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.)
Table 4
SECTION 6: JOIST - TO - BEAM CONNECTIONS
Joists must be attached to beams in accordance with Figure 8 and all of the following:
1.
Use Options 1 or 2 if joists bear on a dropped beam.
2. Use Option 3 if joists bear at a flush beam; see section 7 for hanger requirements.
3. Mechanical fasteners or hurricane clips must have a minimum capacity of 100 pounds in both uplift and lateral directions. Installation must be in accordance with the manufacturer's instructions.
Figure 8
JOIST-TO-BEAM CONNECTIONS
SECTION 7: JOIST HANGERS
Joist hangers must comply with all of the following:
1.
The joist-hanger depth (d, as shown in Figure 9) must be at least 60 percent of the joist depth.
2. The manufactured width of the joist hanger must accommodate the number of plies being carried.
3. Do not bend hanger flanges to accommodate field conditions.
4.
For joist hangers that are fastened to a ledger board, screws which are recommended by the manufacturer must be used. All other fasteners are permitted to be nails. The number of fasteners and the manner in which they are used must be as specified by the manufacturer.
5. Use joist hangers with inside flanges if clearances to the edge of the beam or ledger board dictate.
6. Clip-angles or brackets used to support framing members in lieu of joist hangers are prohibited.
7. Joists must not frame in from both sides of the same beam. Engineering analysis is needed if more beams are needed than are shown in Figures 5 to 7.
8.
Each joist hanger must have the minimum capacity listed in Table 5.
Figure 9
JOIST HANGERS
Table 5
JOIST HANGER DOWNLOAD
SECTION 8: LEDGER ATTACHMENTS
General requirements. Ledger boards must be attached to the existing house in accordance with all of the following and section 9. Compliance is critical to ensure the safety and structural stability of your deck.
1.
The ledger-board depth must be greater than or equal to the depth of the deck joists, but not less than a 2”x8”.
2.
The ledger board must be attached in accordance with one of the conditions shown in Figures 11 through 13 – except if metal-plate-connected wood floor trusses were used in the house, see the text below for manufactured wood trusses.
3.
The existing band board on the house must be capable of supporting the deck. If this cannot be verified or if existing conditions differ from the details here, then a free-standing deck or an engineered design is required.
4.
The top of the ledger board and the top of the deck joists must be at the same elevation.
Wood I-joists. Many homes are constructed with wood I-joists, as shown in Figure 10. Rather than utilize a 2x band board, these systems are often constructed with a minimum 1-inch-thick engineered wood product
(EWP) band board capable of supporting a deck. If a minimum 1-inch EWP or 2x band board is not present, then a free-standing deck is required, as addressed in section 10.
