Fiberglass garage doors have the advantage of being both light and strong. They also have a fairly easy to maintain surface that only requires the occasional cleaning. However, the door can be damaged if you accidentally bump into it with your car. Depending on how extensive the damage is, it might be possible to repair it with a little work. When you're dealing with a big crack, it's probably best to simply replace the panel with a new one provided by the manufacturer. But for small cracks, you can use the following steps to repair the surface of the fiberglass.

What You Will Need

  • Water

  • Soap

  • Towel

  • Work Gloves

  • Sponge

  • 200 Grit Sandpaper

  • 300 Grit Sandpaper

  • Razor Blade

  • Kit for Repairing Fiberglass (Should Include Resin, Hardener, Scraper and Sheets of Fiberglass)

  • Paintbrush

  • Primer

  • Matching Paint

Step 1. Use a sponge and hot soapy water to thoroughly clean the damaged area of any dirt or grease. Then use a clean towel to completely dry the surface.

Step 2. Use 300 grit sandpaper to sand down any damage along the crack, such as raised edges or burrs. Any larger burrs can be cut off by carefully using a razor blade. Put on a pair of protective work gloves before you do this. You want to get the crack as smooth as possible.

Step 3. If the damage has resulted in an actual hole in the fiberglass, use the sandpaper to bevel the hole's edge. If there are any loose shards, cut them away with the razor blade.

Step 4. Take measurements of the damaged area and cut out fiberglass sheets to fit over the damage. This won't be necessary with small cracks, but larger holes or gaps that are bigger than 1 inch across will need the fiberglass sheets.

Step 5. For large holes or gaps, follow the instructions of the manufacturer and mix together the resin and hardener that came in the repair kit. Apply this mixture to the fiberglass sheets you cut out and layer the sheets over the damaged area. Wait 24 hours for the resin to completely harden. For smaller cracks, you can simply apply the resin directly to the crack. Smooth it out and allow it to dry for 24 hours.

Step 6. Use 200 grit sandpaper to sand the repair you made so it is smooth and even with the rest of the door. Use a clean towel to wipe away any dust.

Step 7. With a paintbrush, apply a coating of a fiberglass primer to the repaired area. Once this has dried, apply a paint color matching the current color of your garage door. Talk to a professional like Upstate Garage for more information.