Home » House Exterior » How to Repair Rotted Window Casing – Part 3

How to Repair Rotted Window Casing – Part 3

Bob Jackson
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by Bob Jackson

How to Repair Rotted Window Casing – measure, cut and install new brick mould.

This repair is continued from Part 2.

Brick Mould Window Casing

The brick mould (also spelled “brick mold”) window casing is a standard 1-1/4 inch thick by 2 inch wide profile. New brick moulding is widely available at lumber and home improvement stores.

Old and New Brick Mould Window Casing
Old and New Brick Mould Window Casing

This is the new section of 1-1/4″ x 2″ primed finger jointed pine, fir or similar softwood brick mould casing.

Wood 1-1/4
Wood 1-1/4″ x 2″ Brick Mould Casing

Another view of the same:

1-1/4
1-1/4″ x 2″ Brick Mould Casing

The exterior walls of my home are Stucco and HardiPlank® cement board lap siding which are very durable products. The weak point in the construction is the wood trim, door and window casings. Softwoods like this brick mould will rot in a few short years of not properly caulked and painted to seal out moisture.

PVC (Plastic) Brick Mould

PVC coated and composite brick mould, trim boards, etc. synthetic products are a much better choice than wood and feature a 25 year or even a lifetime warranty. These synthetic products look and feel like wood, and are impervious to water, rot and insects. The cost of synthetics is roughly twice the cost of wood – but more than pays for itself if you have to replace wood casings.

PVC brick mould are now widely available at Home Depot, Lowes and other home improvement stores. Were I do this repair again, I would use PVC brick mould.

Measure and Saw the Brick Mould

The two sections of brick mould to be replaced is are 40 inches and 16 inches in length. I used my Dewalt Compound Miter Saw to make the clean 45-degree precision cuts that are necessary for tight fitting corners. The first step is to cut the 45° right corner for the 40 inch long top section. No measuring is necessary here because I only need to get rid of the square end of the brick mould.

Window Repair: Brick Mould Window Casing Miter Saw
Window Repair: Brick Mould Window Casing Miter Saw

I measured 40 inches from the first cut and positioned the casing so the saw kerf would be outside (to the left, or on the ‘long’ side) of the mark. The cut length of casing will then be exactly 40 inches long. Had I instead cut on the mark, the piece would be short by the width of the saw blade, maybe by 1/16″ to 1/8″.

Sawing the Brick Mould to Length
Sawing the Brick Mould to Length

The cut for the top piece of brick mould:

Brick Mould Cut to Length on Miter Saw
Brick Mould Cut to Length on Miter Saw

Compare the two 40-inch pieces of brick mould:

Old and New 40-inch Pieces of Brick Mould
Old and New 40-inch Pieces of Brick Mould

And the old and new section of 16-inch long brick mould:

Old and New 16-inch Pieces of Brick Mould
Old and New 16-inch Pieces of Brick Mould

Install the Window Brick Mould

I considered fastening the brick mould with galvanized finishing nails, but this seemed excessive given the original pieces were stapled to the window frame. It would also be very difficult to hammer a finishing nail into the edges of the brick mould parallel to the wall to secure the 45 degree corner joints – not enough clearance next to the wall, the possibility of splitting the brick mould and it would tend to separate the 45 degree miter cuts.

The solution is a brad nailer and 18 gauge 2-inch brad nails. A heavier 15 gauge brad or even a finish nailer would be better, though the 18 gauge brads are a bit thicker than the staples that I removed, so I though this an appropriate substitute. The brads are driven instantly without the jarring blows of a traditional hammer and nail. I adjusted the brad nailer to maximum depth, which set the brads about 3/32″ below the wood surface. The brads were complimented with a couple of 3″ galvanized finishing nails as in the original construction to reach the 2×4 wall studs.

Installing Brick Mould Window Casing with a Brad Nailer
Installing Brick Mould Window Casing with a Brad Nailer

I caulked the brick mould and sealed the heads of the brads and finish nails. Several other areas of the window need recaulking, too.

Window Wood Rot Repair: New Brick Mould Window Casing
Window Wood Rot Repair: New Brick Mould Window Casing

Painting the Window

The window was thoroughly cleaned, loose paint scraped, masked off and painted.

Masking and Painting the Window
Masking and Painting the Window

The completed window casing repair.

Completed Brick Mould Window Casing Repair
Completed Brick Mould Window Casing Repair

A 7-foot section of wood brick mould cost me about $8. From what I’ve read in various online forums, the labor to replace the window casing would cost $75 to $150 or more depending on the window size and other factors.

Hope this helps,

Bob Jackson

brad nailerbrick moldbrick mould installationhow to repair rotted window casinghow to replace window molding
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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