A frost boil is a phenomenon commonly observed in masonry walls in Montreal when the repointing work has been neglected or due to ground movement.
In fact, it’s a detachment of the masonry cladding from its structure, hence the appearance of bumps or bulges in the wall that resemble a cow’s stomach.
Generally speaking, when the joints are open, moisture will attack the anchors and cause them to rust.
Over time, the anchors will give way, and the wall will start to deform. If they aren’t treated, the frost boils can cause the wall to collapse.
It’s possible to reinforce the frost boils with structural anchors in order to extend the useful life of masonry walls in Montreal by a few years.
If the deformations of the walls are too significant, however, you’ll have to disassemble and reassemble these walls to give them back their original verticality.