Bexar County Public Works

Bexar County Public Works provides essential public and municipal services to a community of nearly 1.9 million citizens. Located in Texas, Bexar County encompasses the San Antonio metro and ranks 16th nationally in population. Situated along the Mission Reach of the San Antonio River, Bexar County’s new facility is part of a redevelopment program for the city’s south side.

With construction nearly complete, county officials needed to find a roof that was as aesthetically pleasing as it was reliable. It had to be tough enough to handle the brutal conditions and scorching heat of South Texas, in addition to, meeting local reflectivity requirements.

Due to previous success using Derbibrite and the proven performance of our APP modified bitumen systems, the architect recommend DERBIGUM to provide durable, long lasting waterproofing solution.


The building first received two layers of Derbiboard CA, a high performance polyiso insulation board. Besides improving thermal efficiency, Derbiboard CA provides a clean, smooth base for roofing systems. Next, a ½ inch coverboard was installed, providing an additional layer of fire resistance and hail protection. Both system layers were jointly secured using metal fasteners.

Like all DERBIGUM systems, two redundant membrane layers were installed using Derbibase Ultra (120 mil) and Derbicolor XPS-FR-CR (180 mil). Both membranes are reinforced with polyester and fiberglass mat for greater tensile strength and dimensional stability. To top it off, Derbicolor CR’s bright white granule surfacing provided an extra layer of protection while also meeting local reflectivity requirements.

As you can see, the roof had an extensive amount of drains and complex flashing details. Tapered Derbiboard systems provided positive slope to roof drains while DerbiFlash, our high performance liquid flashing made complex details waterproof. Thanks to the diligence and expertise of our DAC and technical team, Bexar County’s Public Works project was a success. Their new office space is watertight while the buildings beautiful architectural features shine through.