Commercial Roof Systems We shape our buildings; thereafter they shape us. -Winston Churchill

Commercial Roof Systems Commercial Roof Shapes Pitched Roof Systems Roofing Materials for Pitched Roofs Low-Slope Roof Systems Roofing Material for Low-Slope Roofs

Commercial Roof Shapes ShedGableHipGable with Dormer Low-slope Gable & ValleyHip & ValleyGambrel Roofs for small commercial buildings can be similar to residential pitched roof shapes. Low-slope roofs (not completely flat) are common in large commercial construction.

Typical Pitched Roof Roof Covering Underlayment Roof Deck Roof Framing

Roof Coverings for Pitched Roofs Standing Metal SeamClay/Cement TilesAsphalt Shingles Wood/CedarSlate Can be similar to residential construction Courtesy US Fish & Wildlife

Pitched Roof Framing (Low Rise Buildings) –Wood trusses or rafters –Light gauge steel trusses –Structural steel trusses –Open web steel joists (lower slopes) Courtesy Isle of Palms Rec Dept. Light gauge steel trusses on CMU load bearing wall Open web steel joists on tilt-up concrete walls Courtesy Greg Thiel

Low-Slope Roofs Sometimes incorrectly called flat roofs Provide small slope to provide roof drainage and to prevent ponding ©iStockphoto.com

Typical Low-Slope Roof Surfacing Insulation Roof Framing Weatherproofing Roof Decking Reinforcing

Low-Slope Roof Materials Built-up Roof (BUR) membranes –Tar and Gravel –Alternating layers of asphalt and reinforcing fabric –Aggregate surfacing Photograph provided with permission from the National Roofing Contractors Association (NRCA)

Low-Slope Roof Materials Single Ply membranes –Often referred to by chemical acronyms EPDM = ethylene propylene diene monomer –Fully adhered (glued), mechanically attached (screwed), or held down by ballast (e.g., gravel) Fully adhered EPDM roof system Ballasted EPDM roof system Photograph provided with permission from the National Roofing Contractors Association (NRCA) EPDM Photograph provided with permission from the National Roofing Contractors Association (NRCA) wikimedia

Low-Slope Roof Materials Spray Polyurethane Foam (SPF) system Two component system –Rigid closed cell spray foam insulation –Protective coating Photograph provided with permission from the National Roofing Contractors Association (NRCA)

Low-Slope Roof Framing –Wood Joists –Light Gauge Steel Joists –Open Web Steel Joists –Structural Steel –Structural Concrete Slab Open web steel joist roof framing with metal decking Couresty constructionphotographs.comconstructionphotographs.com

Commercial Roof Systems Commercial Roof Shapes Pitched Roof Systems Roofing Materials for Pitched Roofs Low-Slope Roof Systems Roofing Material for Low-Slope Roofs

Image Resources National Roofing Contractors Association (NRCA) ( U. S. Fish and Wildlife Service