It’s hard to believe, but given we had our first 85 degree day, summer is just around the corner. While we are out at the beach, having a few beers at a summer BBQ, or heading to our favorite lake, our roof systems are hard at work. They aren’t going anywhere (hopefully).
Summer can be one of the most punishing seasons for a roof system. While leaks often get the most attention, prolonged heat and rapid temperature swings are frequently the underlying cause of distress that develops over time. On low-slope roofs, especially single-ply systems, membranes expand as they heat up and contract as temperatures fall. Repeated cycling of that movement can place stress on seams, flashings, edge conditions, and roof penetrations. If the system is poorly detailed, aging, or already compromised, that movement can eventually lead to cracking, splitting, or water infiltration.
Surface temperature plays a major role. Anyone that has been on roofs in the summertime knows those areas can reach temperatures far above the outdoor air temperature, and that heat places considerable stress on roofing materials. The greater the temperature swing between daytime and nighttime conditions, the greater the cycle of expansion and contraction. Over time, that repeated movement can fatigue materials and open the door to failures at seams and transitions.
Material selection matters also. A roof is not just a membrane; it is a system of interrelated components that must perform together. Membrane type, attachment method, insulation configuration, cover boards, flashing details, and exposure conditions all influence long-term durability. In warmer climates, reflective roof surfaces can help reduce heat absorption and lower rooftop temperatures, which may also lessen thermal stress on the assembly. In other regions, roof system selection should be based on the building’s climate, use, and long-term maintenance needs rather than on a one-size-fits-all approach.
Roof assemblies should be designed with thermal movement in mind, particularly at perimeters, penetrations, changes in plane, and transitions between different materials. These are often the locations where cracking, splitting, or membrane separation first appear. Even a high-quality membrane can underperform if the surrounding details do not allow the system to accommodate movement properly.
Maintenance also plays a significant role in preventing heat-related damage. Foot traffic, dropped tools, windborne debris, and neglected drainage conditions can all accelerate deterioration on a roof already stressed by summer temperatures. Regular inspections help identify early warning signs such as membrane shrinkage, open laps, loose flashings, punctures, and surface crazing before they develop into more serious failures. Limiting unnecessary roof access and using designated walk pads in service areas can further reduce avoidable damage.
Insulation should not be overlooked in the conversation. Whether it is below the membrane or above it (Inverted Roof Membrane Assembly, IRMA) can be choices that affect the long term durability of the system. On replacement projects, insulation strategy often becomes especially important where existing flashing heights, thresholds, equipment curbs, and drain elevations leave little room for added thickness. In those cases, thoughtful design coordination becomes essential to balancing code requirements, performance, and constructability.
The best defense against summer roofing distress is not one single product or detail. It is a disciplined approach that combines proper design, appropriate material selection, attention to movement, protection of vulnerable areas, and consistent maintenance. Roof systems should be expected to move in summer conditions. The goal is not to eliminate that movement, but to ensure the system can accommodate it without turning seasonal stress into long-term failure. So while you are out enjoying the summer season, have confidence that your roof system is going to perform, check it out ahead of time!
Principal
Duffy Engineering
