CertainTeed Yosemite Venting Base Sheet is designed for use as a buffer sheet over existing roofing membranes in lieu of a divorcing layer of roof insulation on re-cover projects where the existing roofing membrane is left in place. It is suitable for use over existing gravel, mineral or smooth surfaced roof systems and is substituted for the base ply of the new membrane.
CertainTeed Yosemite Venting Base Sheet is manufactured on a heavy duty fiber glass mat which receives a heavy coating of weathering grade asphalt and is surfaced with mineral granules. The heavy asphalt coating provides excellent moisture resistance in conjunction with a durable, puncture resistant granule surface.
CertainTeed Yosemite Venting Base Sheet may be applied in either a spot mopping of hot asphalt or with mechanical fasteners, depending on the type of existing membrane and substrate. The existing membrane surface must be prepared in accordance with CertainTeed's reroofing specifications prior to application of Yosemite Venting Base Sheet.