Anchoring Standards

PURPOSE: This rule applies to the anchoring of any manufactured home purchased or relocated on or after the effective date of this rule. This rule shall not be applicable to any manufactured home which has previously been anchored at its existing location and which has not been relocated subsequent to the effective date of this rule. (1) Definitions. The following definitions, as well as those set out in section 700.010, RSMo apply to this chapter: (A) Anchor means any device designed to transfer wind loads imposed on a manufactured home to the ground; (B) Anchoring equipment means straps, seals, cables, turnbuckles, and tensioning devices, which are used to secure a manufactured home to anchors; (C) Anchoring systems means a combination of ties, anchoring equipment, and anchors that will, when properly designed and installed, resist overturning and lateral movement of the manufactured home from wind forces; (D) Classified soil means soil that has been evaluated through the use of a standard soil torque probe or other approved method to determine anchor-holding capacity; (E) Installed means the arrangement and assembly at the occupancy site of all portions of an anchoring system, in accordance with the manufacturer’s design, that renders the anchoring system fit for its intended use; (F) Stabilizing device means a lateral support device such as a steel plate or a concrete collar used in connection with an anchor to limit lateral movement of the anchor; (G) Tie means straps, cable, or securing devices used to connect the manufactured home to the anchor; and (H) Unclassified soil means soils that have not been evaluated to determine anchor-holding capacity. (2) Anchoring System. Each manufactured home installed after the effective date of the rule must be anchored in accordance with the minimum standards specified in the rule. At a minimum, each anchoring system must also meet or exceed the design wind load requirements for Wind Zone 1, as defined in 3280.305 in the Federal Manufactured Home Construction and Safety Standards. (3) Anchoring Equipment. (A) Load. Anchoring equipment, when installed, must be capable of resisting an allowable working load equal to or exceeding three thousand one hundred fifty (3,150) pounds and must be capable of withstanding a fifty percent (50%) overload (four thousand seven hundred twenty-five (4,725) pounds total) without failure of either the anchoring equipment or the attachment point on the manufactured home. (B) Resistance to Weather Deterioration. Anchoring equipment exposed to weathering shall have a coating that is resistant to weather deterioration at least equivalent to that provided by a coating of zinc on steel of not less than 0.30 ounces per square foot of surface (.0005 inch in thickness), and in accordance with the following: 1. Slit or cut edges of zinc-coated steel strapping do not need to be zinc coated; 2. Flat steel strapping shall be Type 1, Heavy Duty, Finish B, Grade 1, 1 1/4 inches wide and 0.035 inch in thickness, certified by a registered professional engineer as conforming with ASTM Standard Specification D3953-91, Standard Specification for strapping, flat steel, and seals; and 3. Seals shall be Class H, Heavy Duty, Finish B, Grade 1, for steel strapping, certified by the manufacturer as conforming with ASTM Standard Specification D3953-91. (C) Permanency of Connections. Anchoring equipment shall be designed and installed to prevent self-disconnection when ties are slack. (4) Tensioning Devices. Tensioning devices such as turnbuckles or yoke-type fasteners shall be ended with clevis or forged or welded eyes. (5) Ties. (A) Material. 1. Flat steel strapping and seals or other approved methods or materials shall be used for ties. All ties shall be fastened to anchors and drawn tight with turnbuckles or other adjustable tensioning devices or devices approved for use with the anchor. 2. Tie materials shall be either as described in (3)(B)2. of this standard or other approved material capable of resisting an allowable working load of three thousand one hundred fifty (3,150) pounds with no more than twelve percent (12%) elongation and shall withstand a fifty percent (50%) overload (four thousand seven hundred twenty-five (4,725) pounds total). (B) Attachment. 1. Ties shall connect the anchor and the main structural steel frame that runs lengthwise under the manufactured home. Ties shall not connect to steel outrigger or cross beams that fasten to and intersect the main structural frame. Tie-down straps shall be routed from the anchor to the top of the main structural steel frame. 2. Tie-down straps shall be attached to the anchor in accordance with the anchor manufacturer’s instructions. A permanently attached strap that has been cut off may be spliced, provided an approved splicing device is used. (C) Vertical Ties. Vertical ties are not required in Wind Zone 1, as defined in 3280.305 in the Federal Manufactured Home Construction and Safety Standards. (6) Anchors. (A) Each anchor, when installed in classified soil, must be capable of resisting a minimum allowable working load of three thousand one hundred fifty (3,150) pounds in the direction of the tie, plus a fifty percent (50%) overload (four thousand seven hundred twenty-five (4,725) pounds total) without failure. Failure shall be considered to have occurred when the head of the anchor moves more than two inches (2") vertically or three inches horizontally when pulled at an angle of between forty degrees (40°) and fifty degrees (50°) under a force of four thousand seven hundred twenty-five (4,725) pounds. (B) Each manufactured anchor shall be tested and installed in accordance with the terms of its specified testing procedures and the anchor manufacturer’s instructions. Each anchor shall be installed and pre-tensioned until it is flush with the stabilizer plate. The slotted bolt must have a minimum of four (4) wraps of the strap after installation. (C) Spacing and Location. 1. Classified soil. A. All anchors shall be installed at the intervals and in the locations specified by the manufactured home manufacturer’s installation instructions, and in the correct soil class for which they are approved. B. In the event that the manufacturer’s installation instructions are unavailable, all anchors shall be installed in accordance with Tables (A) through (C) of this standard included herein, and in the correct soil class for which they are approved. 2. Unclassified soil. All anchors installed in unclassified soil shall be in accordance with Tables (A) through (C) of this standard, included herein. A thirty-inch (30") double four-inch (4") helix anchor with a twelve-inch (12") stabilizer shall be used in unclassified soil. 3. Spacing. A. Spacing shall be as even as practicable along the entire length of the home with the first anchor on each end no more than two feet (2') from the end of the home. (D) Soil Testing. A determination for soil classification should be made at each anchor location through the use of a standard torque probe, as described in ASTM Standard D2573-94, or equivalent method. If no soil classification test is performed for the anchor location, then the soil at the location shall be considered as unclassified. (7) Diagonal Tie-Down Strap Spacing. Strap spacing for anchors is illustrated in the following tables. (A) Tables (A) through (C), included herein, illustrate the strap spacing for single section and multi-section homes with anchors located in classified and unclassified soils. 1. Note that the maximum vertical distance is measured from the anchor head to the top of the I-beam (i.e., bottom of the floor). 2. The maximum distance to the first tie-down strap at each end of the home shall be two feet (2'0"). 3. Strap spacing calculations are based on the fact that single disk anchors and double disk anchors have the same holding capacity if installed in accordance with the anchor manufacturer’s installation instructions and in the proper soil classification. 4. Anchors shall be installed just inside the skirting line in order to maintain the angles identified in each table. 5. Anchor strap attachments to the home must be in accordance with the anchor manufacturer’s methods. (B) Tables (D) and (E), included herein, illustrate the criss-cross strapping system for elevated single and multi-section homes (or portion thereof) to be used in lieu of diagonal tie-down strap spacing tables; and (C) Table (F), included herein, illustrates approved methods of ground anchor installation. (8) Spacing For Federal Manufactured Home Construction and Safety Standards Wind Zone 1 Conditions. (A) If the floor width is one hundred sixtysix inches (166") (typical fourteen (14)-wide), with I-beam spacing ninety-five inches (95") or greater center to center and the distance from the top of the footer to the top of the Ibeam is no higher than sixty-four inches (64"), anchors shall be spaced eight feet (8') apart for classified soil, or five feet (5') apart for unclassified soil. (B) If the floor width is one hundred fortyone inches (141") (typical twelve (12)-wide), with I-beam spacing seventy-five and onehalf inches (75.5") or greater center to center and the distance from the top of the footer to the top of the I-beam is no higher than fiftytwo inches (52"), anchors shall be spaced six feet (6') apart for classified soil, or four feet (4') apart for unclassified soil. (C) Anchors must be installed just inside the skirting line, or as close to the skirting line as possible. AUTHORITY: section 700.076, RSMo 2000*. This rule originally filed as 4 CSR 240124.045. Original rule filed June 12, 2001, effective Jan. 30, 2002. Moved to 20 CSR 4240-124.045, effective Aug. 28, 2019. *Original authority: 700.076, RSMo 1976, amended 1978, 1982.