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How to Repair a Rotted Window Frame

Updated: Mar 29, 2023

Tools and Materials Needed

Before starting any repair work, it is important to gather the right tools and materials. For this repair, you will need the following: a hammer, a screwdriver, a utility knife, wood putty, and paint or stain. You may also need a chisel and a saw if the rot is extensive. With all the tools and materials gathered, you are now ready to start the repair.


Chisels are one of the most essential tools for woodworking. A chisel is a metal blade with a beveled (angled) edge that is used for carving or cutting wood. The beveled edge is sharpened to create a cutting angle. The angle of the blade determines how deep the blade will cut into the wood. Chisels are used with a wooden mallet or a hammer to drive the blade into the wood. There are many different types of chisels available, but the most common type is the flat chisel. Flat chisels have a wide, flat blade that is used for general purpose carving and removal of excess wood. The width of the blade can vary from 1/4 inch to 2 inches, and the length can vary from 4 inches to 18 inches. Other types of chisels include: -Paring chisels have a narrow blade that is used for delicate work, such as removing small amounts of wood or hewing (shaping) timber. -Bevel edge chisels have a angled blade that is used for cutting dovetails and other precision joints. -Mortise chisels have a wide, square blade that is used for making mortises (rectangular holes) in timber beams.


Most hammers are designed with a lever and a claw. The lever is the long metal or wooden handle that you grip with your primary hand, and the claw is the shorter, perpendicular piece at the end of the hammer that you use to remove nails. Some hammers have one or two additional claws on the side of the head for prying nails or boards apart.


Most rotted window frames can be repaired with a few basic tools: -Saw: Used to remove the rotted wood. A handsaw or power saw can be used, but a power saw will make the job go faster. -Chisel: Used to remove old paint and wood putty, and to score the wood so that the new putty will adhere better. -Hammer: Used to drive the chisel. -Putty knife: Used to apply wood putty. -Paintbrush: Used to apply primer and paint (optional). -Sandpaper: Used to smooth the surface of the repaired area before painting (optional).

Replacement window frame

You will need the following tools and materials: -Pry bar -Hammer -Circular saw -Replacement window frame (the same size as the one you are removing) -Caulking gun -Caulk (to match the color of your window frame) -Nails or screws (to attach the new frame to the wall)


Caulking is an important part of weatherproofing your home. You will need to caulk the outside of your window frame before painting or staining it. Caulking will also help to seal the gap between the window frame and the wall. You will need: -Caulk gun - tube of caulk - putty knife - rags


You will need paint that is the same color as the rest of the window frame. If you are unsure of the color, you can bring a sample of the frame to a hardware store or home center and ask for help in finding a match. You will also need a paintbrush, paint tray, drop cloths, and painter's tape.

Preparing the Area

The first thing you need to do is to remove any rotted wood. Use a chisel and hammer to remove any wood that is soft or spongy. Once all the rotted wood is removed, use a wire brush to remove any loose paint or wood chips.

Remove the window sash

Begin by removing the window sash. Use a putty knife to pry off the stops, and then carefully lift out the upper and lower sashes. If they’re painted shut, score the paint with a utility knife and then gently pry them open. Set the sashes aside on a drop cloth or in another area where they won’t be damaged.

Remove any trim

Before you can begin your repair, you'll need to prep the area. This involves removing any trim or siding that is covering the window frame. Use a pry bar to gently remove the trim pieces, being careful not to damage them. Once the trim is removed, you should be able to see the full extent of the damage.

Cover the floor with a drop cloth

When you are working with wood, it is always best to protect your flooring. Covering the area with a drop cloth will prevent any sawdust or other debris from damaging your floor. It will also make cleanup much easier when you are finished.

Removing the Rotted Frame

The first step is to remove the rotted frame. You will need a chisel and a hammer to do this. First, use the chisel to remove the paint around the frame. Then, use the hammer to lightly tap the chisel and start chiseling away at the frame. Once you have the frame removed, you can proceed to the next step.

Use a chisel and hammer to remove the old frame

Use a chisel and hammer to remove the old frame. Start by removing any trim or molding around the perimeter of the window. Then use a utility knife to score the paint or sealant around the perimeter of the frame. Next, use a chisel and hammer to remove the old frame. Start by prying off any trim or molding around the perimeter of the window. Then use a utility knife to score the paint or sealant around the perimeter of the frame. Once you've removed the trim, use a pry bar to remove the nails holding the frame in place. Work slowly and carefully so you don't damage the surrounding wall. Once you've removed the old frame, use a measuring tape to measure the opening for your new frame. Then use a saw to cut your new frame pieces to size. Assemble the new frame using screws or nails, then place it in the opening and secure it in place. Finally, add any trim or molding around the perimeter of the window, then caulk and repaint as needed.

Cut away any remaining rotten wood

Using a sharp chisel and hammer, cut away any remaining rotten wood from the frame. Work carefully so you don't damage the good wood. If the rot is deep, you may need to remove part of the frame.

Installing the New Frame

The first thing you need to do is remove the old frame. You can do this by prying it out with a screwdriver or a crowbar. Once the old frame is out, you need to measure the opening to see what size frame you need to get. You will also need to get a new piece of glass cut to fit the opening.

Fit the new frame into the opening

1.Put on safety goggles and a dust mask. 2. Pry off the old frame using a crowbar or a screwdriver. If the frame is held in place with nails, use a claw hammer to remove them. Pull the frame away from the opening. 3. Clean the opening of any dirt, debris or old paint using a wire brush or a sponge and soapy water. Rinse with clean water and allow to dry completely. 4. Place the new frame into the opening, making sure it is level and square. If it is not level, use shims to prop it up until it is level. 5a. For wood frames, use finishing nails to secure the frame in place. For metal frames, use screws and washers to secure the frame in place. 5b. If using screws, drill pilot holes into the frame before inserting the screws to prevent stripping of the wood or metal.

Nail or screw the frame into place

Using a nailset or screwdriver, drive nails or screws through the pre-drilled holes in the frame and into the window sill. At least two fasteners should be driven into each side of the frame. The fasteners should be long enough to penetrate the frame and enter the sill at least 1/2 inch. To avoid cracking the frame, do not overdrive the nails or screws.

Caulk around the new frame

Caulk is a sealant that helps keep water and air out of your home. Once you have the new frame in place, use a caulking gun to apply caulk around the perimeter.

Finishing Up

The last step is to putty the glass and re-install it in the window. First, clean the glass with a glass cleaner and a lint-free cloth. Next, apply a bead of clear silicone caulk around the edge of the glass. Be sure to smooth it out with your finger so that it is level with the surface of the glass. Finally, set the glass in the window frame and nail it in place.

Replace the window sash

Now that the window frame is repaired, you need to replace the window sash. To do this, you will need to remove the old sash and then install the new one. 1. Begin by removing the stop molding from around the perimeter of the sash using a utility knife. Be careful not to damage the surrounding woodwork. 2. Next, use a putty knife to loosen and remove the glass from the old sash. 3. Once the glass is removed, use a pry bar to remove the sash itself from the frame. 4. To install the new sash, simply reverse these steps. Start by inserting the new sash into the frame and then add glass and stop molding to finish up.

Add new trim, if needed

Once the rotted wood is removed, you may need to add new trim pieces to finish off the repair. To do this, simply measure and cut the pieces of trim to fit, then nail them into place with finishing nails. Be sure to add a bead of caulk around the edges of the trim before painting or staining to give a finished look.

Paint or stain the new frame to match the rest of the window

If you are painting the new frame, you will want to use a primer first and then paint it with a paint that is meant for outdoors. You can also stain the new frame to match the rest of the window.

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