Concrete Floor Rehab Advice

[escrivner]

Help and advice is needed. My son and daughter-in-law have an old stand alone 3 bay garage they use for shop/woodshop/vehicle storage. We will be insulating the walls and roof, but need advice for the concrete floor.

We live in the Pacific NW where it is wet most of the winter but not too terribly cold. Do we need to insulate the floor and apply a subfloor over it? Will insulating the walls and roof mitigate the floor feeling cold? We are worried about the John Deere and SUV compressinig the foam when driven into the garage.

 

[Shiftless]

Are you planning to heat and cool that space?

 

[FMB4]

Can't help you with your questions, but welcome aboard!

 

[Riley]

I'm a bit confused. Are you pouring a new floor in an existing building or rehabbing an existing floor? From what I've read here over the years, a couple inches of foam under a slab has no ill effects. I don't think insulation in the ceiling and walls can mitigate a cold floor. Insulation under the slab, and radient heat do that best.

 

[ConCretin]

Since you refer to parking things on the slab, I assume it will remain a garage and the 'subfloor' you refer to would be concrete to cover insulation installed on top of the existing floor?

The answer to your question is NO, you do not need insulation under your slab(s). Unless you are in a cold climate and have in-floor radiant heat, the payback would be longer than you or your son are likely to be around. In addition, I doubt you'd even know if it was there or not under most conditions. In some conditions it might even be a detriment because it blocks the natural heat from the ground, which might otherwise be helpful.

 

[escrivner]

This is a rehab of an existing garage with concrete slab floor. The space will be heated.

The question we have is how to insulate the floor (or is it even necessary) and still park the tractor or other vehicles inside to perform maintenance? Would it be OK to use 3mm closed cell foam underlayment and 3/4" or 1" T&G plywood for a floor? Would the 3mm foam give us enough thermal break to justify the cost?

 

[escrivner]

I'm a bit confused. Are you pouring a new floor in an existing building or rehabbing an existing floor? From what I've read here over the years, a couple inches of foam under a slab has no ill effects. I don't think insulation in the ceiling and walls can mitigate a cold floor. Insulation under the slab, and radient heat do that best.

Sorry i was not more clear. This is an existing slab in a 3 car garage.

 

[escrivner]

Are you planning to heat and cool that space?

yes to heating the space.