Stem Wall Concrete Insulation

[m123]

I am building a 40x40 detached garage with a 6" concrete wall exposed above grade and above the finished floor (finished floor not poured yet). Midwest cold winters, and would like to know the best way to insulate this short wall above grade. I have taken the advice of others to have the wall stick up above grade so that I can wash out the floor if needed and also to help prevent the sill plate from deteriorating.

I have the question about insulation. I will have 2x6 framed walls sitting on this wall, and will consider either fiberglass or spray foam (or both).

My question is how to insulate this 6 inches of concrete above the finished floor/final grade? I don't really like the look of rigid insulation on the exterior of the garage.

 

[Leaflessshadetree]

Most people don't worry about it and leave that 6" uninsulated.
I'm going to insulate it on the inside. 2" rigid insulation. I haven't decided on interior covering but am considering aluminum or some type of plastic.

 

[Westbank]

I'm also looking for a solution to insulate on the inside. Logically, foam boards insulation is the best option but foam boards have to be covered with fire rated material (such as Fire Code drywall or the boards have to be fire rated). There are not many options available for fire rated boards. Dow has the Thermax boards but they are hard to get.

I was thinking of installing foam boards and gluing / screwing a PVC sheet to cover the foam board.

 

[Always_Thinkin]

No need to worry about insulating the 6" stick up of concrete stem wall. I would recommend sealing the perimeter joint that will exist around the top of your floor that buts up against the stem wall. You can get a concrete joint sealant at Lowes, HD etc.

 

[Westbank]

No need to worry about insulating the 6" stick up of concrete stem wall. I would recommend sealing the perimeter joint that will exist around the top of your floor that buts up against the stem wall. You can get a concrete joint sealant at Lowes, HD etc.

During winter if he's heating his garage that could be an issue. Frost will build on the concrete especially in the corners.

 

[m123]

They are going to put 2" foam around the perimeter of the slab and on the inside wall before we pour, so that should help, but I'll still have a short piece of wall exposed. I wonder how bad it would look if I did spray foam for the wall cavity and just had them continue down the wall from the sill to the floor. Closed cell is supposed to resist water, but I have a feeling it might be ugly.

Now I really wish they would have just put a piece of foam in the wall before it was poured. Too late now.

 

[theoldwizard1]

I would not worry about insulating that 6" unless you are planning on insulating under the floor. Then you need to run 2" rigid foam board from the top all the way down to the frost line on the outside. Paint it.

Even if you do not plan on insulating the floor, put down a vapor barrier. It will make the garage less damp in the long run.

 

[Orionrising]

Insulate with foam board and cover with stucco or trim metal if you are heating in a cold climate even if no underslab insulation. Big difference in heat transfer to a slab sitting on 50 ground and exposed concrete in 20 below air

Sent from my Moto G (4) using Tapatalk

 

[wssix99]

I don't really like the look of rigid insulation on the exterior of the garage.

I'd definitely cover it with siding, then.

You could just run the foam board all the way up the full concrete and framed wall and then side over it. You can use aluminum to skirt the lower portion below the ground.

I have an ICF house, so we have foam covering 100% of the house and this is what we've done. ^

 

[gnpenning]

Insulate it! Cement is a great conductor for cold transfer to the inside and heat. Like above I have a ICF home. The easiest and best way would to form your wall with ICF's. Otherwise take your foam board as far down in the ground as you can. Use a ridged foam. As mentioned cover with metal, plaster or stucco.

Anytime you can stop the cold from coming in you will be ahead of the game.

I made the mistake of not insulating the short exposed foundation wall many years ago, by people that supposedly new what they where doing, and will never do that again. I've done it both ways and there is a difference.

 

[Jlbc212]

I would leave the concrete exposed. Anything up against the concrete will hide termites, carpenter ants and other vermin as they tunnel up to your sill and 2x6 framed walls.

 

[K'ledgeBldr]

Exactly how much of this 6" poured wall will be exposed above the floor?

If some forethought had been used someone would have known to do the wall a different thickness to compensate for the insulating board-

At this point, you have three choices- leave as is, make the wall 2X8's and achieve the same result or, apply insulating board to the interior and cover it with some other material.

 

[ALinCarolina]

This is what I am doing for my slab and wall: