Dow Protected Membrane Roof EN - Manual (Page 12)

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Components
P A V E R S
Description
Concrete slab pavers or inter-
locking pavers can be used to
supplement or replace conven-
tional stone ballast requirements
and create a surface for rooftop
decks, walkways, terraces, gardens
and similar applications.
Note: For structural plaza deck
design, such as for parking decks
and other high-traffic areas, the
design is the responsibility of an
architect and/or structural engineer.
Function
Note: For additional information,
see “Ballast” on page 10.
Narrow roof walkways for
access: Pavers can be placed to
facilitate access to rooftop
equipment.
Prevent wind scouring: In
exposed areas or areas of high
winds, pavers may be required.
In certain conditions, the pavers
should be strapped together
using galvanized or stainless
steel straps, mechanically fas-
tened to each paver.
Perimeter ballast: Additional
ballast is required around the
building perimeter in a PMR
design. Depending on the
design, pavers can be installed
instead of conventional stone
ballast.
Plaza deck design: For light
traffic requirements, the stone
ballast can be replaced with
concrete pavers completely. In
many cases, the pavers must be
raised from the surface of the
fabric and insulation. See
“Installation Notes” for details.
Specification
PAVERS
Concrete pavers shall be man-
ufactured from minimum 3,000
lb/in
2 (210 kg/cm 2 ) concrete
with a minimum weight of 18
lb/ft
2 (88 kg/m 2 ).
Pavers should be placed on
pedestals to ensure a “diffusion
open” design. The pedestal can be:
• 1" (25 mm) thick insulation
cut into 6" (150 mm) square
blocks and placed under the
four corners of the paver
(limited to 108 lb/in
2 [7.6 kg/cm 2 ]
live loading)
• Preformed pavers with at least
a 3/16" (5 mm) foot in each
corner or ribbed undersurface
• Paver pedestal of injection
molded, weathering-grade plastic,
installed under each corner
(e.g., PAVE-EL by Envirospec Inc.,
Terra-Tabs by Wausau Tile, etc.)
• Layer of pea gravel 1" (25 mm)
(min.) free of fines
Note: This air space is not required
if the pavers are covering only a
limited area (less than 10 percent
of roof area), such as corners or
narrow roof walkways.
PAVER STRAPPING AND
FASTENERS (IF REQUIRED):
Straps shall be of 22 gauge
galvanized or stainless steel, 3"
(75 mm) wide and 12' (3.6 m) long.
Fasteners shall be 1/4" x 1-1/4"
(6 mm x 32 mm) corrosion-
resistant metal anchors, expanded
in pre-drilled holes (e.g., Zamac
Nailin #2814 by Powers
Fasteners, Inc).
Installation Notes
Pavers should be placed on
pedestals. In colder climates, the
air space will minimize any
freeze-thaw spalling on the
concrete and moisture build-up
in the insulation due to vapour
drive from the inside.