Brick Mold Casing
1 - Cut Brick Mold
Cut the necessary lengths of your brick mold casing with a minimum of 1” more than than the dimensions of your pet door + 2x the width of your brick mold casing.
Example – if you are using a medium pet door, it is 12.25” wide x 17” tall. Standard brick mold casing is 2” wide. In this scenario you would cut brick mold casing to be at least 17.25” (12.25” + 2 x 2” + 1”) wide and at least 22” (17” + 2 x 2” + 1”) tall.
2 - Initial Miter Cuts
Align the pieces in to make the rough shape of the frame, and mark the needed angle of the cuts on the ends. These marks are only used to ensure that there are no mix-ups in the direction of the cuts, not as precise cut lines.
Miter each of the pieces at a 45-degree angle at the marked end as close to the end as possible. Ensure that you get a full-width cut.
3 - Screw Together Mitered Corners
Using appropriate outdoor-rated screws, screw together the mitered corners. The use of pre-drilling and counter-sinking are recommended, as is the use a a material-compatible sealant.
4 - Final Miter Cuts and Assembly
Decide whether you want a tight fit for your brick mold casing or small space for material expansion. If you are not certain that your brick mold casing material is the same as the cellular PVC used for the pet door frame, you may want to consider leaving the expansion space. This is what is demonstrated in the video.
Place one of the brick mold casing assemblies against the pet door (with shims if expansion space is desired) and mark cut lines on the opposing end. Repeat for the other assembly.
Mark on the pieces the rough angle of the cut for clarity while at the saw.
With absolute precision, make the final miter cuts at the length indicated by your marks.
Dry fit the pieces, and then assembly squarely with screws as before.
5 - Attach Brick Mold Casing to Pet Door
Open the flap towards the exterior, and place the pet door on a flat work surface exterior (flap side) down with the flap hanging over your work surface.
Mount your picture frame to your door with exterior-grade screws. Use shims to ensure a minimum of 1/4” (6 mm) setback from the front of the pet door. Pre-drilling holes is recommended. Use shims to maintain expansion gap if your picture frame was built to accommodate one.
6 - Seal
Run a bead of material-compatible sealant around the entire back perimeter of the frame between the frame and the door.
Repeat on the front, but do not seal around the bottom. This is to allow for incidental water to escape to the exterior.
Allow to dry, and then proceed with the rest of the installation process.