Scrape out the rotted wood with a chisel. Look for wood rot near the bottom of your door frame where water tends to pool during rain or floods. Remove all of the soft, rotted areas of wood by scraping it out with the tip of your chisel. Try to get every last bit of rotted wood you can see since even a small amount leftover could allow the rot to keep spreading.^[8]

Fill the rotted-out section with scrap wood or wire mesh. Filling in the space makes it easier for the filler to bond and retain its shape. Fill in as much space in the door jamb with scrap wood or wire mesh as you can. Then, secure the pieces in place with a few screws so they don’t fall out or move around.^[9]

Apply 2-part epoxy wood filler to the rotted-out section. Combine the epoxy and hardener from the wood filler on a paper plate until it has a uniform color. Use a putty knife to fill the cavity with the wood filler so it’s flush with the sides of the door jamb. Scrape the filler so it’s smooth on top of the door frame’s surface and forms a flush edge.^[10]

Let the filler dry overnight. Even though the wood filler may start hardening after a couple of minutes, it takes a few hours before it completely sets. Just leave the filler alone so it doesn’t get disturbed while it’s drying.^[11]

Sand the epoxy filler with fine-grit sandpaper until it’s smooth. Wrap your sandpaper around a piece of scrap wood so it’s easier to hold onto and use. Rub the sandpaper block back and forth over the dried wood filler to sand it down. Keep smoothing down the surface until the filler is flush with the rest of the frame.^[12]

Prime and paint the filler to match the rest of the frame. Use a paintbrush to apply a coat of wood primer to the surface and let it dry completely. Sand the primer smooth with your sandpaper so it holds the paint color better. Finally, finish up by painting your door frame with 2 coats of paint so the color matches.^[13]

Pry off the door stop and molding with a hammer and chisel. Start at the bottom of the frame and work your way up. Place the tip of your chisel in the crack between the molding and the wall, and tap it with your hammer to separate it from the wall. Keep moving the chisel around your entire door frame and removing pieces until the frame underneath is exposed.^[14]

Remove the shims behind the frame with a reciprocating saw. Shims between the wall and the frame help form a tight fit around the door. Use a reciprocating saw by holding the blade flush against the frame. Turn your saw on and guide it down between the frame and shims to cut through the nails holding them in place.^[15]

Tap the frame with a mallet to straighten it. Close the door so you can see what sides of the frame are rubbing against it. Set a flat scrap piece of wood on the warped frame and gently tap it in with your mallet. After a few taps, take a step back and check if all the gaps between the frame and the door look even.^[16]

Measure the gaps between the door and frame to see if they’re even. As you straighten the frame, use a tape measure to measure the door gaps. If all the gaps are the same, then you can stop adjusting the frame.^[17]

Reinstall the door shims and molding. You can use the same shims that were installed in your door frame before. Place the shims at hinge height in between the door frame and your walls and tap them in until they’re tight. Nail the shims in place before reattaching the trim molding with a nail gun. Secure nails every 1 foot (30 cm) to keep the trim pieces in place.^[18]

Remove the door stop and molding with a hammer and chisel. Start at the bottom of the frame and work your way up. Position the flat edge of the chisel against the seam between the door molding and the wall. Tap the end of the chisel with a hammer to lift the molding away from the frame. Then, do the same to remove the door stop nailed in the middle of the frame.^[19]

Mark 5 in (13 cm) above and below the damaged area. Measure from the edge of the damaged section with a tape measure, and draw lines on the frame with a pencil. That way, you know where to make your cuts later on.^[20]

Cut the damaged section of the frame out with an oscillating saw. An oscillating saw has a straight blade that you can use to cut through your door frame and nails holding it in place. Put on a pair of safety glasses before turning your saw on. Move the saw from side to side until you cut completely through the door jamb. After that, use a pry bar to break the section away from the rest of the frame.^[21]

Cut a piece of timber to the same size as the cutout section. Measure the length, width, and depth of the cutout in your frame. Use the same type of timber as the rest of the existing frame, which is usually a weather-treated piece that can withstand the elements. Use a hand saw to cut the wood down to the size you need.^[22]

Glue and nail the new timber into the frame. Apply wood glue to the back of the new frame piece you just cut and fit it into the opening in your door frame. Once you’ve got the new piece in place, use a nail gun to drive 2 in (5.1 cm) brad nails every 3 inches (7.6 cm). Let the glue completely dry, which will take about an hour.^[23]

Fill the gaps between the boards with caulk. Apply a bead of caulk into each of the cracks between the new and old frame pieces. Press the caulk deeper into the gaps and wipe off the excess so it’s flush with the surface of the frame. Let the caulk set overnight so it has a chance to dry completely.^[24]

Prime and paint the new timber to match the rest of the door frame. Paint a coat of wood primer over the new piece of timber and let it dry completely, which will take at least a few hours. Once the primer is dry, use the same color as the rest of the frame and paint 1–2 coats over the wood so your repair blends in even better.^[25]

Reattach the molding and the door stop. Attach the trim pieces back around the outside of your door frame with your nail gun. Place nails every 12 inches (30 cm) to secure them in place. Then, reposition the door stop trim in the middle of the frame and nail it back down the same way.^[26]

Unscrew any hardware on the door frame. If the damaged jamb has any hinges, latches, or other hardware attached to them, use a screwdriver to remove them completely. Set the hardware aside so you can reinstall it on the new jamb.^[27]

Remove the molding around the frame with a hammer and chisel. Start at the bottom of the frame and work your way up to the top. Place the flat edge of the chisel between the trim molding and the wall. Tap the chisel with a hammer to pry the molding off of the frame. Try to be careful not to break the molding so you can reuse it when you’re finished.^[28]

Pull the jamb off of the wall with a pry bar. Position a pry bar behind the jamb that you’re removing. Pry the jamb away from the wall to pull it out from your wall. Slowly work your way up to the top of the jamb and carefully pull it out when you reach the top.^[29]

Cut a new door jamb to the height of the frame with a hand saw. Measure the height, width, and depth of the door frame with a tape measure and write it down. Transfer the measurement onto a piece of weather-treated timber. Use a handsaw to trim the wood down to the right size.^[30]

Screw the door shims at the top, bottom, and middle of the frame. You can still use the old shims if they’re in good condition. Place 2 of the shims 4 inches (10 cm) from the top and bottom of the frame, and screw them into the wall frame. Then, place the third shim in the middle of the frame where the door latch lines up with it.^[31]

Nail the new jamb into place. Slide the new jamb piece into place in your door frame over the new shims. Hammer 2 nails through the jamb at each shim to secure it to the wall stud. As you attach the jamb, check it with a bubble level to make sure it’s perfectly vertical in the frame.^[32]

Reinstall the molding over the new jamb. Fit the molding back into place over the jamb. Use a nail gun to secure the trim molding every 12 inches (30 cm) so it doesn’t come loose or undone.^[33]

Cut out a hole in the jamb for the door latch. Close your door in the frame and use a pencil to mark where the door latch sits. Use a hole saw that’s about 1 inch (2.5 cm) in diameter to make a hole in the jamb so the latch catches and doesn’t swing open.^[34]