NASCLA Accredited Commercial General ContractorMasonryHard
A contractor is installing through-wall flashing in a brick veneer cavity wall. To ensure effective moisture management, how should the through-wall flashing typically be installed relative to the weep holes and the exterior face of the wall?
- AIt should be installed vertically within the cavity, parallel to the wall faces, connecting the top and bottom weep holes.
- BIt should extend from the interior face of the backing wall to the interior edge of the weep holes.
- CIt should extend from the interior face of the backing wall, across the cavity, to the exterior face of the veneer, with a slight slope towards the exterior.
- DIt should extend from the exterior face of the veneer to the interior face of the backing wall, sloped inwards.
Show answer & explanationAnswer & explanation
Correct answer: C. It should extend from the interior face of the backing wall, across the cavity, to the exterior face of the veneer, with a slight slope towards the exterior.
Through-wall flashing must extend from the interior face of the backing wall, across the entire cavity, and project slightly beyond the exterior face of the veneer (or terminate flush with weep holes). It must also be sloped towards the exterior to effectively direct water out of the wall system via the weep holes.
Why the other options are wrong
- A. Flashing is installed horizontally (or with a slight slope) to divert water, not vertically to connect weep holes.
- B. This would trap water within the cavity, as it doesn't extend fully to the exterior.
- D. Sloping inwards would direct water into the interior wall structure, defeating its purpose.
Through-Wall Flashing Installation
The proper placement and extension of a water-impermeable membrane within a masonry wall to intercept and redirect moisture out of the wall assembly.
- Extends from backing wall, across cavity, to exterior.
- Must have a slight slope to the exterior.
- Placed above openings, at base of cavity, and other moisture-prone areas.
- Works in conjunction with weep holes.
Memory trick: Flashing is the 'slide' for water to exit the wall.