Abstract: A membrane type liquid containment system such as a membrane roof, pond liner and the like is disclosed wherein a large membrane is formed by adhering together individual membrane sheets at lap seams or field splices. The field splice includes a primary adhering seal formed by a splicing cement. The splice also includes a thick bead of a sealant applied between the overlapped edges. This seal acts to form a secondary or redundant seal in the field splice whereby any failure in the splicing cement or primary bond does not cause failure. A method of forming this seal is also described which permits application of the lap sealant after the cement has been applied while the cement is developing body or strength.

Abstract: A membrane roof system includes a single ply water impermeable membrane held to a roof deck by two separate fastening systems. The peripheral portion of the membrane is bonded to the peripheral edge of the roof deck by an adhesive and without mechanical fasteners. The central portion of the roof membrane is held down by traditional fastening means such as ballast, membrane-penetrating mechanical fastenings or preferably, non-membrane-penetrating mechanical fasteners. This provides maximum adherence around the periphery to withstand high uplift forces at a relatively low cost.