Damage to foundation walls In some cases, the lateral thrust of the backfill will produce cracks in the foundation walls. This usually occurs in basement walls, and garage walls were since the pyritic backfill level (ippg) is high. The swelling may cause the building’s foundations to heave and thus cause serious structural damage. On the South Shore of Montreal this type of swelling is often seen in older house with have a high level of pyrite.  Call now for a free estimate to get your basement pyrite removal or garage pyrite removal. 514-594-2897