What a Brick Parapet Wall Is—and What Keeps It Sound

A brick parapet wall is an upstanding wall with brick masonry that extends above the roof edge. From the street, it forms the raised roofline; from the roof, it borders some or all of the perimeter. On older masonry buildings, it may be a continuation of the front wall above the roof eaves. The coping is the protective cap on top—not the parapet itself. (MBIE guidance)

Understanding a parapet means looking at two systems together: the masonry and its restraint, and the weather protection where wall meets roof. Sound-looking brickwork does not prove that either system is complete.

What is behind the brick face?

“Brick parapet” describes the visible material and position, not a single construction method. An older parapet may be solid, multi-wythe brickwork—a wythe is one vertical thickness of masonry. Another may have a cavity between masonry leaves, or a brick veneer tied to a separate backing.

That distinction matters for water management. Mass masonry holds absorbed moisture and releases it during drying. A drainage wall instead collects water behind the outer brick leaf and directs it out through flashing and weeps. Repair details must suit the actual assembly; a modern cavity-wall detail is not automatically appropriate for a solid historic parapet. (Brick Industry Association Technical Note 7)

For repairs, establish the wall thickness, backing, connections and existing flashing before specifying replacement work. The visible bond pattern alone is not a sufficient construction record.

How the weather protection works

A parapet exposes the top of the wall as well as its faces. Its rainwater protection has three distinct jobs.

1. The coping sheds rain

Stone, concrete, brick or metal can form the coping. The important features are a shedding surface, protected joints and edges that throw runoff clear of the wall. Building Science Corporation recommends sloping roof-parapet copings inward toward the roof and providing drip edges on both sides, reducing runoff staining on the façade. A waterproof membrane beneath the coping provides protection when its joints leak. (Parapet water-management guidance)

BIA likewise recommends flashing immediately beneath the coping and prefers metal copings for moisture resistance. (BIA Technical Note 7) That preference is not a blanket reason to discard sound historic stone or brick caps. Conservation guidance favors retaining historic materials and repairing deteriorated features rather than replacing them where feasible. Consider the existing material, appearance and repairable water-shedding detail together. (NPS rehabilitation standards)

2. Flashing protects the roof-to-wall junction

The roof waterproofing turns up against the parapet. Where that roof flashing has an exposed upper edge, counterflashing overlaps and protects it so water cannot readily run behind it.

The wall construction determines the complete detail. BIA distinguishes counterflashing at a solid barrier wall from the through-wall flashing and counterflashing needed at a brick-veneer drainage wall. Masonry and roofing work must therefore be coordinated, rather than treating the junction as a seam to fill with sealant. (Roof/wall intersection details)

3. Water that enters needs an exit

In a cavity assembly, flashing collects water and weeps let it escape. Blocked drainage defeats that arrangement. In a solid wall, drying depends on the masonry and mortar rather than on a cavity that may not exist.

Prolonged wetting can contribute to freeze–thaw damage in susceptible masonry and corrosion of embedded metal. Replacing flaking brick without correcting a leaking cap or roof junction leaves the exposure unchanged. (BIA moisture guidance) See the separate guide to diagnosing brick spalling for the material failure itself.

Inspection and repair priorities

Start from a safe viewing position. Do not lean on suspect masonry or approach an unprotected roof edge to inspect it. Ask a suitable roofing or masonry professional to check:

• The top: cracked or displaced coping, open joints, loose metal caps and failed attachments.
• The roof side: separated flashing, torn waterproofing and staining below junctions.
• The masonry: eroded joints, loose bricks, cracking, bulging or leaning.
• The drainage: obstructed roof outlets and, where present, blocked weeps.

Visible leaning, displaced masonry or loose coping above occupied areas calls for keeping people clear of the potential fall area and arranging prompt assessment. For leaning or displaced wall masonry, involve a structural engineer—not only a repointing contractor.

Unsecured, unreinforced masonry parapets are particularly vulnerable in earthquakes. New Zealand’s MBIE guidance describes securing them back into the building, with the solution dependent on its roof and structural arrangement. Repointing is not a substitute for that restraint. These securing concepts require project-specific engineering; they are not a universal retrofit detail. (MBIE parapet guidance)

For a stable parapet, repair the water-entry defect before—or as a coordinated part of—masonry repairs. Repoint deteriorated joints with mortar compatible with the existing brick and mortar, not simply the strongest available mix. National Park Service guidance requires historic repointing mortar to be softer and more vapor-permeable than the masonry units, and no harder or less permeable than the historic mortar. (Preservation Brief 2)

Use brick-pointing guidance for joint preparation and matching. If rebuilding or strengthening is necessary, have the masonry, restraint, coping and roof flashing detailed together—including weatherproofing around new fixings. Check local structural and heritage requirements before altering the wall’s height, profile or construction.