Oftentimes, building owners and homeowners prepare for hurricanes by boarding up windows and doors to minimize property damage and flooding.
But what about the roof? Despite being a critical component of the building envelope, roofs often fall under the “out of sight, out of mind” mentality and can be a forgotten part of storm preparation.
Aside from the roof’s vulnerability during high wind events, rooftop equipment that’s not properly attached is also highly susceptible to becoming displaced during hurricanes and seismic events. Numerous potentially dangerous issues can result, including:
- Puncturing and tearing the roof membrane
- Water intrusion, causing interior finish damage, operational outages, loss of stored product and increased risk of mold or mildew growth
- Increased fire risk
- Potentially injuring people on the ground below
The Federal Emergency Management Agency (FEMA) notes several examples in its Hurricane Katrina Recovery Advisory of rooftop equipment being displaced or blown from the roof following several hurricanes. FEMA issued another advisory in 2018 to provide additional guidance and recommendations to enhance wind resistance of rooftop equipment in high wind regions after Hurricane Irma and Hurricane Maria.
The advisories prompted further revisions to the International Building Code (IBC) to include language concerning the proper installation of rooftop equipment. Several versions of the IBC, International Mechanical Code (IMC) and ASCE 7 reference the design, construction, erection and installation of mechanical appliances, equipment and systems. Requirements include consideration of structural design, wind loads and seismic loads. The 2022 edition of ASCE 7 now includes a chapter on tornado loads.
Although existing building codes have provided some guidance on rooftop attachment, more is needed to help outline best practices and eventually standardize the installation of attachment systems.
Recently, engineered solutions for rooftop equipment installation have emerged as effective alternatives to traditional methods. The engineered attachment methods are minimally invasive to the roof system and provide a continuous load path of sufficient strength and stiffness between the component and the supporting structure. They also address code requirements and minimize the potential for property loss and life safety concerns.
When determining attachment type and functionality, it’s important to evaluate the overall project requirements, including code, wind and seismic loads (tensile, shear and compression) and differential movement when determining the attachment type and functionality. Best practices for rooftop equipment attachment will vary by attachment methodology and roof system type.
Follow these recommendations for optimal results:
- Follow the manufacturer’s installation instructions and specified roofing material before installing
- Consider material and component compatibility and its impact on the manufacturer’s warranty
- Installation should be performed by a professional roofing contractor familiar and experienced with installation of the attachment components
- Ensure the engineered solution can handle the proper loads (i.e., tensile, shear and compression) and ensure proper fastener selection
Find a checklist of key topics to consider for proper rooftop equipment attachment.