What Is a Through Wall

1. a Through Wall Flashing (TWF) Defined : Through wall flashing is above grade waterproofing. It protects specific areas within exterior wall assemblies and creates an impervious barrier for water to follow to the face of the exterior finish.

What is a thru wall?

Description: Through-wall flashing is used to divert moisture, which has entered the wall, to the outside, before it can cause damage. This flashing method is considered the most satisfactory method of preventing leaks except in areas exposed to earthquakes.

How do you install exterior wall flashing?

The flashing must include a drip-edge to direct any water that runs down the drainage plane away from the bottom of the wall. Weather-resistive barrier. Next, a weather-resistive barrier, such as building paper or house wrap, is applied to the wall, overlapping the base flashing.