Pyrite can lift a basement slab and cost a lot. Here is where it is found in Quebec, how to recognize it, and what it changes when you buy.
What is pyrite?
Some backfill under basement slabs contains pyrite. In the presence of moisture and oxygen, it swells over time and pushes the slab upward.
Where in Quebec
Several areas built on backfill, the South Shore, Montérégie, Laval and surroundings, are affected.
The signs
- Star-shaped cracks in the basement slab.
- Floor lifting, doors that stick.
- Cracks in the foundation walls.
The test
Confirmation is done by a petrographic test (IPPG index) on a sample of the backfill, in an accredited laboratory.
Impact when buying
Knowing the extent of the problem gives you negotiating leverage and avoids a costly surprise.
Frequently asked questions
Detectable during a visual inspection?
The signs can be spotted; confirmation requires a laboratory test.
Can you buy despite pyrite?
Yes, as long as you know the extent and the cost.
