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TABLE 25. ANCHOR SYSTEM MATERIALS SPECIFICATIONS
Component Specification
Anchors
Anchors must be tested and listed to resist a minimum ultimate load of 4,725 lbs and a minimum allowable
working load of 3,150 lbs or ultimate and corresponding working load limited by soil conditions and anchor
length. The working load is the maximum load the designer can use. Ground anchors must be provided
with protection against weather deterioration and corrosion at least equivalent to that provided by a coating
of zinc on steel of not less than 0.030 oz per sq ft of surface coated.
Straps
Straps must be minimum 1-1/4” x 0.035” zinc-coated (0.030 oz per sq ft) steel strapping conforming to
ASTM D3953-97, Type 1, Grade 1, Finish B with a minimum allowable working load capacity of 3,150 lbs
and a minimum ultimate load of 4,725 lbs. Slit or cut edges of zinc-coated strapping do not need to be zinc
coated.
Stabilizer plates
The size and type of stabilizer plate, if required by the ground anchor manufacturer, will be specified in the
anchor manufacturer’s instructions. Stabilizer plates must be provided with protection against weather
deterioration and corrosion at least equivalent to that provided by a coating of zinc on steel of not less than
0.30 oz per sq ft of surface coated. Alternatively, ABS stabilizer plates may be used when listed and certi-
fied for such use.
STEP 4. INSTALL ANCHORS
Before beginning anchor installation, check for obstructions under the home such as
piers and frame members that may interfere with the tie down strapping. Check with
utility companies to determine the location of underground utilities, such as electrical
and phone lines, and water, sewer and gas pipes, that may be buried in potential an-
chor locations. Also check for homeowner-installed wires and pipes, such as those
connecting exterior lighting or sheds to the home. These must also be avoided.
FRAME ANCHORS
Frame anchors can be installed in two ways, in-line and against a stabilizer plate. The
two methods are discussed below:
In-Line Configuration
The in-line configuration (Figure 55) for homes can be used in Wind Zone I only. Typi-
cally, in-line anchors are used under high homes where the anchors can be installed
from under the home after the home is set. In-line anchors can also be installed before
the home is set, however precisely aligning the anchor with the home both vertically
and horizontally is difficult. Using swivel connectors for the strap to beam connection
can provide some horizontal flexibility.
To install in-line frame anchors, drive the anchor into the ground at an angle and loca-
tion such that a straight line can be drawn from the tip of the anchor through the anchor
head and to the connection point on the I-beam (Figure 55).
Grading area
around anchors. Anchor
heads should not rest in
sunken spots. Grade the
ground so that water does
not collect around anchor
heads, but runs away from
the anchor and out from un-
der the home. Do not bury
anchor heads.
Figure 55. In-line anchor con-
figuration
Figure 56. Stabilizer plate
configuration
Anchor alignment. Properly
aligning the anchor is critical
to performance.
Stabilizer Plate Configuration
Stabilizer plate configurations (Figure 57) are suitable for homes in all wind zones. An-
chors may be installed after the home is set. A stabilizer device, typically an ABS or
metal plate, is used to prevent the top of the anchor from slicing through the soil when
the load is applied. Stabilizer plates are available in a variety of widths. Choose the
widest plate that can be driven into the soil to maximize resistance to movement. The
LAHJ may have stabilizer plate requirements.