Installation of Architectural and Building Envelope Products
What this domain tests
This domain covers the weather side of the trade: roof drainage, flashing, wall cladding, soffit, fascia, and coping. Items test water control, thermal movement, and the fire, wind, and air-barrier requirements that decide whether an assembly passes inspection.
Water control fundamentals
- Laps run in the direction of flow, with a minimum lap of about 100 mm (4 in.) on roof work.
- Base flashing runs up the wall, counterflashing laps over it, and the top edge sits in a reglet or under the cladding. The two are not rigidly sealed to each other where movement is expected.
- Gutters are sized to roof area and rainfall intensity, with hangers, expansion joints, and outlets spaced to code and manufacturer requirements. Downspouts discharge to splash blocks or storm drainage, never onto the wall.
Cladding, panels, and movement
- Metal wall panels are installed as a rainscreen over the air and vapour barrier; continuity of the barrier matters more than the panel.
- Aluminum expands about 13 x 10 to the minus 6 in./in./F and steel about 6.5 x 10 to the minus 6, roughly double. Panels are fixed at a fixed point and allowed to move through clips, slots, and lap joints.
- Sealant joints need backer rod to set depth and prevent three-sided adhesion. Width-to-depth is typically 2:1, and the sealant must be rated (ASTM C920) for the movement expected.
- Wind uplift resistance comes from a tested assembly (ASTM E330, UL 580) and the specified fastener pattern.
Worked example: expansion allowance
A 24 ft aluminum coping run is installed at 60 F with a design surface temperature of 160 F, so delta T = 100 F. Delta L = 288 in. x 13.1 x 10 to the minus 6 x 100 = 0.377 in. Provide an expansion joint or end clearance of at least 3/8 in. per run, or the coping buckles or pulls its fasteners. A 48 ft run needs 3/4 in.
Traps that cost marks
- Sealing the bottom of a panel joint and trapping water.
- Fixing both ends of a long run and leaving no room for movement.
- Three-sided adhesion in a sealant joint because no backer rod was used.
- Steel fasteners into aluminum or copper.
- Reversing laps so water runs into the joint instead of over it.