Frost at top of basement concrete walls

dtabor

The last couple days we have had -20 to -30 degree temps overnight. I noticed that as soon as the temps started dropping in one end of the basement, on the unfinished, poured concrete walls there is actual frost formed!! It extends from the top of the concrete wall about a foot to foot and a half down. Originally I thought this was caused by the need to seal around the top of the sill but I wouldnt think it would extend that far down if it was a draft along the sill?? This is my 3rd winter in this house and Ive never seen this happen until this year.

Additional info, the basement is unfinished all around and unheated other than residual heat from the furnace or pipes. In the area of the frost, the outside of the wall is exposed on one side of the house about a foot or two and on the other wall it is under my porch and is exposed about 2 feet or so.

What is causing this frost and how might I resolve the issue?

Thanks

D

Bondo

Ayuh,....

Concrete is a Lousy insulation,...

Waiting til the Temps get up to 0°,+ it will no longer be an Issue.....

Bob Mariani

Below grade a foundation wall vents to the inside of the basement. Above grade it vents to the outside. This small heat in your basement is warmer than the outside air, thus condensation which is frost being chilled to the freezing point. Place foil-faced foam insulation on the inside of the wall above the ground level and this will stop

II Weeks

or take it a step further. where your water is coming into the house is roughly 1' or so below what your area deemed the frost line. Thats how far down basement insulation should go and most people nowadays use rigid board.