How to Make Screens for Foundation Vents for an Old House

Remove the existing vent material with pliers, wire cutters, tin snips and a hack saw. Clean up the inside edges of the foundation to remove all loose debris and dirt.

Measure the opening. Cut 1-by-1-inch cedar boards to fit the opening. Miter the corners using a flat saw and miter box. Place the corners together. Drill through the ends and screw the mitered corners together with two wood screws at each corner.

Fit the wood frame into the opening. You want the frame to be snug and well fitted but not tight.

Place the frame flat on the work table. Cut metal insect screen four inches larger than the frame on all sides. Position the screen over the frame. Staple the screen to the frame along the outside edges. Stretch the screen across the face of the frame so that it is taut. Staple from the center toward the corners. Fold the metal mesh at the corner so that the fabric overlaps but isn't bulky. Staple the mesh. Cut off the excess fabric.

Cut 1/2-inch metal screen four inches larger than the frame. Press and fit the screen over the first screen. Staple along the sides from the center toward the corners. Trim off all excess material to create a snug corner fit. Trim off any remaining excess fabric.

Position the vent in the foundation hole in the direction you prefer. Typically the vent will be inset at least 1/2 inch from the front face of the foundation. When you like the fit, apply silicone exterior adhesive along the sides of the vent and along the foundation walls at the location you want the vent. Press the vent into the silicone. Wipe off excess with rags. Apply a second bead along the joint between the wood and the foundation. Smooth the joint with your fingers.