SPS 321.27(3)(a)1.1. Roofs shall withstand a pressure of at least 20 pounds per square foot acting upward normal to the roof surface.
SPS 321.27(3)(a)2. 2. Roof overhangs, eaves, canopies and cornices shall withstand an upward wind pressure of at least 20 pounds per square foot applied to the entire exposed area.
SPS 321.27(3)(b) (b) Anchorage.
SPS 321.27(3)(b)1.1. Roof framing members spanning more than 6 feet measured from the outermost edge of the roof shall be permanently fastened to the top plate of load bearing walls using engineered clips, straps or hangers.
SPS 321.27(3)(b)2. 2. Roof framing members spanning 6 feet or less measured from the outermost edge of the roof shall be permanently fastened to the top plate of load bearing walls using toe-nailing or engineered clips, straps or hangers.
SPS 321.27 Note Note: For information on toe nailing, see the fastener schedule table in the ch. SPS 325 Appendix A.
SPS 321.27(4) (4)Roof rafters.
SPS 321.27(4)(a)(a) General.
SPS 321.27(4)(a)1.1. Rafters shall be notched to fit the exterior wall plate and fastened to the wall.
SPS 321.27(4)(a)2. 2. Collar ties shall be installed on the upper third of every third pair of abutting roof rafters or every 48 inches, whichever is less.
SPS 321.27 Note Note: Collar ties are intended to provide stability to the roof at the ridge. Lateral restraint for the walls must be provided in accordance with sub. (2).
SPS 321.27(4)(b) (b) Ridge boards.
SPS 321.27(4)(b)1.1. Where rafters meet to form a ridge, the rafters shall be attached to a ridge board.
SPS 321.27(4)(b)2. 2. The ridge board shall have a depth at least equal to the length of the cut end of the rafter abutting it.
SPS 321.27(4)(b)3. 3. Where all rafters are placed directly opposite each other or are offset at the ridge board by less than the thickness of the rafter, the ridge board shall have a nominal thickness of at least 1 inch.
SPS 321.27(4)(b)4. 4. Where one or more rafters are offset at the ridge board by more than the thickness of the rafter, the ridge board shall have a nominal thickness of at least 2 inches.
SPS 321.27(4)(c) (c) Ridge beams. Rafters shall be attached to ridge beams using engineered clips, straps or hangers or the connection shall be designed through structural analysis.
SPS 321.27(4)(d) (d) Bearing. The required bearing for wood rafters shall be in accordance with the NDS adopted in Table 320.24-6m, except in no case shall the bearing be less than 1 1/2 inches on wood or metal or less than 3 inches on masonry or concrete.
SPS 321.27(4)(e) (e) Ladders.
SPS 321.27(4)(e)1.1. Overhangs at gable end walls of more than 12 inches shall be provided with ladders which extend into the structure a distance no less than the length of the overhang.
SPS 321.27(4)(e)2. 2. The ladders shall be fastened at the wall.
SPS 321.27(4)(e)3. 3. The interior end of each ladder shall be attached to a rafter or truss with a hanger.
SPS 321.27 Note Note: For the purposes of this section, a ladder is defined as a perpendicular projection extending beyond the face of the wall below.
SPS 321.27(5) (5)Ceiling joists.
SPS 321.27(5)(a)(a) Ceiling joists shall be nailed to exterior walls and to the ends of rafters.
SPS 321.27(5)(b) (b) Ends of ceiling joists shall be lapped at least 3 inches and be fastened either with 3-16d nails or in accordance with the floor joist requirements under s. SPS 321.22 (4) (a) 1. d.
SPS 321.27 Note Note: See the fastener table in the ch. SPS 325 Appendix A for a nailing schedule for ceiling joists.
SPS 321.27(5)(c) (c) Where ceiling joists are placed at right angles to the rafters, the lookout joist or ties shall be fastened to the parallel ceiling joists or rafters using engineered clips, straps or hangers or the connection shall be designed through structural analysis.
SPS 321.27(6) (6)Valley and hip rafters.
SPS 321.27(6)(a)(a) Valley rafters.
SPS 321.27(6)(a)1.1. Where no bearing is provided under valley rafters at the intersection of 2 roof areas, the valley rafters shall be doubled in thickness and shall be at least 2 inches deeper than the required common rafter to permit full bearing at the beveled end.
SPS 321.27(6)(a)2. 2. Where ridges are provided at different elevations, vertical support shall be provided for the interior end of the lower ridge board or ridge beam.
SPS 321.27(6)(b) (b) Hip rafters. Where no bearing is provided under hip rafters, the hip rafters shall be of the same thickness as common rafters and shall be at least 2 inches deeper than required to permit full contact with the jack rafter.
SPS 321.27(7) (7)Roof trusses.
SPS 321.27(7)(a)(a) Metal plate connected wood roof trusses shall be designed in accordance with TPI 1 and the NDS adopted under s. SPS 320.24.
SPS 321.27(7)(b) (b) Truss members shall not be cut, bored or notched, except as allowed under sub. (8) (d).
SPS 321.27(7)(c) (c) If connection is provided to stabilize a non-load bearing wall, a slotted expansion joint or clip shall be used.
SPS 321.27(8) (8)Notching and boring.
SPS 321.27(8)(a)(a) General.
SPS 321.27(8)(a)1.1. Notching and boring of beams or girders is prohibited unless determined through structural analysis.
SPS 321.27(8)(a)2. 2. Notching and boring of ceiling joists and rafters shall comply with pars. (b) and (c).
SPS 321.27(8)(b) (b) Notching.
SPS 321.27(8)(b)1.1. Notches located in the top or bottom of ceiling joists and rafters are prohibited from all of the following:
SPS 321.27(8)(b)1.a. a. Having a depth exceeding 1/6 the depth of the member.
SPS 321.27(8)(b)1.b. b. Having a length exceeding 1/3 the depth of the member.
SPS 321.27(8)(b)1.c. c. Being located in the middle 1/3 of the span of the member.
SPS 321.27(8)(b)2. 2. Where ceiling joists or rafters are notched at the ends, the notch may not exceed ¼ the depth of the member.
SPS 321.27(8)(b)3. 3. Bird mouth cuts may not exceed 1/3 the depth of the rafter unless the seat cut bears fully on the wall plate.
SPS 321.27(8)(c) (c) Boring.
SPS 321.27(8)(c)1.1. Holes bored within 2 inches of the top or bottom of ceiling joists or rafters may not be located in the middle 1/3 of the span of the member.
SPS 321.27(8)(c)2. 2. The diameter of a hole may not exceed 1/3 the depth of the member.
SPS 321.27(8)(c)3. 3. A hole may not be bored within 2 inches of a notch or another hole.
SPS 321.27(8)(c)4. 4. The distance between adjacent holes may not be less than the diameter of the larger hole.
SPS 321.27(8)(d) (d) Engineered wood products. Notching or boring of engineered wood products shall be done in accordance with the manufacturer's instructions provided those instructions were developed through structural analysis or product testing.
SPS 321.27(9) (9)Roof sheathing, boards and planking.
SPS 321.27(9)(a)(a) Structural sheathing. The allowable loads and spans for structural sheathing shall be in accordance with the grade stamp on the panel.
SPS 321.27(9)(b) (b) Roof boards.
SPS 321.27(9)(b)1.1. Where the rafter spacing is 24 inches on center or less, roof boards may be used that have a minimum thickness of 5/8-inch for solid sheathing and 3/4-inch for spaced sheathing.
SPS 321.27(9)(b)2. 2. Where the rafter spacing is greater than 24 inches on center, roof boards shall be tongue and groove, at least 1.5 inches thick.
SPS 321.27(9)(c) (c) Roof planks.
SPS 321.27(9)(c)1.1. Roof planks shall be tongue and groove or splined and at least 2 inches, nominal, in thickness.
SPS 321.27(9)(c)2. 2. Planks shall terminate over beams unless the joints are end matched.
SPS 321.27(9)(c)3. 3. The planks shall be laid so that no continuous line of joints will occur except at points of support.
SPS 321.27(9)(c)4. 4. Planks shall be nailed or fastened to each beam.
SPS 321.27 History History: Cr. Register, November, 1979, No. 287, eff. 6-1-80; am (3) (a), Register, January, 1989, No. 397, eff. 2-1-89; r. and recr. (1), am. (3) (a), Register, March, 1992, No. 435, eff. 4-1-92; r. and recr. (3) (a), Register, November, 1995, No. 479, eff. 12-1-95; r. and recr. (3) (a) 1. and 2. c., Register, January, 1999, No. 517, eff. 2-1-99; am. (3) (a) 1. a., Register, March, 2001, No. 543, eff. 4-1-01; CR 02-077: r. and recr. (3) (b) Register May 2003 No. 569, eff. 8-1-03; CR 08-043: r. and recr. Register March 2009 No. 639, eff. 4-1-09; correction in (1) (a), (c), (4) (d), (5) (b), (7) (a) made under s. 13.92 (4) (b) 7., Stats., Register December 2011 No. 672; CR 15-041: am. (4) (d) Register December 2015 No. 720, eff. 1-1-16.
SPS 321.28 SPS 321.28Weather protection for roofs.
SPS 321.28(1) (1)General.
SPS 321.28(1)(a)(a) All roofs shall be designed and constructed to assure drainage of water.
SPS 321.28(1)(b) (b) All fasteners shall be corrosion resistant.
SPS 321.28(2) (2)Underlayment for shingles. Underlayment consisting of number 15 asphalt-impregnated felt paper or equivalent or other type I material that shows no water transmission when tested in accordance with ASTM D 226 or ASTM D 4869 shall be provided under shingles.
SPS 321.28 Note Note: Underlayment materials meeting the requirements of ASTM D 1970 meet the performance requirements of this section.
SPS 321.28(3) (3)Asphalt shingles.
SPS 321.28(3)(a)(a) General.
SPS 321.28(3)(a)1.1. Shingles that have a self-sealing adhesive strip shall include a sealant which has an average bond strength of at least 1.5 pounds per 3.75 inches of shingle width, at 32°F.
SPS 321.28 Note Note: The department will accept results of testing conducted in accordance with an approved test method for verifying compliance with the sealant uplift resistance required in this paragraph. Information on the applicable test method may be obtained from the department.
SPS 321.28(3)(a)2. 2. Each shingle package shall be labeled by the manufacturer to indicate conformance to the applicable ASTM standard for each type of shingle or the exception in par. (c).
SPS 321.28(3)(a)3. 3. Shingles shall be installed in accordance with the manufacturer's recommendations.
SPS 321.28(3)(a)4. 4. Shingles shall have at least 4 fasteners per strip shingle or 2 fasteners per interlocking shingle, unless the manufacturer has other specifications.
SPS 321.28(3)(a)5. 5. Shingle head lap shall be at least 2 inches, unless the manufacturer has other specifications.
SPS 321.28(3)(a)6. 6. All fasteners for shingles shall be corrosion-resistant.
SPS 321.28 Note Note: See s. SPS 320.07 (62) for definitions of shingle terms.
SPS 321.28 Note Note: Section SPS 320.04 (2) requires compliance with all parts of this code, including these roofing provisions, for an alteration to any dwelling that is regulated under this code.
SPS 321.28(3)(c) (c) Fiberglass shingles. Fiberglass asphalt shingles shall conform to ASTM D 3462 except that laminated shingles shall have a tear strength of at least 1450 grams in each ply.
SPS 321.28(4) (4)Ice dam protection.
SPS 321.28(4)(a)(a) Shingled or shake roofs that extend over a heated area of a dwelling or attached garage and that have a slope of 4:12 or less shall be provided with ice dam protection in the form of sheet metal or a product labeled as meeting the requirements of ASTM D 1970.
SPS 321.28(4)(b) (b) The ice dam protection shall extend at least 30 inches up the roof slope from the roof edge and at least 12 inches up the roof slope beyond the inner face of the exterior wall.
SPS 321.28(5) (5)Other roof coverings. All roof coverings not otherwise addressed in this section shall be installed in accordance with the manufacturer's instructions or a national standard recognized by the department.
SPS 321.28(6) (6)Reroofing. New roof coverings may not be installed over existing roof coverings where any of the following conditions exist:
SPS 321.28(6)(a) (a) The existing roof or roof covering is water-soaked or has deteriorated such that it is inadequate as a base for additional roofing.
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Published under s. 35.93, Stats. Updated on the first day of each month. Entire code is always current. The Register date on each page is the date the chapter was last published.