How Can I Fix a Crack in the Fiberglass Floor of My Shower With Epoxy?

Clean your shower and dry it thoroughly to identify the full length of the crack and possibly discover others.

Drill a small hole at each end of the crack, using a ¼-inch drill bit or smaller. Spray insulating foam into each of the holes to form an airtight seal and prevent the crack from leaking water into the flooring beneath.

Widen the crack in the fiberglass, using a disk sander attachment on your drill or an angle grinder. Use 36- to 40-grit abrasive for this task. When you finish, the crack should be 12 times wider than the thickness of your fiberglass laminate. If you don't know the thickness of your fiberglass laminate, widen the crack just enough to allow you access to the deepest part of the crack.

Cut a strips of fiberglass cloth the width of the crack. Coat the cloth in epoxy and mold the cloth into the crack. Repeat the process with progressively smaller strips of epoxy-coated fiberglass cloth until the crack is patched. Let the fiberglass cloth dry overnight.

Touch the fiberglass cloth to ensure it's completely dry, then sand the fiberglass and epoxy filler into the surrounding shower surface with 80-grit sandpaper. Continue sanding until the filled crack is smooth. Clean the area with a damp cloth.

Paint the repaired crack with epoxy gel coat approximately the same shade as your shower’s surface. Allow the gel coat to dry for 24 hours, then sand smooth with 400-grit sandpaper.