News & Advice

The number of layers in a commercial roof varies; a typical built-up roof may have 3-5 layers, while single-ply roofing systems have one layer.

Overview of the layers typically present in a commercial roof…

1. Structural Decking – The structural deck is the foundation of the roof and provides support for the roofing materials. It is usually made of plywood, OSB, or steel and serves as a base for other roofing layers.
2. Underlayment – The underlayment, positioned atop the structural decking, acts as a waterproofing shield to prevent water infiltration. It can be made of asphalt-saturated felt, synthetic membranes, or self-adhering membranes, safeguarding the roof deck from moisture-related harm.
3. Insulation – Insulation helps regulate indoor temperatures, reduce heat loss/gain, and prevent condensation in the roof assembly. Common materials include foam boards, fiberglass batts, and spray foam insulation.
4. Membrane – The roof membrane is a waterproof layer made of single-ply materials like EPDM, TPO, PVC, or modified bitumen. It protects against water, UV radiation, weathering, and chemicals in commercial roofing systems.
5. Cover Board – Cover boards can be installed in commercial roofing systems to enhance durability and provide extra protection. They are made of materials such as gypsum, fiberglass, or composites and improve puncture resistance and fire performance.