Wall Construction, Wall Coverings, and Exterior Finishes
Wall construction, coverings, and exterior finishes
This domain ties the structure to the envelope. Walls carry loads, resist wind and seismic movement, and keep water out. Most exam traps involve water going the wrong way.
Concepts
- Stud size, spacing, grade, and height determine capacity; load-bearing walls need proper top plates, headers, and king and jack studs at openings.
- Wall bracing and sheathing resist lateral loads; fasteners and panel edges matter as much as panel thickness.
- The exterior wall envelope is a layered system: sheathing, water-resistive barrier, flashing, drainage plane, and cladding.
- Flashing at roofs, walls, windows, doors, and penetrations must shed water outward, with laps shingled in the direction of flow.
- Masonry veneer needs anchorage, a drainage cavity, and weep openings.
- Exterior coverings need clearance above grade and above roof surfaces, and fasteners must suit the material.
- Interior vapor retarders belong on the warm side of the assembly in cold climates-when required.
Traps
- Reversing the laps so water is directed behind the barrier.
- Sealing weep holes, which traps water in the cavity.
- Installing cladding tight to grade or roof.
- Using the wrong fastener or missing flashing at a penetration.
Worked example A window is installed with the head flashing lapped over the water-resistive barrier but the sill flashing tucked behind it. Water reaching the sill can run behind the barrier. The correct detail laps the barrier over the sill flashing and under the head flashing, so every layer sheds onto the one below.
Rule of thumb Think like a raindrop: every layer should overlap the one below, and every cavity should drain.