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.
Hazard
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.
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.