26 September 2006
environmental loads, thermal cycling and frictional resistance experienced at the clips,
and the interface of the panel to the supporting structure or deck.
Minimize the use of fasteners that penetrate the weathering surface of the roof panels
and flashings. Use these fasteners in panels only at end-to-end joining and at the lower
termination point (point of fixity) of the panel. Fastening through the flat of the roof
panel in the ridge or hip areas should be concealed behind rib closures and under
flashings. Sealing washers must be EPDM (not neoprene). When fastening sheet-to-
sheet, back-up plates are required to stiffen the joint and provide solid attachment for
FLASHINGS AND PENETRATIONS.
Care must be taken that thermal movement characteristics and hydrostatic performance
are preserved. Panels should be free to cycle thermally independent of building
structure. Curbs, flashings, and penetrations should not restrict movement by pinning
the panels to the structure. With limited exception, all connections of flashings, curbs,
and penetrations must be hydrostatic in design to a minimum height of 150 mm (6 in.)
above the drainage plane, above which they may be hydrokinetic. In some cases,
especially where differential thermal movement occurs, consider using sheet membrane
material, such as EPDM, for a hydrostatic connection. When doing so, the membrane
should be protected from exposure using a sheet metal shroud flashing.
Exceptions to these practices may be where a ridge is a venting design. In these
cases, hydrostatic construction will be to the height of the panel rib seam (top of ridge
closure). Such exceptions to hydrostatic construction should be scrutinized. Concealed
sealants must be non-curing polyisobutylene tapes, supplemented with butyl tube grade
when necessary to improve flow characteristics into crevices and other difficult areas.
These compounds should be sandwiched between joint components, in concealed
locations, and not exposed. Curing compounds are not permitted. Exposed sealants
are to be high-grade polyurethane.
Round Pipes, Flues, and Soil Stacks.
Flash small, round penetrations with pre-manufactured EPDM black rubber boots
having a laminated aluminum compression ring at their base and secured at the top
using a stainless steel draw band. Application may not interrupt a seam location.
Roof-mounted HVAC Equipment.
Use minimum 2 mm- (0.080 in.)-thick aluminum or 300 series stainless steel, welded
prefabricated curbs for curb-mounted HVAC. Curb flange must underlay roof panels at
the upslope detail and overlay panels at the down slope detail. Panel seams must
terminate well before the curb wall and use built-in diverters to prevent ponding at curb