Note: Galvanized steel is not compatible with stainless steel, which can result in rapid corrosion and structural failure.
Note: Hardware and fasteners that are beneath a hot tub which uses salt-water disinfection should be stainless steel, grade 304 or 316.
8. Every deck must have an electrical outlet along the perimeter of the deck and within 6.5 feet of the floor in accordance with NEC section 210.52(E)(3). See ch. SPS 316 of the Wisconsin Administrative Code for requirements about installing electrical wiring.
9. A deck constructed in accordance with these standards is not approved for concentrated loads that exceed 40 pounds per square foot (psf), such as from privacy screens, planters, built-in seating, hot tubs, stairs for multiple-level decks, or from snow-drift loads or sliding-snow loads. Engineering analysis is needed for these loads.
Note: See Appendix C for features of a deck which are somewhat uncommon or which have more complexity than is addressed in this Appendix – such as design values for joists consisting of western cedar or red pine, framing details around chimneys and bay windows, or ledger boards for metal-plate-connected wood floor trusses. Appendix C also includes reference material, such as more-detailed specifications for fasteners.
10. Specifications for fasteners and hardware. All nails must meet the requirements of ASTM F1667. Wood screws must meet the requirements of ANSI/ASME B18.6.1. Bolts and lag screws must meet the requirements of ANSI/ASME B18.2.1.
Fasteners to be hot-dipped galvanized must meet the requirements of ASTM A153, Standard Specification for Zinc Coating (Hot-Dip) on Iron and Steel Hardware, Class D for fasteners 3/8” diameter and smaller or Class C for fasteners with diameters over 3/8”.
Fasteners other than nails and timber rivets may consist of mechanically deposited zinc-coated steel with coating weights in accordance with ASTM B695, Class 55, minimum.
Hardware to be hot-dipped prior to fabrication must meet ASTM A653, Standard Specification for Steel Sheet, Zinc-Coated (Galvanized) or Zinc-Iron Alloy-Coated (Galvannealed) by the Hot-Dip Process, G-185 coating. Hardware to be hot-dipped galvanized after fabrication must meet ASTM A123, Specification for Zinc (Hot-Dip Galvanized) Coatings on Iron and Steel Products.
11. Safety glazing at decks shall be in accordance with the safety glazing requirements of the Uniform Dwelling Code (UDC).
SECTION 2: FOOTINGS, AND POST CONNECTIONS
Footings must comply with all of the following:
1.
Concrete must be used and must have a minimum compressive strength of 3,000 pounds per square inch.
2.
Footing size and thickness must be in accordance with Table 1. (See sections 4 and 5 for determining post spacing and joist length.)
3.
Post attachments must be in accordance with Figure 1 except expansion anchors are also permitted – and any instructions from the manufacturer of the anchor must be followed.
4.
Post anchors must include a 1-inch-minimum base plate. Steel plates are not required.
5.
Each post must bear directly over the middle one-third of a footing.
6.
Footings must bear on solid ground below the frost penetration level or at least 48 inches below finished grade, whichever is deeper. Bearing onto unprepared fill material, organic soil, alluvial soil, or mud is prohibited. The bearing capacity of the soil is presumed to be at least 2000 pounds per square foot (psf), and must be verified by a building inspector prior to placement of concrete.
7.
If the edge of a deck footing is closer than 5 feet to an existing house wall, the footing must bear at the same elevation as the existing footing for that wall.
8.
Construction of footings over utility lines or any service pipe is prohibited.
Note: Call the utility provider before digging.
Table 1
Figure 1
FOOTINGS
SECTION 3: POSTS AND POST-TO-BEAM CONNECTIONS
Posts must comply with all of the following:
1.
The post height, measured from the top of the footing to the underside of the beam, must be in accordance with Table 2.
Table 2
2. Any post supporting a beam splice must be a minimum of 6”x6”.
3. Beams must be attached to posts by the appropriate methods shown in Figure 2. Toe-nailing of beams to posts is prohibited.
4. Post caps, as shown in Figure 2, must be specifically designed for 2- or 3-ply beams and the post size used. Attachment must be in accordance with the manufacturer's instructions.
5. It is recommended that cut-ends of posts should be field-treated with a wood preservative. These preservatives can be found in the paint department of most hardware or home-center stores.
Figure 2
POST-TO-BEAM CONNECTIONS
SECTION 4: BEAMS
Beams must comply with all of the following:
1.
As shown in Figure 3, the beam-span length is measured between the centerlines of 2 adjacent posts and does not include the overhangs.
2. Beam size is determined using Table 3A or 3B. The depth of flush beams must be greater than or equal to the joist depth.
3. Beams may overhang past the center of the post up to one-fourth of the actual beam span, as shown in Figure 3.
4. Where multiple 2x members are used to assemble a beam, the plies of the beam must be fastened in accordance with Figure 4.
5. Pressure-preservative-treated glulam beams are permissible for spans longer than those shown in Table 3. However, a design and plan submission is required during the permit application process.
Figure 3
BEAM TYPES
Table 3A
MAXIMUM BEAM-SPAN LENGTH1 FOR DOUGLAS FIR/LARCH
3, HEM/FIR
3, SPRUCE/PINE/FIR (SPF)
3, WESTERN CEDAR, PONDEROSA PINE
4, AND RED PINE
4
- See PDF for table - See PDF for table
Table 3B
Figure 4
BEAM ASSEMBLY
SECTION 5: JOISTS
Joists must comply with all of the following:
1.
The joist-span length is measured between the centerline of bearing at each joist-span end and does not include the overhangs. Use Table 4 to determine the joist size based on span length and joist spacing. See section 12.4 for limits on joist spacing if the decking consists of a wood-plastic composite.
2. See Figures 5 through 7 for joist-span types.
3. Joists must bear at least 3 inches nominal onto beams, unless joist hangers are used in accordance with section 7.
4. Joists may overhang past the center of the beam up to one-fourth of the actual joist span.
5. Provide full-depth 2x blocking or bridging for 2”x10” or deeper joists at intervals not exceeding 8 feet – except the blocking can be reduced to 60% of the height if placed above a beam, for drainage purposes. Attach the blocking or bridging with (3)10d toe-nails at each end.
6. Attach a continuous rim joist as shown in Figures 5 and 7 unless blocking or bridging is provided for each joist at the beam where a joist overhang begins. Attach the rim joist to the end of each joist with (3)10d nails or (3)#10 by 3-inch wood screws.
Figure 5
JOISTS WITH DROPPED BEAM – DECK ATTACHED AT HOUSE
Figure 6
JOISTS WITH FLUSH BEAM – DECK ATTACHED AT HOUSE
Figure 7
(See section 10 for more information.)