Masonry Flashing - Wall Base
At the base of the exterior facing, at the junction between the bricks and the foundation walls, there is a sealing system composed of a basic masonry flashing, an air barrier membrane (or coating paper) and weep. This system must be installed so as to prevent water infiltration into the interior of the building.
Sealing system (brick facing base) according to CMHC and APCHQ
In the case of a brick back wall attached to a wood frame wall, the masonry flashing should rise behind the sheathing paper or membrane approximately 150 mm. This is to prevent water from running off the paper and getting behind the flashing. Let us mention that chantepleures provide ventilation and water evacuation. They are laid out in the starting row of the masonry siding, leaving a vertical joint without mortar every 32 inches.
This waterproofing system at the base of the exterior cladding is not recent, even in the National Building Code of 1960 or 1965, the flashing at the base of the brick was already provided as well as the weepers. These elements are essential to prevent water infiltration, inside the building, and evacuate water to the outside.
Generally, in relatively old buildings (prior to 1970), it is observed that the waterproofing system at the base of the facing is defective. This situation creates problems of water infiltration, towards the interior of the building, at the junction between the exterior facing and the foundation walls.
To solve these water infiltration problems and prevent rotting of the wooden structure located above the foundation walls (foundation rail, edge joist, intermediate coating), a qualified mason must make the following procedures or works, namely:
- Support the brick walls and remove several rows of bricks at the base of the facing;
- Replace the waterproofing flashing at the base of the siding;
- Check the air barrier membrane and make the necessary corrections if necessary;
- Slide the base flashing behind the air barrier membrane according to good practice;
- Make the system waterproof before installing the bricks;
- Create chantepleures in the first row of bricks respecting the rules of the art.