Council Chambers Re-roof
This roof was an old Malthoid roof covered with a layer of Stone Ballast. The building is approximately 60 years old with the flat roofing system being of a similar age. This roof type was commonly used at the time and the stone ballast cover was essentially used to protect the flat roof membrane from U.V degradation. Upon inspection we found that the membrane itself was very brittle and easily damaged once exposed to the elements. The roof substrate in this case was an aerated light weight form of concrete. The brief was such that the client did not want to expose the underlying roof structure for a long period of time. We elected to leave the current membrane in place and use a mechanically fixed roofing membrane. This required removal of the ballast and a thorough inspection and clean of the roof. We also used a mould killer to kill any mould spores, this was left for a period of time before the re-roof work was carried out.
Mechanical fixing of the membrane was chosen because we knew that the roof substrate was somewhat saturated with moisture which had accumulated beneath the existing membrane. By mechanically fixing (as opposed to fully bonding) we allowed any moisture to freely move under the membrane and naturally dissipate.
Note the deterioration of the membrane surface. this system was well beyond its service life.