(A) General. All requirements of the Land Development Code of the town regarding encroachments in streets, yards and courts shall be obeyed, and required setbacks from property lines and public roads shall be met.
(B) Fire separation distances. The distance a home must be sited from other structures depends on its fire-resistance rating. No manufactured home may be installed closer than ten feet from another primary structure.
(C) Bearing capacity. Test the bearing capacity of the soil in accordance with this division (C) before designing the foundation. If the soil cannot be tested, but its type can be identified, use the foundation bearing pressures shown in Table 3-1 as a guide. If the soil cannot be identified, use a bearing capacity of 1,000 pounds per square foot. Under unusual conditions, or if the soil appears to be composed of peat or un-compacted fill, or has expansive characteristics, consult a local geologist, engineer or architect.
(D) Soil. Use a pocket penetrometer or other methods acceptable to the town. The proper penetrometer reading must be taken after removing all organic material to undisturbed earth, at the foundation bearing level. The installer is responsible for documenting soil types and bearing capacities.
(E) Gutters and downspouts. When gutters and/or downspouts are installed, direct the runoff away from the home. The use of splash blocks and downspout extensions will enhance drainage away from the home.
(F) Foundation requirements. All exterior walls, marriage walls, marriage wall posts, columns and piers must be supported on an acceptable foundation system that must be of sufficient design to support safely the loads imposed, as determined by the character of the soil.
(G) Height above grade. Foundation wall shall extend at least six inches above the finished grade adjacent to the foundation at all points.
(H) Minimum foundation wall and wall footing thickness. If masonry or concrete construction is used, the minimum foundation wall width shall be six inches. The minimum reinforced concrete footing thickness shall be three and one-half inches or one and one-half times the length of the footing projection from the foundation wall, whichever is greater.
(I) Crawl space requirements (basementless spaces).
(1) Height requirement. Ground level must be at last 18 inches below the bottom of wood floor joists and 12 inches below the bottom of the chassis beams. (See § 152.004 of this chapter.)
(2) Interior vs. exterior ground level. The interior ground level must be above the outside finish grade with a minimum 2% slope to the exterior unless:
(a) Adequate gravity drainage to a positive outfall is provided;
(b) A professional engineer or architect certifies the permeability of the soil and the water table is such that water will not collect in the crawl space; or
(c) A full perimeter foundation drain and sump pit are provided.
(3) Configuration. Select manufactured pier heights so that the adjustable risers do not extend more than two inches when finally positioned. All piers must rest on footings (see § 152.004 of this chapter) that extend below the frost line (see § 152.004 of this chapter for exemptions to placement) and are placed on either undisturbed soil or compacted fill except for interior heated areas which may bear above frost line on undisturbed soil or compacted fill.
(4) Design procedures. Pier height is to be measured from the top of the footing.
(5) Other materials. Other materials approved for footings may be used when approved by local authorities if they provide equal load-bearing capacity and resistance to decay. Examples include: one-half inch maximum crushed stone; three-eights inch or three-fourths graduated gravel; coarse sand, with no grains smaller than one-sixteenth inch, placed so it provides a soil-bearing capacity of at least 3,000 pounds per square foot; approved ANS footings.
(J) Permanent foundation. See Permanent Foundations Guide for Manufactured Housing.
(K) Severe wind areas. Consult the authority having jurisdiction or a professional engineer or architect.
(L) (Table 5-1) normal home installations (single - or - multi-section homes).
(1) Piers-ground anchors. The manufactured home rests on piers of concrete block; formed-in- place concrete; permanent wood; or steel pedestals on permanent wood, crushed stone, approved ABS or concrete footers. The ground anchors are embedded at an angle in the soil to act as dead-men to resist the horizontal and vertical wind forces. Straps are tied to the frame, with or without over-the-top straps.
(2) Duct-work cross-overs. Clamp the flexible air conditioning and/or heating ducts to the sleeves projecting through the bottom covering, seal the ducts’ adjustable collars with several wrappings of duct tape and suspend/support them above the ground. (See Figure 5-1.)
(3) Number and location of anchors.
(a) The home must be anchored to the ground in order to resist overturning and lateral movement (sliding) of the home caused by forces imposed by the wind. The tie-down anchoring system described in this section is one acceptable method of anchoring the home to withstand its wind load.
(b) Unless otherwise noted, all tie-down and anchoring instructions are for homes with roof pitches which do not exceed 20 degrees (4.3 inches in 12 inches).
(c) The tie-down anchoring devices shall be certified by a registered state professional engineer, architect or a nationally recognized laboratory. They must be capable of resisting an allowable working load equal to or exceeding 3,150 pounds and shall be capable of withstanding a 50% overload (4,725 pounds total) at an angle of 45 degrees from the vertical. Ground anchors must be installed as specified by the anchor manufacturer.
(d) Anchoring equipment exposed to weather shall have a resistance to weather deterioration at least equivalent to that provided by a coat of zinc on steel of not less than 0.3 ounces per square foot of surface coated. Slit or cut edges of zinc-coated strapping do not need to be zinc-coated.
(e) Straps shall be Type 1, Finish B, Grade 1, steel strapping, one and one-fourth inches wide and 0.035 inches in thickness, certified by a registered professional engineer or architect, or listed as conforming with ASTM Standard Specification D3953-91, Standard Specification for Strapping, Flat Steel and Seals.
(f) The home must be in its final position with sections fastened together prior to installing tie-down equipment.
(4) Ground anchors.
(a) Before ground anchor installation, determine that the anchors will not be close to any underground utility lines.
(b) The ground anchor spacing and installation method were developed by the Manufactured Housing Research Alliance.
(c) Ground anchors shall be installed in accordance with the manufacturer’s written instructions. The following is one example: Install the anchors at the locations selected from Table D when the home manufacturer’s installation instructions are not available.
(d) Steps for proper ground anchor installation. These steps must be followed to use Table D:
1. Place the anchors approximately four inches to the inside of the exterior wall line of the home or a sufficient distance to avoid interference with the skirting. (See diagram.)
2. Hold the Anchor at an angle of approximately 15 degrees off of vertical so that the head of the anchor is just outside the sidewall. (See diagram.)
3. Install the anchor to a depth of approximately one-third the anchor length.
4. Place a stabilizer plate (all lateral loaded ground anchor must have stabilizer plates) of the size indicated on the chart to the inside of the anchor shaft (side of shaft toward center of house) and two inches from the shaft. (See diagram.)
5. Drive the stabilizer plate into the ground until the top of the plate is flush with the surface of the ground.
6. Install the anchor to its full depth/length.
7. Attach the anchor head to the chassis main rail with approved strapping and connection hardware in accordance with the strap manufacturer’s instructions.
8. Pretension the anchor by pulling it up to the stabilizer plate. Pull the anchor approximately one-half inch more while it is in contact with the plate using the strap and take-up bolt to move the anchor head.
9. After all anchors have been installed and pre-tensioned, recheck all anchor straps to assure that they are tight and that the anchor shafts have remained in contact with the stabilizer plate.
(e) Important notes about the anchor spacing selector.
1. For homes with eight-foot sidewalls, reduce the recommended anchor spacing by one-half foot.
2. Do not use this chart for homes with roof slopes greater than 20 degrees (approximately 4 in 12).
3. Anchors are required within two feet of each end wall.
(Prior Code, § 515.13) (Ord. 464, passed 8-2-2002; Ord. 584, passed 10-1-2015)