Installing exterior door and window trim

The window and door were prepped by installing blocking around the perimeters. This provides a flat, stable substrate on which to apply the urethane millwork.

When installing exterior door and window trim, to make sure they lasts for years use a material that stands up to the elements with minimum maintenance

Contractor Steve Roth creates custom window and door surrounds using urethane millwork. In this case, he used flat trim with a woodgrain finish from Fypon and a little of his own creativity to create surrounds and a crosshead to complement the home’s lodge-style look.

“The original exterior door and window trim had rotted and been replaced with vinyl J-channel, which looked terrible,” says Roth. “The urethane pieces I installed resist shrinking, splintering, rotting and swelling, so they will provide long-term beauty for this home exterior.

Exterior door and window trim installation, step by step

Step 1

Roth ordered his preferred material, plus enough premium adhesive to complete the project. His first step upon delivery was to paint the pre-primed material with one coat of exterior flat latex paint.

After measuring, cutting and dry-fitting the individual pieces, Roth applied adhesive before fastening the pieces in place.

Step 2

While the paint dried, he installed blocking around the perimeter of the windows and doors to match the thickness of the log siding material. The blocking was about ¾-inch narrower than the trim and provided a flat surface to attach the trim while also giving the appearance that the window and door trim was standing proud of the log siding.

Step 3

Roth used scrap to form a fillet and a keystone to dress up the crosshead.

With the paint dry, the next step was to trim the pieces to fit around and on top of the windows and doors. Roth chose to add a little flair himself and cut slight angles on either end of the crosshead, using a piece of scrap to cut a keystone to add to the crosshead.

Step 4

After dry-fitting the pieces to make sure everything lined up and all joints were tight, Roth applied construction adhesive to the back of each piece and secured them in place with deck fasteners.

After only a couple of hours of work, new window and door trim is complete.

Step 5

Once installed, he spackled the countersunk fasteners and touch them up with latex paint. The only tools Roth needed for the project were a miter saw, screw gun and caulk gun. Start to finish, it took just two hours to complete one window and one door surround.

Install wood blocking even with the siding surface before attaching the window and door trim pieces. This will make installation quicker and provide a more seamless appearance.

—By Rob Fanjoy