What is a parapet and why do old ones fail?
A parapet is the part of a wall that rises above the roof line. It is exposed to weather on both faces and across the top, which is why older ones often loosen over time.
Most masonry walls get wet on one side. A parapet gets wet on every side.
Why are parapets more exposed than other walls?
Rain and snow hit the outside face, the roof side, and the top. Water that gets in has few ways to drain. In winter it freezes and thaws inside the masonry, which can break down mortar and flake brick.
The wall is also thin and tall with nothing above it to hold it down, so it relies on good mortar and, in some buildings, on anchors tying it back to the roof structure.
Coping is the cap on top of the parapet. Flashing is the thin material, often metal, that seals the joint between the roof and the wall. Both are there to keep water out.
When coping cracks or flashing fails, water can run into the wall. Over time, it softens mortar and can rust anything steel inside.
What can you see from the ground?
Look from the sidewalk or from across the street. Do not go up on the roof to check. Concerns include:
- A parapet that leans or bows.
- Open or crumbling joints near the top.
- Loose, cracked or missing coping.
- Rust stains or white mineral deposits running down the wall.
- Brick or mortar debris on the sidewalk.
See signs a cornice or parapet is unsafe for more, and for what to do right away.
Does a roof repair fix a parapet problem?
Not always. Roof work can help stop water entering, but if the wall itself is loose or the anchors have rusted, the wall still needs attention. Roofers and masons each see part of the problem, so the cause is worth diagnosing first.
Is a leaning parapet dangerous?
It can be. A parapet can fall toward the street or toward the roof, and a loose one over a public sidewalk or entrance puts people at risk. Keep people out from under it and call. Do not lean out, climb or pull at it.
What does an engineer evaluate?
We look at the parapet, the coping and flashing, the cornice below it and the wall behind. Our parapet and chimney evaluation ends in a written report with a repair scope. Chimneys above the roof line are exposed in a similar way and can be included. We do not sell or perform repairs.
What should you send us?
Send the address and a few photos, taken from the ground or across the street. We reply within one business day.