Core Layers of a Commercial Roof
- Structural Roof Deck: The heavy-duty base made of corrugated steel, concrete, or wood that supports all upper layers and rooftop units like HVAC systems.
- Vapor Barrier: A thin plastic or specialized membrane installed over the deck to stop indoor humidity from rising and damaging the insulation.
- Roof Insulation: Rigid foam boards (such as polyiso) placed above the deck to control indoor temperatures and save energy.
- Cover Board: A tough intermediate board (like gypsum or cement board) laid over insulation to handle foot traffic and protect against hail.
- Roofing Membrane: The outermost waterproof layer exposed to the elements, commonly using materials like TPO, EPDM, PVC, or modified bitumen.
Drainage and Sealing Components
- Flashing: Thin metal sheets used around joints, edges, and penetrations to direct water away from vulnerable gaps.
- Drainage System: Includes internal drains, scuppers, gutters, and downspouts designed to remove standing water from low-slope or flat surfaces.
- Fasteners and Adhesives: Screws, plates, and industrial glues that anchor the insulation, cover board, and membrane securely to the structural deck
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