How To Resize an Exterior Door

If your door doesn’t fit the frame, scrapes across your floor, or gets stuck on your carpet, you may need to resize it. This common issue can be caused by various factors, such as your home settling on the foundation or after installing a new floor. In the video above,This Old House expert contractor Tom Silva helps a homeowner resize a door that’s hitting a carpet, offering a clever solution without removing the entire door frame or destroying any of your existing trim. With the right tools and careful attention to detail, you can resize your own door to solve this issue.

Why Should You Resize Your Door?

You may need to resize your door for many reasons, most of which involve changes in your home’s structure or foundation.

• New flooring installation: When new flooring is installed, it can raise the floor level, causing the door to scrape or stick. 
• Home settling: Over time, houses settle, which can change how your door is aligned.
• Incorrect installation: Sometimes, doors are hung too low during the original installation without considering the height of the floor. Silva notes that in this house, “When they originally hung the whole front door, they hung it into the opening a little bit too low. They didn’t allow for any carpet or rug here.”

Before resizing the door, measure the gap between the door and the floor, and check if the door is level to determine how much material you should remove from the bottom of the door. 

Preparing for Resizing your Exterior Door

Follow the steps below to make sure you’re prepared for your project. Always take care when working with power tools, and have someone help you with moving the door if possible.

Pro Tip: Before you begin, measure the width of your door opening, jamb to jamb, in three places — top, middle, and bottom—and the height, threshold to jamb, in three places. Note the largest measurement of each and use these as your guide. Doors come in standard sizes, the most common being 80 inches high and 30 inches wide. Keep in mind that most solid-core doors can’t be trimmed more than an inch before they show their core, so if your door size isn’t close to standard, you may need to custom order or buy a solid wood door.

Tools and Materials Needed

• Tape measure
• Hammer
• Pencil
• Track saw or circular saw with a track
• Block plane
• Paintbrush
• Table saw
• Power grinder
• Chisel
• Brad nailer
• Wood glue
• Oil-based primer
• Sandpaper or sanding block (various grits)
• Red oak board (for threshold filler)
• Stain (matching the threshold color)

Pro Tip: Subtract 1/4 inch from the width and height of your door opening to determine the final door size—this leaves a 1/8-inch gap between the door and the jamb on all sides. If the amount to be trimmed is less than 1/8 inch, you can plane it down; more than that and you’ll need to use a circular saw. If you need to trim the height, always take from the bottom of the door, where the thicker rail is. To trim the width, take evenly from both sides.

Safety Precautions

When working with power tools, wear protective eyewear, gloves, and a dust mask. Keep your work area well-ventilated, especially when applying primer or stain. Be sure you have enough lighting to see all aspects of the work.

Step-by-Step Door Resizing Process

Here, we’ll walk you through each step of resizing your door. Pay careful attention to your work so that it is accurate and you don’t damage your door.

1. Take the door off of its hinges and put it on a stable work surface or door stand.
2. Measure and mark the amount you need to cut from the bottom of the door, about ¼ inch. For larger adjustments, keep the cuts consistent along the bottom edge.
3. Using a track saw or circular saw with a track, cut along the marked line. With a track saw, you’ll need to push down as you move across the width of the door. The track helps you cut straighter and protects the door’s finish. For thicker doors, you may need multiple passes with the saw
4. Sand the cut edge of the door to smooth any roughness. Start with coarser grit sandpaper and move to finer grit for a smooth finish.
5. Use a block plane to slightly ease the edges of the cut and prevent splintering. This step is important for avoiding small cracks or splits in the wood.
6. Apply oil-based primer to the raw wood at the bottom of the door to protect it from moisture. Allow the primer to dry completely before proceeding.
7. Rehang the door on its hinges and check the fit, ensuring it’s even on both sides. Make any necessary adjustments so that the door swings freely and does not scrape against the floor.

Pro Tip: Before cutting your door with a circular saw, roll out painter’s tape along the cut line. Mark your line on the tape and score it with a utility knife—this keeps the saw blade from chipping the wood as it cuts through. With the saw braced on a cutting guide and its blade on the waste side of the line, slowly trim the door.

Create an Exterior Threshold Filler

After resizing the door, you’ll likely have a gap between the door’s bottom and the threshold, so here’s how to fix it:

1. Measure the gap between the door and the threshold on both sides.
2. Cut a piece of red oak to fit this gap using a table saw. The cut piece’s thickness needs to match the gap measurements.
3. Grind off any finish on the old threshold with a power grinder to create a smooth surface that the glue will stick to better.
4. Use a chisel to clean varnish from corners where the grinder can’t reach.
5. Test-fit the filler piece and mark where the door’s edge meets it. 
6. Cut a bevel on the inside edge of the filler piece using a table saw. 
7. Stain the filler piece to match the existing threshold and allow it to dry. 
8. Secure the filler piece to the threshold using wood glue and headless brad nails, applying consistent pressure for a strong bond.

Door Resizing Finishing Touches

Put a professional polish on your door with the following techniques:

1. Check the door’s operation. It should swing freely without hitting the floor or threshold. If it’s scraping, make hinge or fit adjustments.
2. Adjust the weatherstripping as necessary to keep out drafts and improve your home’s energy efficiency.
3. Keep extra paint or stain so you can touch up the door and protect the wood surface. Make sure you stain or paint the door before the installation for full coverage.

Troubleshooting Common Exterior Door Resizing Issues

No matter how carefully you resize your door, you may run into some roadblocks. Here are some common problems and their simple solutions:

• Uneven cuts: If your cut isn’t perfectly straight, use a belt sander to even it out. Work carefully to get a level bottom edge. Use a leveling tool to check that it’s straight.
• Door still sticks: If the door still sticks after resizing, your hinges may be loose or worn. Adjust or repair the hinges where you can, and if they’re damaged, replace them to avoid further alignment issues.
• Gap is too large: If you’ve cut too much off the door, creating a large gap, you may need to add a door sweep to cover the space and prevent drafts. Door sweeps come in many different styles and materials, so you have lots of options to fit your needs.
• Too much noise: If your door squeaks or creaks when you open or close it, apply a small amount of lubricant on the hinges. 

Taking Care of Your Resized Door

To keep your newly resized door looking nice and working properly without damaging your floor, follow these tips:

• Regularly check the threshold filler for signs of wear or separation and fix it immediately.
• Apply a fresh coat of sealant or paint to the door’s bottom edge to protect it from moisture. Do this regularly in areas with high humidity or frequent rain.
• Lubricate the hinges annually to prevent squeaking and sticking.
• Check the door alignment often, especially if the house continues to settle. You can usually make minor adjustments to your door again or take other smaller measures to keep the door swinging smoothly. 

Pro Tip: This Old House general contractor Tom Silva advises that a resized exterior door must be protected with a finish no matter what: “You’re gonna have to seal it in some way. You’re either gonna have to oil it, you’re gonna have to stain it, or you’re gonna have to paint it, but you’re gonna have to do something.” Leaving a freshly cut edge unfinished invites moisture damage and warping over time.