Door Sanding

Do You Need To Sand a Fiberglass Door Before Painting?

In Remodeling by Giovanni ValleLeave a Comment

Fiberglass doors are a popular choice for homeowners due to their durability and low maintenance requirements. If you want to give your fiberglass door a new coat of paint, you may wonder if you should sand it first or if the process is entirely unnecessary.

You do not necessarily need to sand your fiberglass door before painting it. However, sanding a fiberglass door helps remove minor imperfections and ensures the paint adheres more effectively. Your painted door will have a smooth, even finish once dry.

This article covers the steps to prepare a fiberglass door for painting. Don’t worry if you’re feeling overwhelmed; I’ll walk you through each step in detail.

How To Prepare a Fiberglass Door for Painting

Painting a fiberglass door can give it a fresh new look and update the appearance of your home. However, before you can begin, it’s essential to prepare your door for the painting process as follows:

1. Remove All Door Hardware

Before anything else, remove the doorknob, deadbolt, and other hardware attached to the door. This is important because it will ensure that the paint covers all areas of the door, including the parts around the hardware. To remove these components, use a screwdriver.

2. Clear the Door of Weatherstripping

Weatherstripping is a standard feature on fiberglass doors to seal the door and prevent drafts. However, painting over weatherstripping can cause it to deteriorate quickly and lead to air leaks. Use a putty knife to pry the weatherstripping off the door.

3. Remove the Door from the Hinges

Removing the door from the hinges will make it easier to paint the door, as you can lay it flat on a surface and paint all sides at once. It will also ensure that you can paint all over the critical parts of the door. Use a screwdriver to remove the screws holding the door in place and carefully lift it off its hinges.

4. Place a Painter’s Tarp or Drop Cloth Along the Door

You’ll also want to protect the surrounding area from drips and spills. One way to do this is by placing a painter’s tarp or drop cloth along the floor and on any surrounding surfaces that drips could affect. You can also use old newspapers if you use several layers to prevent the paint from leaking through them.

5. Wipe the Door With Acetone or Other Mineral Spirits

Dirt, dust, and grease can all interfere with the adhesion of paint, so it’s essential to ensure that your door is as clean as possible before you begin painting. Using a cloth saturated with acetone or other mineral spirits, wipe down all surfaces of the door and allow it to dry thoroughly before going to the next step.

6. Wash the Door With a Mild Detergent Solution

Once the door is free of dust, dirt, and grease, you can wash it with a mild detergent solution to remove any residue that may have been left behind by the acetone or mineral spirits. Use a cloth or sponge soaked in warm, soapy water and gently scrub the door. Rinse the door with clean water once you’re done, and allow it to dry thoroughly.

7. Sand Down the Wooden Trim

Sanding down the wooden trim on the door can help the paint adhere better to the wood, providing a more even finish once the paint is applied. Also, if the trim is bumpy or uneven, sanding it down can smoothen it.

Use fine-grit sandpaper and carefully sand the trim in a circular motion to remove any rough spots or imperfections on the wood. Then, use a lint-free cloth dipped in acetone to remove any dust or debris that may have been created during the sanding process.

8. Use Painter’s Tape to Mask the Glass

You need to mask off the glass on the door to prevent paint from accidentally getting onto it. Use painter’s tape to cover the edges of the glass, and ensure that the tape is securely applied and that there are no gaps or openings.

This will help keep the glass free of paint during the painting process. Additionally, if you keep the existing hardware on the door, you need to cover them with painter’s tape to ensure the paint doesn’t damage the hardware.

9. Prime the Sanded Wooden Trim

Applying a primer to the sanded wooden trim is vital to ensure the paint adheres properly to the wood. Primers are specifically designed for use on bare wood and help create a more even finish once the paint has been applied. Use a brush or roller to apply a coat of primer to the trim, and allow it to dry completely before continuing with the painting process.

Tips When Sanding a Fiberglass Door

  • Use the correct type of sandpaper. Use fine-grit sandpaper (150-220 grit) to prevent damage to the door and ensure a smooth finish.
  • Sand with the grain, not against it. This helps to avoid damaging the door and to create a smooth, even surface for the paint to adhere to.
  • Use a sanding block. A sanding block will help evenly distribute the pressure you apply when sanding.
  • Wear a dust mask. Sanding generates a lot of dust, so wearing a dust mask is vital to protect your lungs.


Sanding a fiberglass door before painting ensures that the paint adheres properly and provides a more even finish. Follow the steps outlined above and take all necessary safety precautions when sanding a fiberglass door to ensure the job is done correctly. With a little effort and patience, you can give your door a beautiful new coat of paint without worrying about imperfections or unevenness.


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