A. The hot melt oil felt is usually torched down on a flat roof during the installation process.  Compared to pitched roof, flat roof tends to collect water, which is attributable to improper operations during roof construction process or the subsidence of the house resulting from the sediment of soil.

B. Many drainage pipelines of the torch down roof enter through the indoor area. When replacing the roof, particular care should be given to the installation and water proofing of the drainage pipelines.  Sometimes it is essential to cooperate with a professional plumber.

C. Some torch down roof is not installed in accordance with the three layer standard, which can cause a shortened service lifespan of the roof.