Built-up or single-ply membrane roofing systems are made up of many products and installation trades. Wood blocking at roof perimeters or penetrations, parapet coverings, reglets, roof drains, gutters, downspouts, sheet metal flashing, skylights, smoke vents, and roof hatches all need to be considered along with the roof material. Several different installation trades will need to work together on the roofing system. Inherent difficulties in the scheduling and coordination of various trades must be accounted for when estimating labor costs.

Even though it may be less expensive to use a “sustainable substitute,” the system that is specified is the one that should be estimated. If you include as part of your estimate a non-specified system and get the job, you might be required to furnish the originally specified, more expensive roof system.

Additional Considerations When Estimating Membrane Roofing

Roof Walkways - When estimating the installation of a membrane roof, be sure to include the cost for walkway pavers to create a path to roof-mounted mechanical equipment. You will more than likely be required to install these in order to obtain a warranty.

Single Ply Roofing Sources - In many locations, manufacturers make their materials available through one distributor/contractor franchise. If only one type of roof is specified, you may not have much choice as far as acquiring costs or quotes.

Sheet Metal Work - Do not assume that all sheet metal items are “off-the-shelf” items. Gutters and downspouts as well as termite shields, gravel stops, expansion joints, and reglets may need to be shop-fabricated. Checking informational catalogs could save quite a tidy sum in extras.

Read more Thermal and Moisture Protection estimating tips.