When it comes to commercial roofing, building owners have lots of options.
Built-up roofing (BUR) systems have been in use in the U.S. for well over 100 years. They are essentially manufactured or “built” on the rooftop by the contractor, by alternating multiple layers or “plies” of asphalt or tar between layers of felt or synthetic materials. They are often covered with gravel or other ballast for protection from the sun.
In the 1960s and 70s, a number of market forces drove the development of alternatives to BUR, in particular, single-ply membrane roofing systems.
Single-ply membranes are flexible sheets of synthetic materials that can be manufactured from a variety of bitumens, polymers, fillers, plasticizers, stabilizers and other elements.
Modified bitumen membranes – evolved from built-up roofing – are factory-manufactured layers of asphalt that are “modified’ using plastic or rubber components and reinforced with a fabric layer. Thermoset membranes are essentially rubber, known as ethylene propylene diene monomer, or EPDM. Thermoplastic membranes are typically either polyvinyl chloride (PVC) or thermoplastic polyolefin (TPO). All of these single-ply systems have gained market share from BUR over the past 50 years.
The growing single-ply industry eventually formed its own organization: Single-Ply Roofing Industry or SPRI. For more than 35 years, SPRI has been a technical and statistical authority on single-ply roofing; an invaluable resource for building owners and managers, architects, roofing consultants and other specifiers, contractors, and other industry stakeholders. To improve roofing knowledge and best practices, SPRI works on a variety of industry issues, including product quality, installation practices, and worker training.
From the SPRI website:
SPRI is a collection of commercial roofing industry experts dedicated to providing an open forum for discussion, education, and innovation. We provide ongoing resources and expertise for contractors, architects, and building owners.
We are the leading authority in single-ply roofing. Our network deals exclusively with thermosets, thermoplastics, and modified bitumens. Here, you’ll find easy access to online publications and documents that range from generic technical guidelines for design and application to general information about roof maintenance and emergency repairs.
Who is SPRI?
- Regular Members manufacture or market flexible sheet membrane roofing systems; but not including independent manufacturers’ representatives or distributors.
- Associate Members manufacture and market, or simply market, raw materials, components, accessories, tools or equipment used in flexible sheet membrane roofing systems.
- Affiliate Members are professional roof consultants, architectural firms, specifiers, product distributors, sales representatives, testing agencies and research agencies.
To learn more about the Single Ply Roofing Industry, visit the SPRI website at www.spri.org.