Roofing systems made of tar and gravel have been in use for over a century. "Built-up" roofs are a typical term for these roof types. Tar and gravel systems are put on the roof by laying down alternating layers of asphalt or tar and supporting materials. You have the option of selecting the number of layers (or plies) to be installed. Stone or gravel makes up the last layer of a built-up roofing structure. You can't see the underlying tar layer when standing on a gravel-covered roof. You will need to remove the entire area’s gravel to find the leak, this means extra time and cost compared to a torch on roof where you can spot examine the roof quickly. Our experts at Aldergrove roofing can spot and repair these leaks quickly and efficiently. Give us a call for a free quote.