Why is my cinderblock foundation cracking after I installed insulation and a vapour barrier?

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How would I rectifiy problem of foundation wall cracks with finished basement?

Terry P Published: July 22, 2020, 7:07 p.m.Last updated: July 24, 2020, 12:34 p.m.

I have a cinderblock foundation in my house built in central east Ontario in 1983. In 1999 I finished the basement, with tar paper against the cement wall, then studs and four inches of batt insulation and then a vapour barrier and drywall. Two years ago I noticed cracking on the exterior of some of the foundation blocks, where the interior walls had been insulated but not on a portion of the basement walls that were not finished on the interior. I have dug down about a foot on the exterior walls and there is no cracking evident below ground level, on any part of the foundation. 

The interior  walls are in good condition with no evidence of moisture or mold. I was going to have the foundation walls parged however I am looking for a longterm solution for this and want to make sure that I am addressing the actual underlying problem. Would I have to remove insulation, vapour barrier and drywall on interior basement wall and eventually refinish the interior walls of the basement in a different manner to rectifiy this problem longterm?

Responses (2)

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Terry P July 27, 2020, 5:41 p.m. Reply

To me I see the source of the problem with the foundation due to the use of the insulation and vapour barrier on the inside basement walls. If the walls were removed (including tar paper, insulation, vapour barrier and drywall) would this be the best solution? I am prepared to live with unfinished basement walls. If I chose to finish the walls, could I refinish with drywall only on the studs (no insulation or vapour barrier) and would that work to regulate the temperature of the block wall? I will look into getting an engineer to look at the foundation.