There are two different types of brick houses in Ontario, brick veneer and solid masonry.
Solid masonry construction is also called ‘Solid Brick’, ‘Double Brick’. A solid masonry wall consists of an outer layer of brick and an inner layer of brick (a layer of brick is called a ‘wythe’ ).
These types of bricks (header bricks) are installed, usually every six rows to hold the two rows of bricks together. From the outside, header bricks look like regular bricks except they are shorter. The header bricks act as a bridge joining the two rows of brcks and prevents them from separating.
Most brick houses built in the last 30 years or so are brick veneer. Brick veneer is a single row or layer over bricks with a one inch air gap between the bricks and homes framing.
Brick is not waterproof
Although many may think that brick construction resists water, it doesn’t take much for it to pass right through. The air space behind the brick allows this water to run down the back surface of the brick. At the bottom of the wall cavity, a metal flashing collects the water and allows it to drain out through weep holes. These are the openings in the lower levels of bricks and along the top of foundation walls and above doors and windows.