This office Building roof was laid in 1988, BSS 6925 Roofing Grade with a partial coverage of BSS 1447 Paving Grade for a wheeled window washing gantry.
The gantry has been mothballed since.
Because of the differing stone content between the Roofing and Paving Grades, there has been some thermal movement and the junction is cracking in the Roofing Grade. If left to deteriorate these cracks would open up right through the 19mm thickness to the concrete substrate and cause the roof to leak.
This project was about digging out the existing cracked fillet and replacing with new Roofing Grade Mastic Asphalt.