-4: Anchor Tie Down Spacing and Sizes

-4: Anchor Tie Down Spacing and Sizes The following specifications are the minimum standards for all tie down spacing and sizes. A. Wherever feasible, over-the-top tie down straps shall be attached to the anchor head tie down strap tensioning bolts at the anchor located directly beneath them. B. All vertical side wall and shear wall tie down brackets existing on the home must be properly strapped and anchored. Any vertical side wall brackets not used for installing anchors and straps for the proper installation of the home must have manufacturers documentation that excludes these brackets from use. C. Vertical side wall brackets which are not required to have anchor and strap installed are not to be folded up or compromised in any manner. D. Figure 22 shows the use of a radius clip (made from a short piece of frame strap) to protect the strap loop that passes through the slot in the side wall bracket. Figure 23 shows an alternate method (looped)for installing the anchor straps to a vertical side wall bracket. The open end of the strap (as shown in Figure 23) must not exceed six (6) inches in length. Any length of the open end of the strap exceeding the 6 inches will require the installation of a crimp seal on the open-end strap crimped to the vertical tie down strap. Figure 22. Use of a radius clip inside vertical sidewall and shear wall bracket slots. Figure 23. Alternate (looped) method for installing anchor straps in vertical sidewall brackets. E. On all new factory-built homes, any other method of attaching tie down straps to the wall bracket (looped) will require approval by the manufacturer and will require documentation submitted to the Division with the Property Locator/Certificate of Installation prior to the inspection. F. All tie down straps, cables and devices must be tested and approved by the manufacturer of the materials. All tie down straps shall be fastened to ground anchors and drawn tight with slotted tensioning bolts or other such tensioning devices listed with the ground anchor. Tie down straps must not be over-tightened. G . All tie down straps and devices must be attached to the Factory-Built home in accordance with the manufacturer’s instructions for the specific types of straps and devices. All tie- down straps and devices must be tested and approved. Straps must be type I, finished B, grade 1 steel strapping, 1 ¼” wide and 0.035” thick conforming with Federal Specifications strapping steel and seals FS QQ-S-781H-1974. H. Tie down straps shall not be kinked, bent or otherwise abnormally stressed when installed at an angle to the frame I-beam. Straps must not be in contact with the support piers. I. If the angle between the frame strap to the outer I-beam and the ground is greater than 45 degrees, a “Cross Strapping” method must be used as shown in Figure 24A and 24B. It requires an additional anchor tensioning bolt connected to a frame strap attached to the opposite outer frame I-beam for Wind Zone I installations (note dotted line in Figure 24A). Connect the strap to the top inside location on the opposite frame I-beam and wrap the strap completely around the I-beam. Position the strap directly over the lapped strap and in line with the anchor head. With the anchor and stabilizer device properly installed in the ground, insert the strap into the second slotted tensioning bolt in the anchor head, turning the bolt a minimum of 4-5 turns to remove slack from the frame strap. The first frame strap to the outer I-beam is to remain in place to provide additional tie down strength. If one of the tensioning bolts is connected to a vertical sidewall strap, typical for Wind Zone II or III installations (note dotted lines in Figure 24B), remove the strap from the near I-beam and install a longer strap to the opposing I beam. Figure 24A. “Cross Strapping” Wind Zone I Figure 24 B. “Cross Strapping” Wind Zone II and Wind Zone III Installation J. All tie down straps must be properly attached to the frame I-beam and the anchor head according to the manufacturer’s installation instruction and must be properly tensioned. Figures 25 and 26 illustrate the correct strap installation methods for use with double slot strap buckles and/or clips, respectively. According to manufacturer specifications, the winding of the strap on the anchor head bolt must contain a minimum of four to five complete turns. Figure 25. Installing Frame Tie Strap Using a Double Slot Strap Buckle Figure 26. Installing Frame Tie Strap Using a Hook Clip K. Splices in the anchor straps must be installed in accordance with the manufacturer’s instructions for straps and devices. If manufacturer instructions for splicing anchor straps are not available, the following instructions will apply. The ends of the straps must overlap to a minimum of six (6) inches and a maximum of twelve (12) inches. Two (2) crimp seals must be installed in the overlap of the strap ends and each crimp seal must be double crimped, as shown in Figure 27. Figure 27. Tie Down Strap Splice Details L. Tie down strap materials shall be capable of resisting an allowable working load of 3,150 lbs. with no more than 2% elongation and shall withstand a 50% overload [4,725 lbs. total]. Tie downs exposed to weathering shall be resistant to weathering deterioration at least equivalent to that provided by a coating of zinc on steel of not less than 0.30 oz. per square foot of surface coated. Type I, Class B, Grade I, steel strapping 1 1/4 inches wide and 0.035 inch thick, conforming to Federal Specifications QQ S 781 F, is judged to conform to this section. M. Materials used for tie down straps must terminate with D-rings bolts, or other fastening devices, which will not cause distortion of the band or reduce its breaking strength of 4,725 lb. Please note that tie down straps should be double wrapped (double looped) at top of the I- beam, returning to the anchor from this position, not from the bottom of the I-beam. N. Connection of the cable frame tie to the I-beam (or other shape) main structural frame member should be by a 5/8-inch drop forged closed eye bolted through a hole drilled in the center of the I-beam web. A washer, or equivalent, shall be used so that the beam is sufficiently reinforced around the hole. If steel strap ties are used, care should be exercised to ensure that minimum bending radius is adhered to so that the breaking strength of the strap is not reduced. O. Frame ties shall connect the anchor and the steel I-beam (or other shape) main structural frame member which run lengthwise under the Factory-Built home. Frame ties shall never be connected to any of the steel outrigger beams which fasten to and intersect the main I beam at right angles.