Orange County Motor Pool Roof Replacement

Atlas provided roof replacement design, bidding assistance, and CA for the Orange County Motor Pool. The generally one-story building consists of approximately 11,000 square feet of roof area with a 4:12 slope draining to perimeter gutters with downspouts discharged to grade. The existing system was likely original to the 1996 construction and consisted of asphalt shingles over underlayment, OSB, rigid insulation, tongue-and-groove cementitious wood fiber (Tectum) deck, supported by steel roof structure.
The building was non-conditioned space at the time, however, the County intended to provide heating and cooling in a future project. The existing system did not meet thermal code requirements for conditioned space, so Atlas designed a system with added insulation to meet the future needs of the building. Additionally, the existing system did not include a vented deck, and while this is not required by code, it is recommended by shingle manufacturers and is generally accepted as best practice in the industry. A vented deck minimizes excessive heat build up in the system and prolongs the life of the shingles.
The new system designed by Atlas included architectural asphalt shingles over synthetic underlayment, a vented nail base with rigid insulation on existing OSB, rigid insulation, and Tectum deck. However, due to material shortages, prefabricated vented nail bases were unavailable and the Contractor had to construct the vented nail base on site. Additionally, to accommodate the added system height, Atlas carefully designed and ensured proper installation of roof to wall details which modified the existing EFIS.