Insulating interior foundation walls (above grade)

[Westbank]

I’m currently trying to figure out the best option to insulate the interior foundation walls (above grade). Foam board insulation is the best option but since it will be installed on the interior side it would need to be fire rated. As per local building code, foam insulation 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’m in Canada and I still haven’t found a retailer.

The problem I need to solve is frost buildup (due to condensation) on the foundation walls (mostly corners) during cold winter days (-20 Celsius / -4 Fahrenheit).

Any other options available for this application?

 

[Voi]

Any other options available for this application?

There are coatings designed to be applied over foam that have a fire rating but you'll have to see if they're acceptable in your area.

 

[Westbank]

There are coatings designed to be applied over foam that have a fire rating but you'll have to see if they're acceptable in your area.

Most coastings are ignition barriers not thermal barriers.

 

[Corsair4360]

We used to live in North Dakota and had 4" of frost inside the basement wall corners where the walls were exposed when it got very cold the first winter we lived there. I put in a cripple wall of 2x4's spaced 2" out from the concrete with insulation in the wall (fiberglass). The basement went from cold to very cozy. Not sure if that helps. Another potential fix, is to use the insulation foam boards and cover it with two layers of 5/8" sheetrock, which is a fire wall.

 

[sands35]

Why restricted to the inside? Outside and you just need a damage barrier from weed-eaters. Might have to wait until spring to put it on though.

If on the inside, then it gets complicated to manage water and condensation.