Home » House Exterior » How to Repair Rotted Window Casing – Part 1

How to Repair Rotted Window Casing – Part 1

Bob Jackson
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by Bob Jackson

This project explains how to repair a rotted window casing with new sections of brick mould (a.k.a. “brick mold”).

How to Repair Rotted Window Casing

The single-light fixed transom window is on the south side of the house. I noticed the paint was peeling and the window casing was starting to rot in the top left corner. Water apparently had worked its way into the corner seam or wicked in at one of the metal staples that fastens the casing sections together.

The window casing is a standard profile 1-1/4″ thick by 2″ wide brick mould. A new section of brick mould was readily available at the local home improvement store. The repair steps are:

  1. Remove the rotted window casing.
  2. Cut and install new window casing.
  3. Caulk and paint.

The most challenging part is removing the old window casing without damaging the window.

Cut the Brick Mould Caulk Seams

The caulk seams are cut to separate the brick mould window casing from the wall and the interior window frame. A utility knife is perfect for the job.

Cut the Window Caulk Seams with a Utility Knife
Cut the Window Caulk Seams with a Utility Knife

Cut along the inside caulk lines of the window casing.

Cut the Inside Caulk Seam to Release the Window Casing
Cut the Inside Caulk Seam to Release the Window Casing

Remove the Brick Mould Staples and Nails

The brick mould window casing is fastened with several 2 inch staples in the corners and the face of the window casing. The casing apparently was pre-assembled at the factory and came as a single unit with the window. The staple divots in the casing haven’t been sealed with caulk – an invitation for water to wick in, rust the staple and rot the wood.

Staples Fasten the Corners of the Window Casing
Staples Fasten the Corners of the Window Casing

A close look at the face of the window casing reveals the location of additional staples and finish nails that have been caulked and painted over. I used the utility knife to dig out the wood around the staples and nails so I could pry them out.

Revealing the Staples and Nails in the Window Casing
Revealing the Staples and Nails in the Window Casing

A screw driver is driven under the staple to pry it out.

Prying out a Staple with a Screw Driver
Prying out a Staple with a Screw Driver

The finish nail is pulled with a nail puller tool. The pincer head of the nail puller is driven under the nail head until it “bites” into the nail shaft. Finish nails have very small heads and it’s easy to strip the head if the tool isn’t driven securely onto the nail shaft.

Pulling a Finish Nail with a Nail Puller and Hammer
Driving in the Nail Puller

Pulling the finish nail from the window casing.

Pulling the Finish Nail from the Window Casin
Pulling the Finish Nail from the Window Casing

Staples and nailed pulled from the brick mould window casing.

A careful reader will note there is are two (2) staples in the corners that I haven’t pulled, one each in the bottom window casing and another in the top window casing under the drip cap. The staple under the drip cap is in the rotted wood section and will fall away. The staple in the bottom section of the window casing wasn’t remove because I don’t want to damage this good section of casing. I’ll pull the casing out and up leaving the staple in the bottom section of casing, to be tapped out with hammer later.

Staples and Nails Pulled from the Brick Mould Window Casing
Staples and Nails Pulled from the Brick Mould Window Casing

The brick mould is easy to pull away from the window frame. That last staple in the bottom corner is all that now holds the casing. A couple of upward pulls and the casing came off the staple. The staple was then tapped out of the good section of bottom casing with a hammer.

Exterior Window Frame Repair: Pull Off the Rotted Window Casing
Exterior Window Frame Repair: Pull Off the Rotted Window Casing

The good news is the rot is limited to the casing and did not affect the window frame or wall studs.

Exterior Window Repair: Rotted Section of Brick Mould
Exterior Window Repair: Rotted Section of Brick Mould

This project is continued in Part 2.

Take care,

Bob Jackson

brick moldbrick mold repairfix window rot damagehow to repair rotted window casingreplace window casing
Bob Jackson
Bob Jackson
Technology product manager by day and a prolific handyman in the evenings and over the weekends. Bob was the founder of the original Handyman How To website and that tradition continues on this site with excellent new handyman content into the future.
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