Field operations, such as lap-jointing between sheets and attachment at flashings and roof penetrations, need special care for proper sealing. Particular attention to the perimeter attachment is also required since this is where wind uplift failures have been known to originate. In the past decade, hundreds of new roofing and waterproofing materials have appeared on the market. Their classification can be done in different ways. In this Digest they are grouped in generic classes that have been used for preparing material and application standards.
Rubberized asphalt is basically a compound of virgin or reclaimed rubber dispersed in asphalt.
The rubber gives improved flexibility at low temperatures and controls flow or creep at high temperatures. Oil is used as a plasticizer, clay or limestone powder is used as a filler, and a stabilizer protects the rubber from deterioration. The material is produced in the form of cakes wrapped in low-density polyethylene that can be stored tor a long time. On the job site, the package is melted in a kettle. The polyethylene wrapping melts with the rubberized asphalt, improving its physical properties.