Large Mechanical Units

The details provided by manufacturers for the waterproof installation of large AHU’s often leaves a lot to be desired. Co-ordination between the trades may not be great and may result in water filtration - see Image 2. The roof membrane should go in over the top of the curb with a foam gasket between the roof membrane and the base channel frame of the AHU. 

An alternate solution using a strip of EPDM roof membrane to seal the AHU and to the curb is shown at Image 3.