Step 1
Measure the length and width of the existing porch windows. It’s all right if the newly made storm windows are a bit smaller than the actual window sizes as long they’re sized proportionally.
Step 2
Construct the storm window frames using 1-by-2-inch pieces of pine or oak, or purchase screen framing pieces at any local hardware store. Screen framing pieces snap together at the corners. Otherwise, a 1-by-2-inch piece will require mitering at the ends so the pieces can be glued and nailed together.
Step 3
Tape plastic shrink wrap to the newly constructed frame using two-sided bonding tape. The thicker the plastic wrap, the better. Cut off any excess.
Step 4
Create a seal or gasket material using long strips of polyethylene plastic. Fold the strips over to create a layering effect and place them along the back side of the frame. Staple the strips in place.
Step 5
Place the newly made storm window onto the frame of the existing window. Brace the storm window in place using swing cleats. Use a drill and wood screws to attach a cleat at each corner of the window frame so that a tight fit exists between the storm window and the frame.