When cracks form in the floor of your shower, the openings in the shower base can lead to other issues. Due to the regular presence of water on the shower floor, rust or mildew may form in the openings. If you have minor cracks in your shower floor, you do not have to replace the entire floor. You can fill in a crack in your shower floor's surface, whether the surface is tile, fibreglass or porcelain, by using a waterproof filler.
Pick off any large flakes around the crack in the shower floor that feel loose. You can do this by putting on a heavy-duty glove and moving your covered finger back and forth over the surface of the crack to loosen the flakes naturally. Use a wet rag to remove the flakes from the surface once they're loose.
Mix epoxy resin with the provided hardener according to the instructions provided on the packaging. Combine the hardener with the resin right before you plan to use it. If it sits too long, it will harden in the bowl.
Spread the epoxy resin mixture over the crack in the shower floor with a putty knife. Once the crack is filled, turn the putty knife so that the edge sits against the surface of the shower floor at one edge of the filled crack and pull the knife across the crack to skim off excess resin.
Wipe the area around the crack immediately with a wet rag to remove epoxy left on the surface, and also wipe the epoxy off the putty knife immediately. Keep stirring the epoxy resin for about five minutes as the filled crack sets up.
Inspect the crack in the shower floor. If the epoxy sunk down, the crack may no longer be level with the surface of the floor. If this is the case, apply a second layer of epoxy to the crack, skim the excess caulk from the surface, and wipe the surrounding area and putty knife.
Wait until the second layer of epoxy dries and fill the hole again if it sinks again. Once the hole dries evenly, or slightly above, the surface of the shower floor, sand the epoxy carefully, trying to avoid the surrounding shower floor surface to minimise scratches. Sand the epoxy until it sits level with the floor.
When disposing of leftover epoxy mixture, just let the epoxy harden in the bowl and throw the entire bowl away. If the epoxied crack is noticeable in your shower floor, you can touch the spot up with paint in the same colour as your tiles, fibreglass or porcelain. Use a waterproof paint and go over the paint with waterproof sealant for the most lasting results.