What Causes Damaged Brick Molding?

Brick Molding

• Brick molding bridges the gap between an exterior door frame and the inside of a brick opening. The molding is approximately 1 1/2-inch square and has a face that often looks like colonial window and door casing. Other profiles, such as bead or bullnose, are often found on older houses. Brick molding is sometimes used in window openings as well.

Installation

• Brick molding should be applied so there is a gap of about 1/8 inch between it and the brick opening. Sometimes a foam spacer or wood shims are used to maintain an even gap. Brick is porous, so when it gets wet, it can transfer moisture to any wood that rests against it. The gap prevents the transfer, helping the wood stay rot-free. A bead of exterior caulk fills the gap and seals out weather.

Problems

• Brick molding is often applied directly against the brick. The resulting transfer of moisture inevitably introduces rot. If the molding is not primed before installation, especially on the ends, it may eventually rot. When caulk is not maintained, water can get behind the molding, especially if the doorway is not protected by a roof or cornice. Likewise, if failing paint is left unfixed, the molding can rot from the face. Failed flashing above a doorway can introduce moisture behind the brick.

Maintenance

• Repair peeling paint and loose caulk quickly, paying special attention to the vulnerable base of the molding. Maintain nearby flashing. When replacing small sections, slant the joint between old and new so water drains away from the house. If the molding needs to be replaced entirely, follow proper installation techniques. While polystyrene brick molding will never rot, proper installation must be assured to prevent water damage to other wood members inside the opening.