Current through Reg. 49, No. 38; September 20, 2024
(a) Proper sizing of footings depends on the
load carrying capacity of both the piers and the soil. To determine the load
bearing capacity of the soil, the installer may use any of the following
methods:
(1) Using a pocket
penetrometer;
(2) Soil surveys from
the U.S. Department of Agriculture;
(3) Values from tables of allowable or
presumptive bearing capacities given in local building codes. Such tables are
commonly available from the local authority having jurisdiction; or
(4) Any other test data from soil analysis
reports.
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(b) The footing must be placed on firm,
undisturbed soil, or fill compacted to at least 90% of its maximum relative
density is required and must be verified every 6" - 8" vertically on the
build-up. Installation on loose, noncompacted fill may result in
settlement/movement of the home and may invalidate the home's limited
warranty.
(c) Footer
Configurations.
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(d)
Footer sizing and capacities: The Footer Capacities table in subsection (a)(4)
of this section represent maximum loads and spacings based on footer size and
soil bearing capacity. Other footers may be used if equal or greater in bearing
area than those footer sizes tabulated.
(e) Piers and pier spacings: Spacing and
location of piers shall be in accordance with the tables listed in this
chapter.
(1) Spacing shall be as even as
practicable avoiding obstacles that are not in control of the installer along
each main I-Beam. Pier spacing may exceed tabulated values up to 30% so long as
the total pier count remains the same. End piers are to be located within 24
inches of the end of the main frame.
(2) Piers shall extend at least 6 inches from
the centerline of the I-Beam or be designed to prevent dislodgment due to
horizontal movement of less than 4 inches.
(3) Load bearing supports or devices shall be
registered with the Department in accordance with §
RSA
80.26 of this chapter (relating to
Registration of Stabilizing Components and Systems).
(4) Sidewall openings greater than 4 feet
shall have perimeter piers located under each side of the opening, i.e. patio
doors, recessed porches/entries, bay windows and porch posts. Perimeter piers
for openings are not required for endwalls.
(f) Pier design: Piers shall be constructed
per the details in the Pier Design.
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(1) Shimming (if
needed): Shims are commonly used as a means for leveling the home and filling
any voids left between the bottom flange of the I-Beam and the top of the pier
cap. Wedge shaped shims must be installed from both sides of the I-Beam to
provide a level bearing surface. The allowable height must not exceed 1 inch.
Shims shall be a minimum of 3"x 6" nominal. All adjustment shims (marriage and
perimeter) must be installed in manner which prevents dislodgement.
(2) Table for pier spacing without perimeter
piers.
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Graphic
(3)
Table for pier spacing WITH perimeter supports and the Perimeter Pier Front and
Side View.
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(g) Typical Multi-Section Pier Layout.
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(h)
Typical Single Section Pier Layout.
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(i)
Multi-section units mating line column supports:
(1) On multi-section units, openings larger
than 4 feet must have piers installed at each end of the opening. And within 6
inches of each end.
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(2)
Column loads for each section may be combined when the columns are opposite
each other. The footer must be sized for the combined loading.
(3) Additional piers are required under
marriage walls (see wall between column #3 and #4 in the Marriage Line
Elevation figure in paragraph (1) of this subsection. The maximum spacing is
the same as the spacing at the main I-Beams, without perimeter piers, and one
half the spacing of the perimeter piers, with perimeter piers
installed.
(4) See the table for
the mating line column loads.
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(j) Temporary support is required to insure
the structural continuity of homes placed at the retail location. Thirty (30)
days after the arrival of multi-section and sixty (60) days after the arrival
of single-section manufactured dwellings to the retail location, homes must be
temporarily lot set. If the manufacturer has instructions for temporary
blocking, home should be blocked according to the manufacturer specifications.
In absence of any manufacturer instructions, State Generic requirement, either
paragraph (1) or (2) of this subsection, shall be used:
(1) Manufacturer dwellings supported by its
running gear (left on their wheels and draw bar/hitch) shall be adequately
supported under the main beam (I-beam) of within 5 feet of each end of the
beam, within 5 feet of a supporting wheel and 10 feet on-center of each floor
section. Any required marriage line and perimeter pier locations that are
clearly marked by the manufacturer are also to be installed. Sidewall openings
less than 4 feet in length do not have to be supported. Multi-section homes
shall be sealed at the centerline and at all other openings to prevent exposure
to the elements.
(2) Manufactured
dwellings not supported on their running gear shall be adequately supported
under each main frame (I-beam) within 5 feet of each end of the home and 10
feet on-center along the length of the main beam. Any required marriage line
and perimeter pier locations that are clearly marked by the manufacturer are
also to be installed. Sidewall openings less than 4 feet in length do not have
to be supported. Multi-section homes shall be sealed at the centerline and at
all other openings to prevent exposure to the elements.
