Insulating Basment Walls

[Larry Frank]

One wall of my shop is poured concrete which needs to be insulated. With the cold weather recently in this area and temps down to 5-15°F region, the walls are very cold and it is difficult to heat (and expensive). I have searched several places and found the most recommended is the following -

1-1/2" foam insulation board (pink) glued to the concrete and the joints taped
Stud the wall out and fill with R-13 fiberglass insulation and with kraft paper toward the warm side of the wall
Drywall over the studs ( I may just use pegboard.

I have read several different thoughts on a vapor barrier. I do not have a water problem on this wall and so will not use a vapor barrier except for what the kraft paper side of the insulation provides.

I hate losing 6" of my shop with the insulating and wall but this provides the best insulation.
What have other people done for basement walls?

[Dick Thomas]

. . .
1-1/2" foam insulation board (pink) glued to the concrete and the joints taped
. . .

Larry, don't even think about it!!! The pink - or any other color - rigid foam IS NOT FIRE SAFE! Just like fiberglass, it must be covereed with a fire resistant surface = drywall. (NOTE: Pegboard over fiberglass won't be safe either: If you want pegboard, you'll have to drywall first) My approach was to rip nominal 2x3's to 1 1/2 x 2" (actual depth, since I had a supply of 2" foam; in your case, rip to thicknes of the foam you buy) and shoot these studs onto the concrete @ 16" centers. Then cut the foam into strips (score with a sharp knife & break over a square edge) and press fit snugly between the studs; Then drywall normally. Since it's not a structural/fire-block wall, you don't have to tape & mud the joints except for your own asthetic choice. Also,

RE: "I hate losing 6" of my shop with the insulating and wall . . . " since the wall is not load bearing, there is no need for a full 6" depth - just insulation + 1/2" drywall.

[Dan Hintz]

Larry,

That is exactly what I did... 1.5" extruded foam panels against a block wall, followed by 2x4 studs set 1-1.5" away from the foam to allow for easy runs/changes of utilities. When finished, it all gets drywalled over (it's not legal or safe to leave the foam unprotected).

I highly suggest Dry-Lock before putting up the foam if you're underground. Also, you still need fireblocks (unfaced rock wool or fiberglass is fine) every 10' in the vertical studs, and any horizontal runs (like joist runs above) should be blocked.

[David Gutierrez]

Actually fiber glass is non combustable and there is no requirement for it to be covered by drywall. The drywall is there to provide fire resistance for the wood studs not the fiberglass.
To minimize the loss of space use 1 1/2" studs steel or wood, 1" foam insulation and drywall.

[Dan Hintz]

Actually fiber glass is non combustable and there is no requirement for it to be covered by drywall. The drywall is there to provide fire resistance for the wood studs not the fiberglass.
To minimize the loss of space use 1 1/2" studs steel or wood, 1" foam insulation and drywall.

The fiberglass isn't combustible, but the extruded foam is... therefore, it has to be covered with drywall to keep a proper fire rating. You can't count on the fiberglass remaining within the studs by friction fit (and the stapled paper will burn off), so once a piece falls out the extruded foam is revealed... drywall is necessary.

[james glenn]

I actually used some rigid panels that have a fire retardant felt paper surface.
It is actually for flat roof insualtion in rated systems.
Just glue and stick, it's a nice blackish color and if you get the joints tight, doesn't look bad at all.

It's 2.5" thick.

[David Gutierrez]

You are correct i did not read the orignal post correctly. i thought he was proposing two solutions a foam or batt not both in one system.
drywall is required to cover either the foam or the wood studs and fiber glass has no fire rating.

[Pat Barry]

I like the foam over concrete as a base followed by the framed up wall and finished with drywall Sticking studs directly to the block / concrete is way more trouble than its worth - the concrete / block isn't level so you need to do a lot of shimming and it only saves you a couple inches. Frame up the wall and stand it up and you can build it real fast. I'm in Minnesota and regret not putting in the thicker, better insulated walls in my lower level. You will appreciate the better insulation immensely.

[Jeffrey Makiel]

I would consider the new mildew proof drywall too. I have no experience with it, but I wished it was around 20 years ago.

Moisture can come through the concrete from outside, or from the warm side of the room via condensation. Vapor barriers and basement waterproofing helps fight this moisture. But, basements are also the lowest point in your home, and if anything leaks (fish tank, toilet overflows, water heater pops, washing machine hose lets go, etc.), it inevitably ends up in the basement.

-Jeff

[Shawn Christ]

Moisture can come through the concrete from outside, or from the warm side of the room via condensation. Vapor barriers and basement waterproofing helps fight this moisture.

Agreed, the vapor barrier won't help with leaks but will protect from condensation behind your new wall. If a warmer shop is your goal that could mean higher humidity which could cause more condensation on the cold concrete wall. Based on my experience vapor barriers are common practice in this area. Draping an inexpensive sheet of plastic against the concrete behind your wall should do the trick.

[Jonathan Link]

This is also the subject of an article in the FWW Tools and Shops issue, #216.
Short of it, gluing foam 1.5"x4'x8' to the wall between 2x3's nailed flat to cinderblock wall for top and bottom plates. Attach 2x4 studs nailed flat to top and bottom plates 24" on center, fill with foam insulation between studs. Cover with drywall. The first layer of insulation was notched for conduit.

I'm probably going this route to insulate my garage...

[Jarrett Vibert]

I just finished taping up the seems on the rigid insulation I put on my basement walls. Keep in mind that if you seal all the seams and fill gaps with spray foam it will double as a vapour barrier. Thereby creating a thermal/vapour break from the concrete/block to your studs and drywall. So as long as you don't add vapour barrier between the drywall and studs, they will be within the warm zone and not suffer from moisture issues non related to actual leaks.

I will also fill stud cavities with standard fiber glass insulation, but at this point that's mostly for sound absorbtion, as the rigid board does an equalily as good a job as the builder pink wrap they used originally.

[Bruce Wrenn]

For studs, consider metal. They are easy to work with, and termites don't eat them either. But if exposed to moisture, they will rust.

[Michael Heffernan]

Here's what I did in my garage woodshop. It is block and brick construction. Glued Foamular 1" thick, 2'x8' tongue and groove rigid foam (pink panels, available at HD) to the block. Tapes all the seams with Tyvek house wrap tape (cold weather foil tape works just as well, but a little more expensive). Sealed gaps at the concrete floor with low expansion spray foam and scraped off the excess. This sealed the walls from vapor penetration.
Fastened 2x4 pressure treated sill plate to the concrete floor, with sill foam between the plate and the slab. On top of that, I built conventional 2x4 stud walls, 16" O.C., attaching to the PT sill plate and ceiling joists. Ran my wiring through the walls, filled the cavities with R-13 insulation and covered it with 1/2" BC plywood. A couple coats of off-white paint finished it off. I like the plywood walls for mounting and hanging anything, anywhere. My last shop I installed drywall, and though it is a cleaner look, it gets dinged up more easily and you need to find the studs for most mounting applications.
I also put an insulated floor on the slab, using 2x4 pressure treated sleepers (laid flat) and PT shims, 16" O.C., filling the bays with 1.5" rigid foam, with 3/4" plywood decking.
With R-18 plus in the walls and R-8 plus in the floor, it's relatively vapor tight and warm.

[Chris Damm]

What I did (and it has held up well since 1983) is to attach a 2x2 nailer at the top and bottom of the wall, add 1.5" of foam, and then glue and nail drywall to it. Make sure the dryall seams don't line up with the foam seams. You can't attach any thing heavy to the walls but it insulates the walls very well without taking a lot of floor space. I surface mounted the electicals. I believe Owen-Corning has now come out with 1.5" foam with a dodo for a 1x4 nailer which work even better. Check out Hometime site, thet used a garage they coverted to a workshop.