One of the common areas of air leakage in buildings is parapet air leakage. Parapets are often overlooked during the design and construction phases, but they play a critical role in the overall performance of the building envelope. Because they sit at the junction where the roof meets the wall, they create a transition point that is vulnerable to discontinuities in the air barrier system. If not properly detailed, parapets can become significant sources of energy loss, moisture intrusion, and even long-term durability problems.

Over at buildingscience.com, there is an excellent article titled “Where Roofs Meet Walls” that breaks down these issues in detail. The author explain how parapets frequently interrupt the continuity of insulation and air barriers, leaving weak points where conditioned air can escape and outside air or water can infiltrate. This not only impacts thermal performance but also increases the potential for condensation within the wall assembly, which can lead to mold, rot, and premature failure of building components.

For architects, contractors, and designers, understanding these dynamics is essential. Parapet design is not simply an aesthetic choice, it directly affects building performance and maintenance costs. By following best practices such as continuous air barrier detailing, proper insulation alignment, and water management strategies, design professionals can significantly reduce risks associated with parapets.

The article at buildingscience.com is a must-read. It highlights common mistakes, provides practical solutions, and emphasizes the importance of integrating parapets into the overall building science strategy rather than treating them as an afterthought.

Link for Where Roofs Meet Walls: https://buildingscience.com/documents/insights/bsi-050-parapets-where-roofs-meet-walls