Installing an exterior window casing is a simple process that can be complete within a few minutes if the proper materials are available. You need a hammer, several nails, a caulk gun, and the strips of wood to be used as the casing.
- Nail the top and bottom strips into place
Take the top strip of wood and place it on top of the window frame. A strip of the correct size should extend out slightly past the window to compensate for the extra width the side pieces add. Nail this strip of wood to the stud framing by hammering in a nail every six inches. Repeat this process for the bottom strip of wood.
- Nail the side pieces into place
Examine the strips of wood you are using for the siding. These should be able to slide in between the top and bottom strips. Slip these two pieces into place, then hammer them so that they are fixed. Use one nail every 6 inches.
- Apply caulk
Use your caulk gun to run a bead of caulk around all sides of the exterior casing. If you can see any cracks, holes or gaps in the wood, fill them in with the caulk gun as well.