Vapor Retarder. Calculate the vapor pressure and flow
direction and use vapor retarder where required. (Refer to
Insulation. Insulation must have low water absorption
and be of sufficient thickness to maintain membrane temperature
above dew point.
Waterproofing Termination. Terminate waterproofing at
8 inches (203 millimeters) above the finish wearing surface of
deck at all walls and other projections.
Flashings. All flashings must project onto horizontal
membrane a minimum 4 inches (102 millimeters) with two additional
plies of stripping and terminate a minimum of 8 inches (203
millimeters) above finished grade of the plaza deck. Require
compatible elastomeric material to provide for movement.
Percolation Course. Specify a percolation course 2
inches (51 millimeters) thick, below insulation. Use washed
smooth round river rock to drain water from insulation and to
promote free flow to drains. Insulation board with preformed
drainage channels is also acceptable.
Filter Fabric. Specify filter fabric over the
percolation or insulation course to prevent clogging from dirt or
Pavers. Specify poured-in-place concrete slab wearing
surface, pavers on mortar bed or pavers on pedestals. Pavers on
pedestals are recommended for easy access in case of leaks. Do
not specify bituminous wearing courses that require rolling for
compaction. Pavers must be set and elevated to allow sufficient
opening between joints and substrate to filter ponded water to
percolation course and into drains. Pavers should bear firmly on
all four corners.
Drains. Drains must have weep holes at every sub-
assembly level and flashed into waterproofing membrane. (Consult
drain manufacturers for special assemblies.)
Protection Boards. Require protection boards for
membrane and insulation, or both, depending on location of these