How to Install Exterior Trim

Intermediate Level

Window/door trim, corner boards, frieze, and fascia: material selection, joint methods, priming, and finish.

Materials Needed

PVC Trim (Cellular PVC)
Cedar Trim
Finger-Joint Primed Trim

Note

Prime all six faces of wood trim BEFORE installation, including cut ends.

Note

PVC expands significantly. Leave 1/16" per 8 ft at butt joints. Glue with PVC cement.

Note

Never caulk the bottom edge of window trim. Must remain open for trapped water drainage.

Choosing Trim Material

Cedar for natural beauty, FJP for value, PVC for zero maintenance. Most builders use all three strategically.

Window/Door Casing

Head casing first (extends 1/4" past sides). Side casings tight under head. Sill last, sloped 5° outward for drainage.

Sealing

Caulk horizontal and weather-facing joints. Polyurethane or polyether sealant — avoid silicone on painted surfaces. Two coats acrylic latex paint within 2 weeks.