How to Replace Window Casings How to Replace Window Casings

What You'll Need
Replacement casings
Pry bar
Damp rag
Tape measure
Plinth blocks
Painters tape
Finishing nails, 4d and 6d
Wood putty
Sandpaper, 200-grit
Stain or paint

Window casings help to complete your window installations. They seal the gaps between the wall and window jamb. A good choice enhances the appearance of a room. Casings are generally made from wood, although plastic is also used. With time, they tend to deteriorate. Minor repairs can help to restore their fine appearance. However, it sometimes becomes necessary to replace them altogether. Follow the simple steps below to use butt joinery to replace casings.

Step 1 – Pry off the Casing

Place the tip of your pry bar between the casing and wall, at one corner on the outer edge. Lift the pry bar with gentle pressure, to dislodge the casing. Repeat a couple of times until you feel the casing loosen. Remove the pry bar from underneath the casing. Perform the same activity from the inner edge of the casing. Be careful not to damage your window. With persistent effort, the casing will soon detach from the wall. Work around the perimeter in this way, until you remove all the casings. 

Step 2 – Clean the Wall

A few nails may remain behind in the wall. Remove nails with a pair of pliers. Use a damp rag to wipe away dirt from the area occupied by the casing. Allow 1 hour for the area to air-dry.

Step 3 - Install Plinth Blocks

Spread some adhesive onto the back of a plinth block. Attach the block at one of the outside corners of the window frame. Press the block firmly onto the wall. Attach the other 3 blocks in this way. Allow the required time for the adhesive to set properly.

Step 4 – Measure and Cut New Casings

Take measurements of the distance between the blocks. Use a handsaw to trim your casings to size. Mark each piece of casing so that you know where to attach it.

Step 5 – Install the Casings

Place your first piece of casing between the plinth blocks. The casing ends should butt against the blocks. Secure the casing in place with painter’s tape. Place the other pieces of casing in their respective positions. Secure with tape. Use 4d finish nails on the inside to attach each casing onto the jamb. Space the nails 8 inches apart. On the outside, use 6d nails, spaced 16 inches apart, to attach the casing onto the wall. Remove the tape.

Step 6 – Apply Wood Putty

Fill the depressions over the nail heads with wood putty. If you intend to apply a stain, be sure to use wood putty with a similar color. Allow the putty to dry overnight.

Step 7 – Stain or Paint the Casings

Use 200-grit sandpaper to smoothen the putty. Apply a stain or paint of your preferred color. It is a good idea to apply 2 coats of stain or paint. Allow the first coat to completely dry before you add a second coat. 

Got a New Project You're Proud of?

Post it on Your Projects!