(A) Soil
conditions
.
To help prevent settling or sagging, the foundation shall be
constructed on firm, undisturbed soil or fill compacted to at least ninety per
cent of its maximum relative density. In any site, all organic material such as
grass, roots, twigs, and wood scraps shall be removed from the underneath of
the manufactured home and in areas where footings are to be placed. In an
existing site, all organic material such as grass, roots, twigs, and wood
scraps shall have been removed in areas where footings were placed. The home
site shall be graded or otherwise prepared to ensure adequate drainage in
accordance with this rule.
(B) Soil classifications and bearing
capacity.
The soil classification and bearing capacity of the soil shall
be determined before the foundation is constructed and anchored. The soil
classification and bearing capacity shall be determined by one or more of the
following methods:
(1) Soil tests.
Soil tests that are in accordance with generally accepted engineering
practice;
(2) Soil records. Soil
records of the applicable authority having jurisdiction;
(3) Soil classifications and bearing
capacities. If the soil class or bearing capacity cannot be determined by test
or soil records, but its type can be identified, the soil classification,
allowable pressures, and torque values shown in the following table may be
used;
Soil Classification Table 2.1 of
4781-6- 03.2
|
Soil Classification No.
|
Soil
Classification ASTM D2487 or D2488
|
Soil Description
|
Allowable Bearing Pressure (psf)1
|
Blow Count
ASTM
D1586
|
Anchor Torque
Probe3 Value4
(inch-pounds)
|
|
1
|
-
|
Rock or hard pan
|
4000+
|
-
|
-
|
|
2
|
GW, GP, SW, SP, GM, SM
|
Sandy gravel and gravel; very dense and/or cemented
sands; coarse gravel/cobbles; preloaded silts; clays and coral.
|
2000
|
40+
|
(6)
|
|
3
|
GC, SC, ML, CL
|
Sand; silty and; clayey sand; silty gravel; medium
dense coarse sands; sandy gravel; and very stiff silt, sand clays.
|
1500
|
24-39
|
351-650
|
|
4A
|
CG, MH2
|
Loose to medium dense sands; firm to
|
1000
|
18-23
|
276-350
|
|
|
|
stiff clays and silts; alluvial fills.
|
|
|
|
|
4B
|
CH, MH2
|
Loose sands; firm clays; alluvial fills.
|
1000
|
12-17
|
175-275
|
|
5
|
OL, OH, PT
|
Uncompacted fill; peat; organic clays.
|
(7)
|
0-11
|
(5)
|
Notes:
1. The values
provided in this Table have not been adjusted for overburden pressure,
embedment depth, water table height, or settlement problems.
2. For soils classified as CH or MH, without
either torque probe values or blow count test results, selected anchors must be
rated for a 4B soil.
3. The torque
test probe is a devise for measuring the torque value of soils to assist in
evaluating the holding capacity of the soil in which the ground anchor is
placed. The shaft must be of suitable length for the full depth of the ground
anchor.
4. The torque value is a
measure of the load resistance provided by the soil when subject to the turning
or twisting force of the probe.
5.
Less than 175.
6. More than
550.
7. Refer to 4781-6-03(B)(5).
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(4) The pocket penetrometer and ground auger
torque tests shall be completed in accordance with proper test procedures and
under proper testing conditions for use with auger style ground anchors;
or
(5) If the soil appears to be
composed of peat, organic clays, or uncompacted fill, or appears to have
unusual conditions, a registered professional geologist, registered
professional engineer, or registered architect must determine the soil
classification and maximum allowable soil bearing capacity.
(C) Site drainage.
(1) Purpose. Drainage shall be provided to
direct surface water away from the home and to prevent water build-up under the
home
, and all vegetation shall be removed from
the underneath of the
manufactured
home.
(2) The home
site shall be
graded as shown in figure 2A of
rule 4781-6-02.2 of the Administrative Code
this rule, or
other methods, such as a
drain tile and automatic sump pump system, shall be
provided to remove any water that may collect under the home.
(3) All drainage shall be diverted away from
the home and shall slope a minimum of one-half inch per foot away from the
foundation for the first ten feet. Where property lines, walls, slopes, or
other physical conditions prohibit this slope, the site shall be provided with
drains or swales or otherwise graded to drain water away from the
structure.
(4) Sloped site
considerations. The home, where sited, shall be protected from surface runoff
from the surrounding area.
(5)
Refer to paragraph (B)(3) of rule
4781-6-
02.9
4781-6- 03.9 of the Administrative
Code regarding the use of drainage structures to
drain surface runoff.
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(6)
Gutters and downspouts. If gutters and downspouts are installed, the runoff
shall be directed a minimum of eighteen inches away from the home.
(7) Prohibited drainage. Roof drains and
downspouts shall not be connected to the foundation system. They shall be
independent and not interconnected.
(8) Concrete and masonry foundations. Drains
shall be provided around all concrete or masonry foundations that retain earth
and enclose habitable or usable spaces located below
grade or unused spaces
which
that are
in wet areas. Drainage tiles, gravel or crushed stone drains, perforated
pipe
, or other approved systems or materials
shall be installed below the area to be protected and shall discharge by
gravity or mechanical means to
drain away from the home or into an approved
drainage system. A
drainage system is not required when the
foundation is
installed on well-drained ground or sand-gravel mixture soils according to
standard soils classification. An additional interior
drainage system may be
required in especially wet areas.
(9) Concrete and masonry
foundation
damp-proofing.
Foundation walls that retain earth and enclose habitable or
useable spaces located below
grade or unused spaces
which
that are in wet
areas shall be damp-proofed from the top of the
footing to the finished
grade.
Except, a
foundation shall not be required to be damp-proofed where a
supplemental interior
foundation drainage system is tied to a sump
pump.
(10) Where a concrete or
masonry wall is used, the crawlspace or basement slabs shall have a foundation
drain that shall be separate from the perimeter drain until the point of
discharge by gravity or mechanical means into an approved drainage
system.
(D) Ground
moisture control.
(1) Vapor retarder. If the
space under the home is to be enclosed with solid skirting or other solid
materials, a vapor retarder shall be installed on the ground, to cover the
ground under the home. If the space under the home is to be enclosed with
vented perforated skirting or other perforated materials, vapor retarder is not
required.
(2) Vapor retarder
material. A minimum of six mil polyethylene sheathing or its equivalent shall
be used.
(3) Proper
installation.
(a) The entire area under the home shall be
covered with the vapor retarder as noted in this rule except for areas under
open porches, decks, and open recessed entries. Joints in the vapor retarder
shall be overlapped at least twelve inches and sealed.
(b) The vapor retarder may be placed directly
beneath footings, or otherwise installed around or over footings placed at
grade, and around anchors or other obstructions.
(c) Any voids or tears in the vapor retarder
shall be repaired.
(d) Where a
masonry exterior perimeter wall is installed, two inches of crushed stone,
clean washed gravel
, or
its
their
equivalent shall cover the vapor barrier or be covered by the vapor
barrier.
Notes
Ohio Admin. Code 4781-6-03.2
Effective:
1/20/2020
Five Year Review (FYR) Dates:
8/27/2019 and
01/20/2025
Promulgated
Under:
119.03
Statutory Authority:
4781.04,
4781.14
Rule Amplifies:
4781.04,
4781.14
Prior Effective Dates: 09/15/2006, 01/01/2010, 06/02/2011,
12/01/2012
