How To Fix A Cracked Fiberglass Shower

Posted on: 6 November 2017

Fiberglass shower stalls commonly lasts a long time, since they can't bend against framing, but you may notice a crack or two in the finish during a bathroom remodel.

This likely occurred because of a dropped object. You don't need to buy a new shower stall, but you should repair it right away to keep water out of the frame. These steps will help you repair the crack

Prepare to Fix the Crack

To fix the stall crack, gather:

  • work gloves 
  • respirator or fan white distilled vinegar
  • sponge
  • fiberglass cloth
  • cellophane tape 
  • putty knife
  • 120-grit, 400-grit sandpaper
  • 240-grit wet/dry sandpaper
  • groove cutter
  • fiberglass repair kit
  • small paint brush 
  • touch-up paint (optional)

To determine if the tub is fiberglass, tap on it with you knuckles or a wooden object. Fiberglass makes a hollow, non-metallic sound. 

Mix a cup of white vinegar in a gallon of warm water, and wipe the stall surface to remove grime. Rinse, and let the stall dry

Widen the Crack

Raise a window and run a fan, or wear a respirator when working with fiberglass particles. You will need to widen a small to medium crack so the epoxy or filler can fit. 

Slightly pull the crack further using your hands, then make a V-groove to measure one and one-half inches with a file or groove cutter. Lay cellophane tape around the repair edges to avoid damaging the good surface. 

Mix the Filler

Set cardboard or poster board down on the surface where you mix the epoxy. Fiberglass kits and epoxy kits should come with a mixing container. 

Some kits will give a specific amount of resin to mix according to crack size. Mix the filler adding the suggested amount of resin, matching colorant, and hardener with the stirrer provided in the kit 

Compare the color against the surface to check color match. Quickly work it into the groove using the applicator provided or a small paint brush, pushing it down in the crack using a putty knife. 

Apply the Filler

To reinforce longer cracks, cut a nine-inch piece of fiberglass, spread epoxy on it, and lay two pieces of wet tape it over the surface. To correct errors, go over the surface with 240-wet/dry sandpaper. Let the material set 24 hours or for the suggested time, then sand using 400-grit sandpaper.

After the area dries, mix the polyester fiberglass filler in a matching color. Polyester fiberglass filler resembles auto body filler.

Add the hardener, and use a putty knife to spread it on the surface. Let it cure, then sand lightly with 120-grit sandpaper. Add touch up paint, if the color isn't an exact match.