How to Repair Rotted Window Frames and Make Them Look Brand New

Having to repair rotted window frames isn’t necessarily a fun task. After all, windows are an essential part of your home’s framework, adding some visual pizazz to both the exterior and interior. When something is wrong with the windows, you can really feel it in your home. 

Unfortunately, the wood surrounding these glorious windows to the outside world is susceptible to various types of rot. Don’t fret. You (probably) won’t have to toss the window and start over, though hiring a local carpentry expert for an assessment is always a good idea. Depending on the severity, there are also DIY solutions to give your windows the structural stability they deserve.

Keep reading to learn how to repair rotted window frames in two different ways.

Use Epoxy Wood Filler

For minor instances of wood rot, patch it up with a wood filler epoxy. This involves removing the rotted material, cleaning out the gap, and then filling that gap with the epoxy substance. Wood fillers work well here, becoming indistinguishable from pre-existing wood once sanded and painted. 

1. Gauge the Severity

Wood filler only works when the rot has permeated less than 2 inches into the wood. Push into the rot with a putty knife or screwdriver to see how far the rot extends.

2. Create a Gap

Remove all of the infected wood with a large putty knife, a gloved hand, a hammer, or a construction chisel. Clean up the wood until a large gap forms.

3. Fill the Gap

Mix your preferred wood filler according to the manufacturer’s instructions. Next, use a putty knife or scoop to apply the epoxy into the gap. 

4. Cure, Sand, and Paint

Allow the epoxy to dry and cure according to the instructions. Then, sand and paint the area until it matches the rest of the frame.

Create a Wood Insert

If the rot extends beyond one or 2 inches, the damage is likely too severe for a simple wood filler. In these cases, replace the rotted wood around the window with a custom wood insert.

This is an involved repair procedure, requiring a fair bit of supplies and some knowledge of basic carpentry skills. If you are unsure of your skill level here, call in a pro.

1. Remove the Rot

The first step is removing the rot itself from the frame. Use a pry bar or a combination of hammer and chisel to extract the rotted pieces from the rest of the window. Try to work the pry bar behind the rotted wood to remove it all at once. 

2. Clear a Gap

Make sure the gap is completely clear, removing any nails, additional wood, or items of debris. Lay down some flashing tape for additional protection against future water damage.

3. Measure the Rotted Wood

Take the pieces of rotted wood you removed and arrange them so they fit together. Measure the dimensions of these pieces. If you get lucky, the measurement will correspond to standard lumber sizes.

4. Purchase Wood and Cut Down to Size 

Purchase the closest approximation to your measurement and cut the wood down to an exact fit using a circular saw. Test it out by placing the shaped wood inside of the gap.

5. Paint, Prime, and Fasten

Place the wooden insert in the gap and add some primer and paint to match the rest of the frame. Finally, fasten the wood insert with exterior-grade construction screws. 

6. Caulk and Paint the Seams

Use a caulking gun to fill in any gaps. Allow ample time for the caulk to dry completely (check the manufacturer’s instructions for more specific guidance), and then paint the seams.

When to Replace the Window Frame Entirely

Of course, some instances of wood rot are simply too severe to repair using either of the above methods. In these cases, replace the entire window frame. If the rot not only extends beyond 1 or 2 inches deep but also surrounds the entire frame, your best bet is a full frame replacement. 

Window replacement costs are higher than repairs, but on the upside, replacing the window frame from the ground up allows contractors to choose sturdy wood and seal it effectively to minimize any future risk of rot.

DIY vs. Hiring a Pro

Repairing a rotted wood frame can be a budget-friendly project. A good epoxy wood filler typically costs between $10 and $50. If you already have caulking guns, circular saws, and pry bars, the cost is limited to the filler and any additional materials you need, like paint and primer. Creating a custom wood insert, if required, can cost as little as $10 to $50, depending on the type and amount of lumber needed.

Undertaking the repair yourself allows you to have full control over the process and potentially save money on labor costs. However, keep in mind that DIY repairs require time, effort, and attention to detail. Without sufficient expertise, there’s a chance of making mistakes or not achieving the desired results.

If you choose to go pro with this one, carpenters with your local window repair company typically charge between $30 and $100 per hour, depending on their experience and location. Hiring a pro ensures that the job is done efficiently and to a high standard.

Lawrence Bonk contributed to this piece.