PDFWAC 51-51-0507

Section R507—Decks.

TABLE R507.3.1
MINIMUM FOOTING SIZE FOR DECKS
LIVE OR GROUND SNOW LOAD
(psf)
TRIBUTARY AREA
(sq.ft.)
LOAD-BEARING VALUE OF SOILSacd (psf)
1500e
2000e
≥ 3000e
Side of a square footing
(inches)
Diameter of a round footing
(inches)
Thicknessf
(inches)
Side of a square footing
(inches)
Diameter of a round footing
(inches)
Thicknessf
(inches)
Side of a square footing
(inches)
Diameter of a round footing
(inches)
Thicknessf
(inches)
60 Live or 70 Ground Snow Load
5
7
8
6
7
8
6
7
8
6
20
12
14
6
11
13
6
9
10
6
40
18
20
6
15
17
6
12
14
6
60
21
24
8
19
21
6
15
17
6
80
25
28
9
21
24
8
18
20
6
100
28
31
11
24
27
9
20
22
7
120
30
34
12
26
30
10
21
24
8
140
33
37
13
28
32
11
23
26
9
160
35
40
15
30
34
12
25
28
9
For SI: 1 inch = 25.4 mm, 1 square foot = 0.0929 m2, 1 pound per square foot = 0.0479 kPa.
a.
Interpolation permitted, extrapolation not permitted.
b.
Reserved.
c.
Footing dimensions shall allow complete bearing of the post.
d.
If the support is a brick or CMU pier, the footing shall have a minimum 2-inch projection on all sides.
e.
Area, in square feet, of deck surface supported by post and footings.
f.
Minimum thickness shall only apply to plain concrete footings,
R507.4 Deck posts. For single-level decks, wood post size shall be in accordace with Table R507.4.
TABLE R507.4
DECK POST HEIGHT
 
 
 
TRIBUTARY AREAg,h (sq. ft.)
 
 
 
20
40
60
80
100
120
140
160
LOADSb (psf)
POST SPECIESc
POST SIZEd
MAXIMUM DECK POST HEIGHTa (feet-inches)
60 Live Load,
≤60 Ground Snow Load
Douglas Fire, Hem-fire, SPFe
4 x 4
14-0
10-10
8-7
7-0
5-8
4-1
NP
NP
4 x 6
14-0
13-10
11-1
9-5
8-2
7-3
6-4
5-4
6 x 6
14-0
14-0
14-0
14-0
14-0
13-3
10-9
6-11
8 x 8
14-0
14-0
14-0
14-0
14-0
14-0
14-0
14-0
Redwoodf, Western Cedarsf, Ponderosa Pinef, Red Pinef
4 x 4
14-0
10-3
7-0
NP
NP
NP
NP
NP
4 x 6
14-0
13-6
10-6
8-4
5-10
NP
NP
NP
6 x 6
14-0
14-0
14-0
14-0
11-11
NP
NP
NP
8 x 8
14-0
14-0
14-0
14-0
14-0
14-0
14-0
14-0
70 Ground Snow Load
Douglas Fire, Hem-fire, SPFe
4 x 4
14-0
10-1
7-11
6-6
5-3
3-7
NP
NP
4 x 6
14-0
12-10
10-3
8-9
7-7
6-8
5-10
4-11
6 x 6
14-0
14-0
14-0
14-0
14-0
12-2
9-9
5-9
8 x 8
14-0
14-0
14-0
14-0
14-0
14-0
14-0
14-0
Redwoodf, Western Cedarsf, Ponderosa Pinef, Red Pinef
4 x 4
14-0
9-5
6-5
NP
NP
NP
NP
NP
4 x 6
14-0
12-6
9-8
7-7
5-3
NP
NP
NP
6 x 6
14-0
14-0
14-0
14-0
10-8
NP
NP
NP
8 x 8
14-0
14-0
14-0
14-0
14-0
14-0
14-0
14-0
For SI: 1 inch = 25.4 mm, 1 foot = 304.8 mm, 1 square foot = 0.0929 m2, 1 pound per square foot = 0.0479 kPa, NP = Not permitted.
a.
Measured from the underside of the beam to top of footing or pier.
b.
10 psf dead load. Snow load not assumed to be concurrent with live load.
c.
No. 2 grade, wet service factor included.
d.
Notched deck posts shall be sized to accommodate beam size in accordance with Section R507.5.2.
e.
Includes incising factor.
f.
Incising factor not included.
g.
Area, in square feet, of deck surface supported by post and footing.
h.
Interpolation permitted. Extrapolation not permitted.
R507.5 Deck beams. Maximum allowable spans for wood deck beams, as shown in Figure R507.5, shall be in accordance with Table R507.5. Beam plies shall be fastened together with two rows of 10d (3-inch × 0.128-inch) nails minimum at 16 inches (406 mm) on center along each edge. Beams shall be permitted to cantilever at each end up to one-fourth of the actual beam span. Deck beams of other materials shall be permitted where designed in accordance with accepted engineering practices.
Tables R507.5(1) through R507.5(4) are not adopted.
TABLE R507.5
MAXIMUM DECK BEAM SPAN - 60 PSF LIVE LOAD or
70 PSF GROUND SNOW LOADc
BEAM SPECIESd
BEAM SIZEe
EFFECTIVE DECK JOIST SPAN LENGTHa,i
(feet)
6
8
10
12
14
16
18
 
MAXIMUM DECK BEAM SPAN LENGTHa,b,f
(feet-inches)
Douglas fir-larchg,
Hem-firg,
Spruce-pine-firg
1-2×6
3-5
2-10
2-5
2-2
2-0
1-10
1-9
1-2×8
4-7
3-8
3-2
2-10
2-7
2-5
2-4
1-2×10
5-8
4-9
4-1
3-8
3-4
3-1
2-11
1-2×12
6-7
5-8
5-0
4-6
4-1
3-10
3-7
2-2×6
5-2
4-6
4-0
3-5
3-1
2-10
2-7
2-2×8
6-11
6-0
5-3
4-7
4-1
3-8
3-5
2-2×10
8-5
7-4
6-6
5-10
5-2
4-9
4-5
2-2×12
9-10
8-6
7-7
6-11
6-4
5-9
5-4
3-2×6
6-6
5-7
5-0
4-7
4-2
3-9
3-5
3-2×8
8-8
7-6
6-8
6-1
5-6
5-0
4-7
3-2×10
10-7
9-2
8-2
7-6
6-11
6-4
5-10
3-2×12
12-4
10-8
9-7
8-9
8-1
7-7
7-1
Redwoodh, Western Cedarsh, Ponderosa Pineh, Red Pineh
1-2×6
3-6
2-11
2-6
2-3
2-0
1-11
1-9
1-2×8
4-6
3-10
3-3
2-11
2-8
2-6
2-4
1-2×10
5-6
4-9
4-2
3-9
3-5
3-2
3-0
1-2×12
6-4
5-6
4-11
4-6
4-2
3-11
3-8
2-2×6
5-3
4-7
4-1
3-6
3-2
2-11
2-8
2-2×8
6-8
5-9
5-2
4-8
4-2
3-10
3-6
2-2×10
8-2
7-1
6-4
5-9
5-4
4-10
4-6
2-2×12
9-5
8-2
7-4
6-8
6-2
5-9
5-5
3-2×6
6-4
5-8
5-1
4-8
4-3
3-10
3-6
3-2×8
8-4
7-3
6-5
5-11
5-5
5-1
4-8
3-2×10
10-2
8-10
7-11
7-2
6-8
6-3
5-11
3-2×12
11-10
10-3
9-2
8-4
7-9
7-3
6-10
For SI: 1 inch = 25.4 mm, 1 foot = 304.8 mm, 1 pound per square foot = 0.0479 kPa, 1 pound = 0.454 kg.
a.
Interpolation allowed. Extrapolation is not allowed.
b.
Beams supporting a single span of joists with or without cantilever.
c.
Dead load = 10 psf, L/Δ = 360 at mainspan, L/Δ = 180 at cantilever. Snow load not assumed to be concurrent with live load.
d.
No. 2 grade, wet service factor included.
e.
Beam depth shall be equal to or greater than the depth of intersecting joist for a flush beam connection.
f.
Beam cantilevers are limited to the adjacent beam's span divided by 4.
g.
Includes incising factor.
h.
Incising factor not included.
i.
Deck joist span as shown in Figure R507.5.
j.
For calculation of effective joist span, the actual joist span length shall be multiplied by the joist span factor in accordance with Table R507.5(5).
R507.6 Deck joists. Maximum allowable spans for wood deck joists, as shown in Figure R507.6, shall be in accordance with Table R507.6. The maximum joist spacing shall be limited by the decking materials in accordance with Table R507.7.
TABLE R507.6
MAXIMUM DECK JOIST SPANS
LOADa
(psf)
JOIST
SPECIESb
JOIST SIZE
ALLOWABLE JOIST SPANb,c
(feet-inches)
MAXIMUM CANTILEVERd,f
(feet-inches)
Joist Spacing
(inches)
Adjacent Joist Back Spang
(feet)
12
16
24
4
6
8
10
12
14
16
18
60 Live Load or
70 Ground Snow Load
Douglas fir-larche, Hem-fire,
Spruce-pine-fire
2×6
7-11
7-1
5-9
1-0
1-6
NP
NP
NP
NP
NP
NP
2×8
10-5
9-5
7-8
1-0
1-6
2-0
2-1
NP
NP
NP
NP
2×10
13-3
11-6
9-5
1-0
1-6
2-0
2-6
2-8
NP
NP
NP
2×12
15-5
13-4
10-11
1-0
1-6
2-0
2-6
3-0
3-3
NP
NP
Redwoodf, Western Cedarsf, Ponderosa Pinef,
Red Pinef
2×6
7-4
6-8
5-10
1-0
1-4
NP
NP
NP
NP
NP
NP
2×8
9-8
8-10
7-4
1-0
1-6
1-11
NP
NP
NP
NP
NP
2×10
12-4
11-0
9-0
1-0
1-6
2-0
2-6
2-6
NP
NP
NP
2×12
14-9
12-9
10-5
1-0
1-6
2-0
2-6
3-0
3-0
NP
NP
For SI: 1 inch = 25.4 mm, 1 foot = 304.8 mm, 1 pound per square foot = 0.0479 kPa, 1 pound = 0.454 kg, NP = Not permitted.
a.
Dead load = 10 psf dead load. Snow load not assumed to be concurrent with live load.
b.
No. 2 grade, wet service factor included.
c.
L/Δ = 360 at main span.
d.
L/Δ = 180 at cantilever with 220-pound point load applied to end.
e.
Includes incising factor.
f.
Incising factor not included.
g.
Interpolation permitted. Extrapolation not permitted.
R507.9.1.2 Band joist details. Band joists supporting a ledger shall be a minimum 2-inch-nominal (51 mm), solid-sawn, spruce-pine-fir or better lumber or minimum 1-inch (25 mm) nominal engineered wood rim boards in accordance with Section R502.1.7. Band joists shall bear fully on the primary structure capable of supporting all required loads.
TABLE R507.9.1.3(1)
DECK LEDGER CONNECTION TO BAND JOIST
LOADc
(psf)
JOIST SPANa
(feet)
ON-CENTER SPACING OF FASTENERSb
(inches)
1/2-inch diameter lag screw
with
1/2-inch maximum sheathingd,e
1/2-inch diameter bolt
with
1/2-inch maximum sheathinge
1/2-inch diameter bolt
with
1-inch maximum sheathingf
60 Live Load or
70 Ground Snow Load
6
22
36
35
8
16
31
26
10
13
25
21
12
11
20
17
14
9
17
15
16
8
15
13
18
7
13
11
For SI: 1 inch = 25.4 mm, 1 foot = 304.8 mm, 1 pound per square foot = 0.0479 kPa.
a.
Interpolation permitted. Extrapolation is not permitted.
b.
Ledgers shall be flashed in accordance with Section R703.4 to prevent water from contacting the house band joist.
c.
Dead load = 10 psf. Snow load shall not be assumed to act concurrently with live load.
d.
The tip of the lag screw shall fully extend beyond the inside face of the band joist.
e.
Sheathing shall be wood structural panel or solid sawn lumber.
f.
Sheathing shall be permitted to be wood structural panel, gypsum board, fiberboard, lumber or foam sheathing. Up to 1/2-inch thickness of stacked washers shall be permitted to substitute for up to 1/2 inch of allowable sheathing thickness where combined with wood structural panel or lumber sheathing.
R507.9.2 Deck lateral load connections. Lateral loads shall be transferred to the ground or to a structure capable of transmitting them to the ground. Where the lateral load connection is provided in accordance with Figure R507.9.2(1), hold-down tension devices shall be installed in not less than two locations per deck, within 24 inches of each end of the deck. Each device shall have an allowable stress design capacity of not less than 1500 pounds (6672 N). Where the lateral load connections are provided in accordance with Figure R507.9.2(2), the hold-down tension devices shall be installed in not less than four locations per deck, and each device shall have an allowable stress design capacity of not less than 750 pounds (3336 N).
EXCEPTION:
Decks not more than 30 inches above grade at any point may be unattached.
TABLE R507.9.1.3(2)
PLACEMENT OF LAG SCREWS AND BOLTS IN DECK LEDGERS AND BAND JOISTS
MINIMUM END AND EDGE DISTANCES AND SPACING
BETWEEN ROWS
 
TOP
EDGE
BOTTOM
EDGE
ENDS
ROW
SPACING
Ledgera
2 inchesd
3/4 inch
2 inchesb
1 5/8 inchesb
Band joistc
3/4 inch
2 inchese
2 inchesb
1 5/8 inchesb
For SI:
1 inch = 25.4 mm.
a
Lag screws or bolts shall be staggered from the top to the bottom along the horizontal run of the deck ledger in accordance with Figure R507.9.1.3(1).
b
Maximum 5 inches.
c
For engineered rim joists, the manufacturer's recommendations shall govern.
d
The minimum distance from bottom row of lag screws or bolts to the top edge of the ledger shall be in accordance with Figure R507.9.1.3(1).
e
The 2 inches may be reduced to 3/4 inch when the band joist is directly supported by a mudsill, a header or by double top wall plates.
[Statutory Authority: RCW 19.27.031 and 19.27.074. WSR 23-23-104, § 51-51-0507, filed 11/15/23, effective 3/16/24; WSR 23-02-058, 23-12-104, and 23-20-024, § 51-51-0507, filed 1/3/23, 6/7/23, and 9/25/23, effective 3/15/24; WSR 21-16-006, § 51-51-0507, filed 7/22/21, effective 8/22/21; WSR 20-21-041, § 51-51-0507, filed 10/13/20, effective 11/13/20; WSR 20-03-023, § 51-51-0507, filed 1/6/20, effective 7/1/20; WSR 16-03-025, § 51-51-0507, filed 1/11/16, effective 7/1/16. Statutory Authority: RCW 19.27.031 and chapters 19.27 and 34.05 RCW. WSR 13-04-068, § 51-51-0507, filed 2/1/13, effective 7/1/13.]