Unreinforced masonry parapets

An overview of the hazard caused by unreinforced masonry parapets and potential strengthening solutions.

To find solutions that are appropriate for your building, consult a structural engineer for a professional assessment.

Unreinforced masonry parapets image
Image courtesy of Win Clark


Pieces of masonry break away or the entire parapet collapses.

Potential structural strengthening project

Option 1: drill vertical holes into the body of the wall, to well below the support level of the roof. Then grout reinforcing dowels into the holes.

Option 2: and/or fit ties horizontally through the parapet, securing them to the roof framing and/or a timber deck structure (diaphragm).

Possible first steps with a structural engineer

They assess the structural capacity of the parapet and provide specifications for the vertical dowels and/or horizontal ties.

Photo showing the parapet tied back to the roof.
Tying the parapet to the roof. Photo courtesy of Napier BSL No1 Limited.

Examples of parapet strengthening

The National Tobacco Company Building in Napier received a low NBS rating due to weakness of the parapet. The parapet was tied back to the roof structure as part of a wider upgrade project.

Read the case study