How to Paint a Fiberglass Exterior Door

A fiberglass exterior door can last a lifetime and save you money in the long run. But if you’re not careful, it could end up costing more than you bargained for.

How to Paint a Fiberglass Exterior Door

This blog post will cover topics on how to paint a fiberglass exterior door and go over everything from preparing your door to choosing the right paint and brush to install your new door is easy as possible. When you are looking for a new door for your home, there are many things to consider. One of the most important things to think about is what kind of door you want.

What Are The Things You’ll Need to Paint a Fiberglass Exterior Door?

First and foremost, you’ll need to gather all the tools that you’ll need to paint a fiberglass exterior door. Then, of course, you’ll need your fiberglass door itself. But there are other things that you’ll also need before you get started on painting it as well.

Here’s a list of supplies that will make your job easier:

•  Drill Screwdriver

•  Jigsaw

•  Hacksaw

•  Sandpaper (120, 180, and 220 grits)

•  A pair of safety glasses

Step by Step Guide: How to Paint a Fiberglass Exterior Door

If you have access to a paint shop, then your step-by-step process should be as follows:

Step 1:

Clean the fiberglass door with mineral spirits or an ammonia, bleach, and water solution.  This will ensure that there is nothing on the surface of the door that can compromise your hard work in painting it. Next, give your door a light sanding.  Try to get all the surface imperfections off of it you can, but don’t overdo it. If you want to change the color of your door, you will need to use a primer designed for fiberglass. This will help the new paint to adhere to the door and will also provide a good base for the new color.

Step 2:

Mask the area around your door. If you have never used tape before, feel free to practice this step on another part of your house just in case issues with how you apply the tape or if you need to buy a different kind. If you have never done this before, I would recommend using the painters tape rather than the masking tape.

Mask the Area  Around Your Door

Step 3:  

Paint your door with primer. Then, apply two coats of paint on top of that. The most important part about this step is to get good coverage while making sure you are not using too much paint so it dries before it can be smoothed out. Take your time and make sure you get it just as good as you can with a brush. Then, use a small roller on the door to smooth out any brush strokes.

Step 4:  

Once the paint is completely dried, you will sand down all of the rough spots left by your paint job. After that, apply one last coat of paint to fill in any places that still need smoothing out. This may require more than one coat of paint.

Step 5:  

Once again, apply a few thin coats of your top-coat color to get smooth coverage and to avoid getting too much paint on the surface and causing bubbles that would need sanding out later. If you want your door to look good, I suggest this step be done carefully.  While the topcoat is still wet, you will have a large amount of opportunity to make it look the way you want, but if you leave too much on, you may not be able to get that part smooth enough without sanding and re-painting.

Step 6:  

Let your door dry! This is probably the most important step. You need to let the paint on your door dry for at least a week before touching it with anything but soft things like cloth. This gives the paint time to cure and make sure there aren’t any problems due to humidity or other factors.

Step 7:  

After your door has dried, you can peel off the tape and cleaner up the edges with either an edging tool or sandpaper and a nail buffer.

Step 8:  

Replace and install your door the same way you took it off. If you have a person helping you, have one of you hold the door up while the other puts in the new screws, but make sure to seal around them with caulking afterward.

Replace and Install Your Door

8 Tips To Make Your Fiberglass Door Paint Last longer:

1. Prepare the surface by cleaning it with a solution of household ammonia and water in equal parts. Rinse the door well to remove all traces of cleaner.

2. Use paint that is specifically made for fiberglass, vinyl, and aluminum surfaces. Do not use paints intended for wood or metal on fiberglass.

3. Apply two coats of primer before painting the door. If you desire extra protection, apply a coat of non-yellowing clear sealer.

4. Use a paint that has been formulated for both outdoor and indoor use. It is important to note that some paints can only be used in one type of environment.

5. Paint small areas at a time (i.e., no more than 4-5 feet high). Allow the paint to dry between coats.

6. Apply at least two, but preferably three or four light, even coats of color. Avoid letting it puddle on the surface as it dries; this will cause lap marks later in your project. These small brush strokes are normal and can be easily sanded off.

7. Avoid using a roller in tight areas; use small brushes instead. If you decide to use a roller, be sure and place your door on sawhorses and not directly on the ground.

8. Use a quality brush designed for outdoor paint only (i.e.. NOT a house-painting brush). Do not allow the paint to puddle in the bristles as you brush; this can cause streaking and leave brush strokes on your project.

Precautions When Painting a Fiberglass Exterior Door:

  • Protect the surface from rain and sunlight during the painting process, or paint will fail to adhere properly.
  • Working on a door that is not in good condition can lead to delamination, chipping, etc. Any damaged areas must be repaired before painting takes place. Repair any dings/dents with a fiberglass mat and resin.
  • When sanding, use a large diameter paper to avoid scratching the fiberglass surface in any way. Also, pay extra attention to corners and edges when sanding. These are areas that can catch dirt/dust if worked on without care.
Use a Large Diameter Paper
  • Use a primer-sealer for the best adhesion of paint to the door. Primers are available in flat, semi-gloss, and gloss finishes depending on your preference.
  • For smoothest finish possible use an HP (high-pressure) spray gun rather than a standard air compressor type gun. Use a lightweight paint if using an airbrush or conventional sprayer to avoid sags and runs.

Frequently Asked Questions:

Q: Do I Need to Sand Fiberglass Door Before Painting?

A: Yes, it is a good idea to sand the fiberglass door lightly before applying primer and paint. Fiberglass tends to create slippery paint jobs, so using 80 grit sandpaper will help with the adhesion of the topcoat. Roughing up the surface of fiberglass also reduces shrinkage cracking when you apply primer and paints.

Fiberglass will still shrink a bit, just not as much. It is also good practice to sand any glossy finish off of the fiberglass door. A simple method for sanding down fiberglass is to use your hand and rub it up and down with some coarse grit paper attached. You can even buy cheap sanding gloves from hardware stores to save your hands from getting sore.


The process of painting a fiberglass exterior door can be daunting for some people, but if you follow the steps we have outlined in this blog post and take your time to really get it right, then you should end up with something that will last.

We hope all our hard work has helped make this task of how to paint a fiberglass exterior door seem less intimidating! However, if you are still worried about tackling such a project yourself, don’t worry! You can always contact us during the process or after completion; our team is here to help. Thank you for reading!

You may read also – How to Install Door Trim Without Nail Gun

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