How to Install Western Cedar Siding: Part 2 - Door and Windows Flashing

The main use of flashing window and door headers is to cut off water behind the siding and direct it to the outside, and to forward water flowing down the face of the wall away from wall opening.



Moisture can build up behind the siding because:

• The rain penetrate through the siding;
• The water vapor diffusion;
• Moist air leaks from the interior or the condensation.

Some moisture will drain through the weep holes at the bottom of each piece of siding.

An additional head trim flashing is needed at the windows or door headers to make the water go further outward, beyond the thickness of the windows.


Ground Level Skirt Board



Second Story Bandboard


Read How to Install Western Cedar Siding: Fascia Flashing - Part 3