How to Repair a Fiberglass Door

  • 24-48 hours
  • Intermediate
  • 100-300
What You'll Need
Fiberglass Patching Fabric
Fiberglass Mat
Razor Blade

Fiberglass doors are very strong. However, over time fiberglass can become scratched or damaged. Any cracks in fiberglass doors can be repaired using special compounds and solutions. When repairing a fiberglass door you will need to ensure that this is done properly so that the finish is completely smooth.

Repairing a fiberglass door is actually much easier than you might imagine. With the right products you should be able to easily repair any cracks in the doors regardless of their cause.

Step 1 - Locating the Damage

The first thing that you need to do is spend time looking for the damage caused to the fiberglass door. Sometimes the damage won't be clearly visible which will mean you need to spend time looking for it. Tapping the fiberglass with something hard will be able to help you identify damage, if there is a dull sound then this will be a damaged piece of fiberglass.

Step 2 - Cutting out the Damage

Now use your grinder to cut out the damaged area in the fiberglass door, use the grinder to cut at an angle so that you taper the size of the hole. This will be beneficial to help the new patches stick to.

Step 3 - Solvents

Clean the hole that you have just cut in the door by using solvent, this will get rid of any dirt and grime which could stop the bond being strong. By cleaning with solvents you are ensuring that the bond is as strong as possible.

Step 4 - Paste Wax

Paste wax needs to be placed around the hole, this will stop resin from bonding with the exterior of the door and making the door look unattractive.

Step 5 - Waxed Backer

A waxed backer can be taped or screwed inside the bottom of the hole. This is a stable surface to work from when you are patching and repairing the hole in the door. This should be a smooth finish which will match the rest of the fiberglass in your door.

Step 6 - Cutting the Fiberglass Fabric

Now measure the size of the hole and cut the right sized piece of fiberglass fabric and mat. Use two layers of the mat and then the fabric, you can then alternate between the different layers for the best result. You will need to use the right number of layers to fill the hole properly however you should avoid doing more than four layers where possible.

Step 7 - Resin

An epoxy resin now needs to be used to patch up the hole and this can then be used to secure the polyester fabric and mat securely. You will find it better to use laminating resin because this will make the bond much stronger.

WARNING: Epoxy products can release fumes, so make sure you read the resin's label and wear the recommended safety gear (such as a face mask and safety glasses). It's also usually a good idea to open any nearby windows to allow for proper ventilation.

Step 8 - Hardening Resins

Some epoxy resins will need another chemical which acts as a catalyst and harden the epoxy resin. If this is the case you will need to follow the directions of the manufacturer which will tell you exactly how much you need to use. A resin roller can then be used to remove any of the air bubbles in the resin.

Step 9 - Finishing Touches

The wax backer needs to be removed. If there are any imperfections then you can fill these using some more gelcoat. Sand the finish down until you create a seamless repair.

WARNING: If you use an electric sander for this step, wear safety glasses and a face mask to keep epoxy particles from getting into your eyes or lungs.