a table saw or some other saw.
Even if I had a table saw (nope), there would be a lot of waste; 9.5" of waste from each 24" width, and 4.5" from each 48" piece. I would think that only a table saw would produce a decent and uniform cut. I envision making a tight fit into the bays, so as to get the best insulating value. Also, would like to get a tight fit so to help hold the panels between the ceiling joists. Thanks for the reply.
Bill - We usually use spray from from a can to hold the panels in place. It acts as an adhesive and insulating value.
This info is really helpful, thanks. My question is about adhering the XPS to a foundation wall that has bumpy seams and even 1" bumps from the form ties. Should I take the time (and mess) to clean all this stuff off, or will the foam dent enough so it is not held away from the cement? Or, is spray foam really the most practical option?
Finally, will just 2 inches (R10) of foam be adequate, without the layer of fiberglass? I live in Vermont...what R should I be shooting for? Thanks!
Philip - Thanks for the compliment.
Typically we knock off really high stuff, the rest doesn't matter. You can push the foam onto the lower stuff. Great Stuff Pro works VERY well for adhering it.
The R value question depends on numerous things including energy codes, cost and overall comfort. 2 inches does pretty good in most basements.
Good luck.
Thanks Todd. How is Great Stuff Pro different from regular ol' Great Stuff (greater, I presume)? And wouldn't a spray foam like that actually lift the board away from the cement?
Philip - Great Stuff Pro Wall & Floor Adhesive (http://building.dow.com/na/en/products/sealants/gspwallfloor.htm) is specifically made for adhering products to walls and floors. It may slightly lift it up but that's really not all that important. What's most important is getting good seals at the seams and creating a good air tight insulation layer.