How can rigid board insulation be attached to concrete roof decks in a low-slope roofing system?

Using bitumen or adhesive to attach rigid board insulation to concrete roof decks in a low-slope roofing system is the most effective method. This approach ensures a secure bond between the insulation and the deck, which is essential for maintaining the integrity and performance of the roofing system. Bitumen or adhesive provides continuity, sealing the insulation against moisture ingress and contributing to energy efficiency by minimizing thermal bridging.

Rigid board insulation is typically not simply placed on the deck, as this would risk movement and ineffective insulation performance. Mechanical fasteners can be used, but they are often less preferred for such applications due to potential points of thermal bridging and other complications they may introduce. Lastly, using nails and screws is not recommended because they can create unsealed penetrations that compromise the roofing system's waterproofing capability. Overall, bitumen or adhesive offers a reliable solution for effectively securing insulation in low-slope roofing scenarios.