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spacing and edge distance requirements. Failure to follow
these requirements can result in an unsuccessful fastening
and create a safety hazard.
Base Material Thickness (Fig. E)
Concrete base material should be at least three times
as thick as the fastener embedment penetration. If the
concrete is too thin, the compressive forces forming at the
fasteners point can cause the free face of the concrete to
break away. This can create a dangerous condition from
flying concrete and/or the fastener and also results in a
reduction of fastener holding power. For applications in
the face shell of concrete masonry block, select a fastener
length which will not exceed the thickness of the face shell.
Penetration
3x
Penetration
Fig. E
Fastener Penetration Guide
The following table lists typical embedment or penetration
depths expected in the base materials listed. The
penetration will vary depending on the density of the
material. This table should be used as a guide since the
consistency of these materials varies. When in doubt, a job
site performance test should be conducted.
Density
Typical Base Material
Penetration
Soft masonry
Concrete block
1"–1-1/4"
(25.5 mm–33 mm)
Average
concrete
Poured concrete
3/4"–1"
(19 mm–25.5 mm)
Dense concrete Pre-stressed/pre-cast
concrete
5/8"–3/4"
(16 mm–19 mm)
Edge Distance (Fig. F)
Do not fasten closer than 3" (76 mm) from the edge of
concrete. If the concrete cracks, the fastener may not
hold. Closer edge distances for applications such as sill
plates may be permitted if specific fastener testing has
been conducted.
3"
(76 mm)
Fig. F
Spacing (Fig. G)
Setting fasteners too close together in concrete or masonry
can cause cracking. The recommended minimum distance
between fasteners is 3" (76 mm) center to center.
Fig. G
3"
(76 mm)
Fastener Length Selection in Concrete
For permanent applications using fasteners in concrete,
first determine the thickness of the fixture to be fastened.
To this, add the required embedment or penetration
into the base material. This will be the fastener shank
length required.
For applications in the face shell of masonry block, select a
fastener length which will not exceed the thickness of the
face shell.
For removable applications with threaded studs, the
shank length required is equal to the embedment depth
required. To determine the minimum threaded length, add
the thickness of the fixture and the nut/washer thickness.
The nut and washer thickness is equal to the nominal
thread diameter.
Do not over tighten threaded parts. Maximum tightening
torque values are listed in the table below. Use of a nut
setter is recommended to reduce the possibility of over
tightening the fasteners. For critical applications, perform a
job site test.
Maximum torque for 1/4" stud (Ft.-Lbs.)
2
Maximum torque for 3/8" stud (Ft.-Lbs.)
4
Functioning in Steel
The load performance of a powder‑actuated fastener
when installed into steel base materials is based on the
following factors:
• Thickness of the steel
• Tensile strength of the steel
• Shank diameter of the fastener
• Depth of point penetration through the steel
• Fastener spacing and edge distance.
