How To Patch Wood

Repairing damaged or rotted wood is a valuable skill for any homeowner. Whether you’re dealing with a worn door frame, a weathered windowsill, or a deteriorating piece of trim, knowing how to patch wood can save you time and money. In this guide, we’ll walk you through the process of making an undetectable repair in rotted wood, using techniques demonstrated by This Old House general contractor Tom Silva.

*Unless otherwise noted, costs in this article reflect an average of prices that our team found from hardware stores like Lowes and Home Depot, and on Amazon.com.

Understanding Wood Patching

Wood patching is the process of repairing damaged or decayed areas of wood by removing the affected portion and replacing it with a new piece. This technique is particularly useful for addressing localized damage without replacing the entire wood component.

When To Patch Wood

Patching wood is appropriate in several scenarios:

• Cosmetic damage from impacts or wear
• Filling holes left by removed hardware
• Repairing split or cracked wood
• Small areas of rot or decay

Benefits of Wood Patching

There are several advantages to patching wood rather than replacing the entire piece:

• Allows for targeted repairs
• Can be completed relatively quickly
• Cost-effective solution
• Maintains structural integrity
• Preserves original woodwork

Tools and Materials Needed for Wood Patching

Before beginning your wood patching project, gather the following tools and materials:

• Carpenter’s glue
• Chisel
• End nippers
• Hammer
• Layout square
• Miter box
• Nailset
• Poplar wood (or wood matching the original)
• Primer and paint
• Random orbit sander
• Router
• Router guide bushing
• Sandpaper (100-grit)
• Tape measure
• Utility knife
• Wood putty
• 1 1/2-inch finishing nails
• 1×3 boards for router guides

Prepare the Damaged Wood Area

The first step in patching wood is to properly prepare the damaged area. This ensures a clean surface for the new patch to adhere to and creates a precise fit.

Remove Nails and Screws

Begin by carefully removing any nails or screws from the damaged wood area. Use end nippers to extract these fasteners, ensuring you don’t cause additional damage to the surrounding wood.

Set Up Router Guides

To create a clean, straight edge for your patch, nail 1×3 boards around the damaged area. These boards will act as fences to guide your router, ensuring accurate cuts.

Route the Damaged Wood

Using a router is an efficient way to remove the damaged wood and create a clean recess for your patch. Tom demonstrates this technique using a router equipped with a straight bit and guide bushing. This creates a smoother and more precise result than attempting to chisel the area freehand.

Router Setup

1. Attach a straight-cutting router bit to your router.
2. Install a guide bushing to follow the 1×3 fences.
3. Set the depth of the router to match the thickness of your patch material.

Routing Process

1. Hold the guide bushing against the 1×3 fences to ensure straight, accurate cuts.
2. Slowly move the router across the damaged area, removing the old wood.
3. Make multiple passes if necessary to achieve the desired depth.

Prepare the Wood Patch

Creating a well-fitting patch is necessary for an undetectable repair. Follow these steps to prepare your patch material.

Select the Right Wood

Choose a piece of wood that matches the original as closely as possible in terms of grain, color, and texture. Poplar is often a good choice for painted surfaces due to its smooth grain and ability to take paint well.

Cut the Patch

1. Measure the routed recess carefully.
2. Mark your patch material to match these dimensions.
3. Use a miter box and backsaw to cut the patch to size.

Create a Two-Piece Patch

If you’re repairing an area with multiple wood components, such as a door jamb and casing, create a two-piece patch to match the original construction.

1. Measure and mark the division between the two pieces.
2. Use a utility knife and straight edge to score and separate the patch into two pieces.

Install the Wood Patch

With your patch prepared, it’s time to install it in the routed recess. This process requires precision and patience to ensure a seamless repair.

Apply Adhesive

1. Spread a thin, even layer of carpenter’s glue on the back of the patch.
2. Avoid using too much glue, as excess can squeeze out and make cleanup difficult.

Secure the Patch

1. Carefully place the patch into the routed recess.
2. Use 1 1/2-inch finishing nails to secure the patch in place.
3. Set the nails slightly below the surface using a nailset.

Fill Nail Holes

Once the patch is secured:

1. Fill the nail holes with wood putty.
2. Allow the putty to dry completely before proceeding to the next step.

Finishing the Wood Repair

The final steps in the wood patching process involve sanding and painting to create a seamless blend with the surrounding wood.

Sand the Patch

1. Once the wood putty has dried, sand the patch smooth using a random orbit sander fitted with 100-grit abrasive.
2. Pay special attention to the edges where the patch meets the original wood, ensuring a flush transition.

Paint the Repaired Area

To complete the repair:

1. Apply one coat of primer to the patched area and surrounding wood.
2. Once the primer has dried, apply two topcoats of paint to match the existing finish.
3. Feather the edges of the paint to blend seamlessly with the surrounding area.

Final Touches

After the paint has dried, inspect the patched area. If any imperfections are noticeable, lightly sand and apply another touch-up coat of paint. This will ensure that the repair is virtually invisible, maintaining the aesthetic appeal of your woodwork.

Maintenance Tips

To prolong the life of your wood and prevent future damage, consider these maintenance tips:

• Regularly check for signs of wear or rot and address them promptly.
• Apply a protective finish to exposed wood surfaces, such as varnish or paint, to shield them from moisture.
• Keep an eye on caulking around windows and doors, as deteriorated caulking can allow water ingress.

Tools You’ll Need