(57) A loosely laid water-proof membrane of elastomeric material (11) covering a flat
roof is combined with a series of hold-down devices (14) for securing the membrane
to the roof deck (12) against wind-generated uplift forces. Each hold-down device
(16) comprises a disc (17) having a domed, downwardly concave, middle portion (17a)
and a surrounding, generally flat, transverse peripheral portion (17b) the radial
width of which is equal to between about 25% and 50% of the radius of the disc as
a whole. The discs, with their concavities facing the membrane, are arranged on the
latter at predetermined spacings, being fixed in place by metallic fasteners (18)
driven through the domed portions and the membrane deeply into the roof deck. The
concavity of each disc is filled with a sealant (20), so that as each disc is pressed
down upon tightening of the associated fastener, the sealant is pressed down against
the membrane as well as inwardly against the fastener and outwardly against the peripheral
portion of the disc. An elastomeric flat ring gasket (19) may also be located between
each disc's peripheral portion and the underlying membrane.
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