For Attaching Base Ply, Recovery Board and Insulation to Cementitious Wood Fiber, Poured Gypsum Decks, and LWIC (Light Weight Insulating Concrete).
CompositionFactory preassembled components consisting of:
Fastener density and spacing vary depending on applicable uplift requirements. Local
codes, governing approval bodies, membrane manufacturers, and individual roof deck
manufacturers all may have specific requirements that need to be addressed prior
to beginning any roofing project. The Locking Impact Nail should always be embedded
into the structural roof deck to a depth of at least 1”. The following illustrates
typical Factory Mutual recommended fastening patterns widely accepted by membrane
and roof deck manufacturers.
Base Ply Attachment for built-up or modified bitumen roof covers.
Class I-60, I-75, or I-90 Windstorm Classification. An FMRC Approved base ply is fastened in the field of the roof with Locking Impact Nail installed 9” on center in the 2” wide base ply side laps and 18” on center staggered in 2 rows, equally spaced, between the base ply side laps. When fastening meter-wide material with this pattern, expect to use approximately 86 fasteners per square (100 ft.2).
Fastening Guide 2
Recovery board and Insulation attachment under built-up and modified bitumen roof
covers. Class I-90 Windstorm Classification. An FMRC Approved Recovery Board/Insulation
suitable for use with minimum 3 ply built-up or modified membranes is attached with
8 Locking Impact Nail fasteners per 4’x 4’ board in a diamond-in-a-box pattern.
(1 fastener per 2 ft.2) Consult FMRC for a complete listing of approved recovery
Fastening Guide 3
Recovery board and insulation attachment under fully adhered single ply membranes.
Class I-90 Windstorm Classification. An FMRC Approved Recovery Board/Insulation suitable for use with fully adhered single ply membranes is attached with 12 Locking Impact Nail fasteners per 4’x 4’ board in 4 rows of 3 fasteners per row. (1 fastener per 1.33 ft.2) Consult FMRC for a complete listing of approved recovery boards/insulations.
All documents are U.S. English unless otherwise noted