How to Refinish a Fiberglass Exterior Door (Step-by-Step)

alt="Refinished red fiberglass exterior door with protective finish" — It’s amazing how much services such as refinishing a door can cost. As fewer people are willing to take on dirty, skilled work, the economics of doing it yourself improve.

Video Watch Time = 7 1/4 minutes

Refinishing a fiberglass exterior door (and wood ones, too) is a job many homeowners assume requires a professional. In reality, it’s a manageable DIY project if you understand the key differences between fiberglass and wood. With the right stripper, stain and sealer, you can restore a weathered door and save hundreds of dollars.

Key Takeaways

• Fiberglass exterior doors can be stripped and refinished by homeowners just like wood.
• Use gentle scraping instead of aggressive sanding.
• Citrus-based paint strippers work well and are safer for fiberglass.
• Gel stains create an even finish on non-absorbent fiberglass.
• Seal the door with exterior spar varnish for long-term protection.

Can You Refinish a Fiberglass Exterior Door Yourself?

Question: Is it reasonable for me to strip and refinish the fiberglass exterior doors at my house? They face south and the old finish is in bad shape. I’ve been quoted $1000 to do this job (just refinishing, not even door replacement!), but I can’t afford it.

Answer: That’s a pretty big number for refinishing, but the good news is that stripping and refinishing is definitely something you can do yourself. The process is similar to working with a wood door, but with key differences you should know about.

How to Strip and Refinish a Fiberglass Exterior Door

The main difference compared with wood is that stripping fiberglass involves more gentle scraping and brushing and less sanding. Start work by removing the door and all hardware. You need to have your doors horizontal for best results. Don’t even attempt to refinish the door in place. When I’ve done work like this I cut a piece of plywood to cover the door opening, with a rope pushed through a couple of holes in the door and tied to a stick of wood that spans the opening at the back. The process of stripping and refinishing will take some time too, so you really will need to rig something up on your doorway if you don’t have a screen door or a retractable screen door to keep bugs out and maintain some ventilation.

Apply a mild paint stripper to a small, inconspicuous place to make sure that it doesn’t hurt the fiberglass. There will probably be no issues, but the stakes are high so proceed with caution. A product called Citristrip is a citrus-based paint stripper that should not harm your door. Test to make sure.

Apply the stripper, let it sit for 20 minutes, then use a plastic scraper (not metal) to peel off as much of the old finish as possible. If your door has nooks and crannies from various decorative panels that may be part of the design, use a toothbrush to remove the old finish in close quarters. You’ll probably have to apply, scrape and brush at least twice. Perhaps even three or four times. When the old finish is completely gone, use a shop vac or leaf blower to remove all remaining dust, then apply a gel stain with a foam brush. Since fiberglass isn’t absorbent like wood, you’ll need to be careful to apply an even coat of stain. Let the stain dry for a couple of days, then apply two coats of exterior sealer. Helmsman spar varnish in the satin formulation has worked well for me.

Spar varnish is a clear, film-forming sealer that works as well on fiberglass exterior doors as it does on wood. It’s applied over top of any kind of gel stain on to the fiberglass.

Alternative Option: Painting a Fiberglass Exterior Door

In the photo above I’m applying it to wood, but it works just as well on fiberglass. As an alternative you could also apply spray paint to your door if you want a solid colour. The best spray paint for large areas that I’ve used is Rust-Oleum’s Turbo version. It comes in big cans and delivers a wide spray pattern. You can see it in action in the video below.

This video demonstrates surface preparation and spray application techniques that also apply when painting a fiberglass exterior door.

Frequently Asked Questions

Can you refinish a fiberglass exterior door?

Yes. Fiberglass exterior doors can be stripped and refinished using gentle scraping, gel stain and a protective exterior sealer.

Do you need to sand a fiberglass door before refinishing?

Usually only lightly. Most of the old finish should be removed using paint stripper and a plastic scraper rather than heavy sanding.

What stain works best on fiberglass doors?

Gel stain works best because fiberglass does not absorb stain the way wood does, making it easier to control colour and achieve an even finish.

What clear finish should be used on a fiberglass exterior door?

Exterior spar varnish works well because it forms a durable weather-resistant film that protects the door from sun and moisture.

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