Under the National Building Code of Canada the installation of windows, doors, and skylights shall conform to CSA A440.4:19.
There are four essential characteristics of a code-compliant pan flashing system
In order to better understand how to comply with this standard, it is important to define the role of flashings. Flashings are fixed to a building’s barrier against the elements before installing windows. Flashings prevent water from penetrating horizontal joints, which redirects water outside. For flashings to be effective, they must: