Quick Facts - Built-Up Roofing Systems
 | Redundancy is the key to Built-Up Roofing (multiple layers - i.e. "Built-Up"). |
| Three componants: Waterproofing (bitumen), Reinforcement (felts), Surfacing (aggregate, coatings) |
| Bitumen: Breakdown of usage in the roofing industry is as follows: > 90% Steep & Special Steep Asphalt, 5% Coal Tar Pitch, < 5% Other Asphalts. |
| BUR Felts: Used for reinforcement, puncture resistance, multiple layers of waterproofing, to span gap in substrate, and to improve fire ratings. |
| Breakdown of felt usage types is as follows: 92% fibrous glass, organic 5%, polyester 3%. |
| Organic Felts: Made from scrap paper. In the past, were made from cotton fibers. Perforated to vent gases. |
| Fibrous Glass Felts: Glass mat is coated. These fibers are not absorbsive and need a release agent. |
| Polyester Felts: Non-woven, uncoated, and can be applied in cold or hot adhesives. |
| Surfacings: Flood Coat & Gravel, Glaze Coat, Cold Coatings, Cap Sheets. |
Source: The Roofing Industry Educational Institute