How to Change Window Casings

Slide a utility knife along the outer edge where the casing meets the wall. This helps to cut through any paint that may be adhering there. Slip a pry bar into the top edge of the casing and pull it away from the wall. Repeat this process to remove all the pieces of casing around the window.

Pull out any nails that remain in the wall or window jamb with a pair of pliers. Wipe down the area with a wet rag to remove dust and debris.

Dab wood adhesive on the back of a plinth block. Press it into the top corner of the window, placing it so one corner connects with the window's top corner, similar to a checkerboard. Add a second block to the other side of the window frame.

Add two more plinth blocks at the bottom edge of the window, just above the ledge. The bottom blocks should be inline with the top plinths. Let the adhesive on all four blocks dry according to the instructions on the product.

Lay one piece of casing on top of the blocks sitting over the window. Mark the inside edge of each block on the casing with a pencil. This sizes the casing for the top of the window, so it butts against the inside edges of the blocks. Cut the casing with a handsaw at these lines. Repeat the process using the top and bottom blocks to cut the side casings.

Tape each piece of casing between the corresponding blocks with painter's tape. Attach the casing to the window jambs with 4d nails and to the wall with 6d nails, adding a nail approximately every 8 inches. Once the casing is secure, remove the tape. Now you can stain the wood following the directions provided with the product.