When Does A Parapet Wall Need To Be Repaired Or Rebuilt?

A parapet wall is the section of masonry that rises above the roofline, and it shows up all over Greater Boston, from Back Bay brownstones and South End row houses to commercial blocks in Quincy and triple-deckers in Somerville. Because a parapet is exposed to rain, wind and sun on both faces, it usually wears out well before the walls beneath it. JMS Masonry & Restoration provides brick parapet wall repair and rebuilding to the Greater Boston area, and this guide covers the warning signs our team looks for and how to tell whether a wall can be repaired or needs to come down and go back up.

TL;DR: Cracked mortar, loose coping and small leaks can usually be repaired, while a parapet wall that leans, bows or has widespread brick damage typically needs to be rebuilt.

What Is A Parapet Wall?

On a flat roof, the parapet wall serves as a guard at the roof edge, a fire barrier between neighboring buildings and a finishing detail on the facade. The top is covered by a coping or parapet cap made of stone, brick, terra cotta or metal. The Brick Industry Association's Technical Note 36A points out that caps and copings sit in one of the most exposed spots on any structure, which is why slope, drip edges and flashing at the top of the wall matter so much.

Being a parapet wall in New England isn’t easy. Fall rain soaks into the brick, freezes overnight and expands inside the wall. The street side of a roof parapet wall often gets full sun while the roof side stays shaded and damp, and that uneven heating and drying works on the mortar joints year after year.

Signs Your Parapet Wall Needs Repair

Many parapet problems start small and stay manageable when they are caught early.

Eroded Or Cracked Mortar Joints

Mortar that has recessed, crumbled or cracked lets water into the core of the wall. When the brick itself is still sound, brick repointing is often the right fix. The National Park Service's Preservation Brief 2 recommends replacement mortar that matches the original in strength and makeup, which is especially important on older buildings laid up with softer lime mortar.

Loose Or Cracked Coping

Coping stones that rock under light pressure, open joints between caps, or a metal parapet cap that has pulled away all give water a direct path into the top of the wall. Resetting the coping and replacing worn flashing is a common repair that can help avoid much bigger damage below.

Leaks, Stains, And Efflorescence

Water stains on top floor ceilings, white salt deposits on the brick and spalling brick faces near the roofline usually point to moisture moving through the parapet. Our article on efflorescence on brick explains what those white deposits mean and where they come from.

When A Parapet Wall Needs To Be Rebuilt

Repair works when the structure of the wall is still sound. A rebuild becomes the better option in situations like these:

• The parapet leans or bows toward the roof or the street

• Large sections of brick are cracked, spalled or loose

• Horizontal cracks run along the base of the parapet

• Earlier repairs with hard cement mortar have damaged the surrounding brick

• The flashing built into the wall has failed along most of its length

A leaning parapet is a safety concern as well as a water problem. Loose brick at the roofline can fall onto sidewalks and neighboring roofs, so many owners in Boston and Cambridge treat a bowed parapet as a priority. 

How Our Team Approaches Parapet Wall Repair In Boston

Every project starts with a parapet wall inspection from both the roof side and the street side, since damage often shows up on one face before the other. From there, we lay out whether targeted repointing, coping work or a partial rebuild makes the most sense for the building and the budget. On older properties, JMS Masonry offers historic masonry restoration that keeps the original character of the facade intact.

Timing plays a role too. Mortar needs moderate temperatures to cure properly, so most parapet work in Massachusetts is scheduled between spring and fall. Late fall is a smart window for an inspection, since it gives owners time to plan repairs before winter freeze and thaw cycles turn small cracks into larger ones.

Schedule A Parapet Wall Inspection In Greater Boston

Property owners in Boston, Cambridge, Brookline, Newton, Somerville, Quincy, Lynn and surrounding communities can count on JMS Masonry for parapet wall repair, coping replacement and full rebuilds. With more than 25 years of hands-on masonry experience behind our work, our team will explain what your parapet needs and why, right on site. Call 781-435-0498 or request an estimate to get started.