Washington Administrative Code › Title 51 - Enterprise Services, Department of (Building Code Council) › Chapter 51-51 - State Building Code adoption and amendment of the 2021 edition of the International Residential Code › Section 51-51-0507 - Section R507-Decks

Current through Register Vol. 24-14, July 15, 2024
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
[GREATER THAN EQUAL TO] 3000
							 psf
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
LOADSb
								(psf)
POST
							 SPECIESc
POST
							 SIZEd
TRIBUTARY
							 AREAg,h (sq. ft.)
20
40
60
80
100
120
140
160
MAXIMUM DECK POST
							 HEIGHTa (feet-inches)
60 Live Load, [LESS THAN IS EQUAL TO]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 LOAD
c
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/[DELTA] = 360 at mainspan, L/[DELTA] =
				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/[DELTA] = 360 at main span.
d. L/[DELTA] = 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 La g 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
				  chapters
				  19.27 and
				  34.05 RCW. 13-04-068, §
				  51-51-0507, filed 2/1/13, effective
				  7/1/13.