Built-up bituminous primary membranes may be comprised of three (3) or four (4) plies of organic or inorganic felt adhered with interply applications of hot bitumen.

Built-up bituminous membrane systems can be

Sheet metal flashings shall continuously cover non-granular surfaced S.B.S. membrane flashing cap sheets installed at horizontal to vertical roof junctions. Sheet metal flashings shall be installed as soon as practical to protect the membrane flashing from damage.