Brick Mould Replacement: Pro Tips for DIY'ers
- Matt Weber
- 22 hours ago
- 3 min read
A common problem with exterior doors is water damage developing at the bottom of the wooden brick mould, which is the decorative trim that surrounds the door casing. Made of finger-jointed wood, the brick mould (AKA moulding or morlding) tends to wick up moisture at the ground level if it’s not properly installed. Over time, the moisture causes wood rot, and the trim starts to deteriorate.
Out with the Old
Remove the old, rotted brick mould by first cutting through all the caulk seams with a utility knife. Next, slip a scraper blade behind the brick mould at the ground level and pry it away. In some cases, the fasteners detach easily. If that’s not the case, then you can push the mould back into place and pry out the fasteners with a nail-puller before proceeding.
Pry the damaged brick mould away but leave the door casing intact. Then, use a scrape or utility knife to cut away any old caulk or paint residue from the door casing. Remove any fasteners and leave a clean surface for the new brick mould to mount against the casing.
A smart way to fix this common problem
Leave an Air Gap
Before attaching the new pieces, measure downward from the top miter point of the
brick mould. You should cut the new brick mould to allow 1/2 inch of space before
it contacts the ground. The air gap will help prevent the wood from leaching up water
into the end grain.
Seal the End Grain
After you have cut the brick mould to its final length, seal the ends of the wood at the bottom of the trim. Use a high-quality exterior sealant and work the product into the end grain. This extra step helps to protect the brick mould from water damage. We also recommend priming and/or painting all sides and edges of the brick mould prior to installing it.
In with the New
Install the brick mould by aligning the side pieces with top piece of moulding, which can usually remain in place, because only the sides typically rot.
Pro tip for tighter miters: Slip the end of a flat bar into the air gap beneath the brick mould, then step on the bar to lever the mould stick upward, closing the top miter tightly together as you drive the fasteners.
We used a 15-gauge finisher to fasten the new brick mould. Set the heads below the wood surface and fill the nail holes with exterior spackling to conceal them.
Caulk all the seams with a high-quality, exterior-grade, paintable caulk. (Silicone sealant will not hold paint).
Mask off all the trim with Frog Tape, then give everything a final topcoat of paint to renew the look of your exterior door.
SIDE NOTE
Door Casing Repair
So, you’ve let the wood rot of the brick mould spread to the door casing too… What to do now?
If this happens, we suggest surgically cutting away the rotted casing with a “buzzcutter,” a.k.a. an oscillating multi-tool (as first popularized by the Fein company).
Next, use solid PVC trim to fashion a replacement piece to the exact size and dimensions of the casing you removed. This operation will probably require a table saw to cut the replacement to the necessary width.
Also, remember to cut an angle at the bottom of the replacement PVC that matches the angle of the door sill.
Prime and paint any exposed wood around the door trim. Once the PVC replacement piece is sized to fit glove-like into the void that you cut out, nail it in place with finish nails. Seal all edges with exterior caulk before proceeding to the brick-mould replacement.
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