Expansion Joint Repair for Commercial Roofs

Expansion joints in commercial buildings exist because buildings move. Thermal expansion and contraction, differential foundation settlement, and seismic loading all produce movement at the joint - movement that the rigid building structure cannot absorb and that would crack if forced. The expansion joint cover on the roof is the membrane detail that spans the joint opening and accommodates that movement while maintaining a watertight seal.

San Antonio's expansion joint environment is more demanding than most Texas cities because of the Edwards Aquifer karst limestone substrate beneath the city. Karst geology produces localized dissolution voids in the limestone that shift over time, creating differential settlement patterns that add structural movement to the thermal movement the joint was originally designed for. Buildings on the Edwards Plateau - which extends from downtown San Antonio northwest through Leon Valley, Helotes, and into the Hill Country - can experience foundation movement that is not predictable from soil borings alone. That unpredictable movement stresses expansion joint covers beyond their design accommodation, and it is why we see expansion joint failures on buildings that are only 10 to 15 years old in San Antonio when the same joint detail lasts 25 years in a city on stable alluvial soils.

We repair and replace expansion joint covers on TPO, EPDM, and modified bitumen systems. We specify joint covers designed for the anticipated movement at each joint - which requires understanding the building's structural system and the movement history we observe at inspection, not just installing a standard-width cover over the existing condition.