How To Install a Fiberglass Entry Door

Upgrading your home’s entryway with a new fiberglass door can improve its energy efficiency and curb appeal. These durable, low-maintenance doors offer the look of wood without the associated upkeep.

In this guide, we’ll show you how to install a fiberglass entry door, from removing the old door to securing the new one in place. In the video, This Old House general contractor Tom Silva demonstrates the key steps for a successful installation.

*Cost information in this article sourced estimates used by Angi.

Preparing for Fiberglass Door Installation

Gather the following tools and materials before anything else:

Tools and Materials Needed

• 3-inch weather-resistant screws
• 4-foot level
• Adhesive-backed waterproofing membrane
• Caulk gun
• Circular saw
• Drill/driver
• Fiberglass entry door (pre-hung)
• Flat pry bar
• Minimal-expanding spray foam insulation
• Reciprocating saw
• Scribe tool
• Shims
• Silicone adhesive

Removing the Old Entry Door

Removing the existing door is the first step in the installation process. Here’s how to do it safely and efficiently:

1. Use a reciprocating saw to cut through the nails between the doorjamb and wall framing.
2. Cut around the interior of the doorjamb to free it from the wall opening.
3. Pry the old door and threshold from the opening using a flat pry bar.

Preparing the Door Opening

Leveling and adequately prepping the door opening is crucial for a successful fiberglass door installation. This section covers the steps to ensure your door opening is ready for the new door.

Level the Subfloor

1. Cut a 2×4 to span the doorway opening and lay it on edge along the rough sill.
2. Place a level on top of the 2×4 and use shims underneath to achieve a level surface.
3. Measure down ½ inch from the top edge of the level 2×4 and mark a line.

Create Filler Strips

1. Adjust a scribe tool to span from the rough sill to the ½-inch mark.
2. Guide the scribe along the sill to draw a line on the 2×4.
3. Cut along the scribed line with a circular saw to produce a perfect-thickness filler strip.
4. Repeat the process to create a second filler strip.
5. Set the filler strips onto the rough sill and check for level.
6. Fasten the filler strips to the rough sill using 2-inch (6d) common nails.

Waterproof the Opening

1. Apply strips of adhesive-backed waterproofing membrane to the exterior wall area around the doorsill.
2. Run a thick bead of silicone adhesive along the ends and length of the rough sill.

Installing the Fiberglass Door

With the opening prepared, it’s time to install the new fiberglass door. This process requires precision and attention to detail to ensure proper fit and function.

Position the Door

1. Temporarily screw two 1×4 cleats across the frame of the new fiberglass door, extending at least 3 inches past each side.
2. Set the pre-hung door onto the rough sill, then tilt it flat and flush against the wall.
3. Center the door in the opening, aiming for about ¾ inch of space on each side.

Leveling and Plumbing

1. Check the threshold for level using a 4-foot level. If necessary, add shims under the threshold.
2. Use the level to check the hinge-side doorjamb for plumb.
3. Insert shims between the doorframe and wall framing as needed to achieve plumb.

Secure the Door

1. Once the hinge-side jamb is plumb, drive 3-inch weather-resistant screws through the jamb and shims into the wall framing at the top, middle, and bottom.
2. Secure the upper door hinge with the two long screws provided by the door manufacturer.
3. Screw the latch-side jamb to the wall framing, ensuring it’s plumb.

Finishing Touches

1. Install the deadbolt and lockset onto the door according to the manufacturer’s instructions.
2. Fill the space between the doorframe and wall framing with minimal-expanding spray foam insulation.
3. Open and close the door several times to ensure it swings freely and latches securely.

Benefits of Fiberglass Entry Doors

Fiberglass entry doors offer numerous advantages over traditional wood or steel doors. Let’s review the perks in detail.

Energy Efficiency

Fiberglass doors are excellent insulators, helping to maintain a comfortable indoor temperature and potentially reducing energy costs. The foam core mentioned by Tom in the video contributes significantly to the door’s insulating properties.

Durability and Low Maintenance

Unlike wood doors, fiberglass doors resist warping, rotting, and cracking. They don’t require frequent painting or staining, making them a low-maintenance option for busy homeowners.

Aesthetic Appeal

Modern fiberglass doors can closely mimic the appearance of wood, complete with realistic grain patterns. They’re available in various styles and colors to complement any home’s exterior.

Additional Tips for a Successful Installation

To ensure that your fiberglass door installation goes as smoothly as possible, here are a few more tips and considerations to keep in mind:

Checking Alignment

1. After securing the door, double-check for proper alignment with the door frame.
2. Make any necessary adjustments to the shims or screws to ensure the door sits squarely in the opening.

Weatherproofing the Door

1. Add additional weatherstripping around the door to prevent drafts and increase energy efficiency.
2. Make sure the weatherstripping compresses tightly when the door is closed.

Painting or Staining

Though fiberglass doors require less maintenance than wood, you can still paint them to match your home’s exterior. Use high-quality exterior paints or stains designed for fiberglass to ensure a long-lasting finish.

Hardware Installation

If installing new hardware, confirm that you’ve lined it up correctly and test it for smooth operation. This check may involve adjusting the strike plate in the jamb or fine-tuning the alignment of the deadbolt and latch.

Final Inspection

Once the installation is complete, inspect the door’s operation. It should open and close smoothly without sticking, and all locks should function correctly. Make any last-minute adjustments as needed.

Tools