Built-up roofing is a roof consisting of multiple plies of roof felts laminated together with a surfacing layer of asphalt. First known as "composite roofing" from the 1840's, this is one of the oldest and most reliable ways of installing a new roof. Technology has come a long way since then, and a leading company in built-up roofing felts and adhesives is Tremco. Robison Roofing is proud to be the largest authorized distributor of Tremco products in the Idaho region.
COMPONENTS
BURs come in two basic types - asphalt and coal tar - and these basic components:
- Insulation - Provides "R" value and stable substrate for a roof system.
- Base Plies - A single ply that covers the entire substrate.
- Ply Sheets - Multiple layers of plies that make up the BUR.
- Adhesive - Waterproofing that bonds the plies together.
- Surfacing - Top layer that protects the BUR.
- Flashings - Provide waterproofing around roof perimeter, equipment, and projections.
SERVICE LIFE
The service life of a flat roof is dependent on many factors: geographical location & weather conditions, foot traffic, materials used, conditions under which the roof was installed, slope of roof, type of surfacing material, etc. Under ideal conditions, a 3-ply built-up roof should last at least fifteen years, a 4-ply should last at least 20 years, and a 5-ply should last at least 25 years. We have seen ten year old 4-ply roofs that needed to be replaced and twenty year old 3-ply roofs that were still functioning.
SUPERIOR PERFORMANCE
- Thermal shock resistance prevents cracking due to temperature cycling.
- Environmentally friendly - Tar and asbestos-free
- High strength - resists external forces
- Superior elongation accommodates high movement
- High tensile strength accommodates high strength
FAQ
- How does BUR compare to other flat-roof systems?
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Expansion and contraction, ponding, moisture, thermal shock, and temperature extremes are all factors that promote premature degradation of a roofing membrane. When properly installed, BUR and rubberized BUR provide excellent service against these factors. However, there are organic materials within the BUR that will break down over time. While lifespan is slightly shorter than newer technologies such as EPDM and TPO, built-up roofs are usually the lowest-cost roofing solution available.
- How does BUR stand up against extreme temperature?
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All roofs expand and contract with temperature changes. Single-ply roofs respond with elongation. But over time these systems can lose their elasticity, resulting in buckling, ridges and splits. A built-up roof, however, limits movement with a high tensile strength in excess of 200 lbs./sq.in. The potential for fracturing is more or less eliminated.
- What is the Expected Longevity of BUR?
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Built-up roofing has been around for over 150 years. With proper installation from a reputable company such as Robison, you can expect to get between 13-17 years of reliable service from traditional built-up roof. Modified BUR contains rubber, which increases the strength and elasticity of the roof. While more costly up front, this allows your roof to last longer by adjusting to movements in the structure over time, and thermal cycling due to temperature variations.
MORE INFORMATION
Tremco Roofing - Looking for a specific product? Find the complete Tremco product line here.