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Steps
1
Slide a drop cloth under the door to protect the floor. Leave the door on its hinges throughout the process.
2
Use a sharp utility knife to cut away ragged edges around the hole. Hold the knife at a slight angle and use a gentle sawing motion to remove roughness and create a beveled cut.
3
Crumple a small amount of newspaper or paper towels and push the wad lightly into the hollow area of the door around the perimeter of the hole to act as a block for the foam.
4
Spray low-expansion aerosol foam insulation into the hole using the provided straw, starting at the back and spraying slowly. Let it set for 10 to 15 minutes until it is no longer tacky but still soft.
Tip: Avoid high-expansion foam, as it can cause the door surface to bow outward.
5
Once the foam is fully dried, extend the utility knife blade and hold it flush against the door surface to trim away any excess foam that expanded outside the hole.
6
Scoop a small amount of fiberglass-compatible auto-body filler with a plastic putty knife and smooth it over the hole. Wipe off excess and let the filler dry completely.
7
Sand the dried auto-body filler with 120-grit sandpaper to create a seamless surface. Apply a very thin layer of lightweight paintable spackle over the filler with a putty knife, then sand again once dry.
8
Brush matching paint over the repaired area. Apply two to four very light coats, allowing each coat to dry completely before applying the next.
Pro Tips
Run your fingers over the surface after the final sanding to ensure it feels completely smooth before painting.