As property prices rise, many households have had flat roof extensions and converted garages to living areas rather than move to a larger more expensive home.
Most of the old flat roofing material is mineral felt bonded to the boards with heated tar then coated with gravel to give protection from sunlight. It has an approximate lifespan of around 15-20 years.
Over time the felt becomes brittle and the gravel loosens and is washed into the gutters. Moss grows on the gravel adding weight to the surface and preventing it drying out. Eventually it may spring a leak and need to be repaired or replaced.
There are many alternative solutions with prices across the spectrum and varying degrees of success. It pays to be diligent and make sure you get the right product and service to meet your budget.