How to Install Outside Corner Trim on a Building

Measure the wall from the foundation to the soffit, or gable above. Cut two pieces of 1 by 4 hardwood lumber to fit the corner from top to bottom.

Fit the first piece of trim to the wall, with one long edge, flush with the outside edge of the adjoining wall. Nail the trim in place with a pin nail gun, one nail every 6 to 8 inches.

Position the second piece, overlapping the first, so that the long edge is flush with the outside wide face of the first piece. Nail this piece to the wall, and to the edge of the first piece.

Caulk the seam between the two pieces with painter's caulk. Caulk along the edges of both pieces, filling the gap between the back of the trim and the face of the siding.

Apply a coat of oil base primer to the trim with a disposable brush. Use long, straight strokes in line with the wood's grain. Prevent runs and drips in the surface by spreading it as evenly as possible. Allow two hours for the primer to dry completely.

Brush on two coats of semigloss latex, in either a matching, or contrasting color to the siding. Match the siding for a subtle effect, or use a contrasting color for a more dramatic effect. Use a medium width, soft bristle paintbrush, spreading the paint as evenly as possible to prevent runs and drips in the finish. Allow the recommended drying time printed on the paint label between coats for best results.