Deck Joist & Beam Span Charts

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.

  1. Interpolation permitted. Extrapolation not permitted.
  2. Beams supporting a single span of joists with or without cantilever.
  3. Dead load = 10 psf, L/Δ = 360 at main span, L/Δ = 180 at cantilever. Snow load is not assumed to be concurrent with live load.
  4. No. 2 grade, wet service factor included.
  5. Beam depth shall be equal to or greater than the depth of intersecting joist for a flush beam connection.
  6. Beam cantilevers are limited to the adjacent beam’s span divided by 4.
  7. Includes incising factor.
  8. Incising factor not included.
  9. Deck joist span as shown in Figure R507.5.
  10. For calculation of effective deck joist span, the actual joist span length shall be multiplied by the joist span factor in accordance with Table R507.5(5).

MAXIMUM DECK BEAM SPAN—50 PSF GROUND SNOW LOAD c

BEAM SPECIES d BEAM SIZE e EFFECTIVE DECK JOIST SPAN LENGTH (feet) a, i, j
6′ 8′ 10′ 12′ 14′ 16′ 18′
MAXIMUM DECK BEAM SPAN LENGTH (feet-inches) a, b, f
Southern pine 1 – 2×6 4′6″ 3′11″ 3′6″ 3′2″ 2′11″ 2′9″ 2′7″
1 – 2×8 5′9″ 4′11″ 4′5″ 4′0″ 3′9″ 3′6″ 3′3″
1 – 2×10 6′9″ 5′10″ 5′3″ 4′9″ 4′5″ 4′2″ 3′11″
1 – 2×12 8′0″ 6′11″ 6′2″ 5′8″ 5′3″ 4′11″ 4′7″
2 – 2×6 6′8″ 5′9″ 5′2″ 4′9″ 4′4″ 4′1″ 3′10″
2 – 2×8 8′6″ 7′4″ 6′7″ 6′0″ 5′7″ 5′2″ 4′11″
2 – 2×10 10′1″ 8′9″ 7′10″ 7′1″ 6′7″ 6′2″ 5′10″
2 – 2×12 11′11″ 10′3″ 9′2″ 8′5″ 7′9″ 7′3″ 6′10″
3 – 2×6 7′11″ 7′2″ 6′6″ 5′11″ 5′6″ 5′1″ 4′10″
3 – 2×8 10′5″ 9′3″ 8′3″ 7′6″ 6′11″ 6′6″ 6′2″
3 – 2×10 12′8″ 10′11″ 9′9″ 8′11″ 8′3″ 7′9″ 7′3″
3 – 2×12 14′11″ 12′11″ 11′6″ 10′6″ 9′9″ 9′1″ 8′7″
Douglas fir-larch g

Western cedars h

Ponderosa pine h

For SI: 25.4 mm, 1 foot = 304.8 mm, 1 pound per square foot = 0.0479 kPa, 1 pound = 0.454 kg.

  1. Interpolation allowed. Extrapolation is not allowed.
  2. Beams supporting a single span of joists with or without cantilever.
  3. Dead load = 10 psf, L/Δ = 360 at main span, L/Δ = 180 at cantilever. Snow load not assumed to be concurrent with live load.
  4. No. 2 grade, wet service factor included.
  5. Beam depth shall be equal to or greater than the depth of intersecting joist for a flush beam connection.
  6. Beam cantilevers are limited to the adjacent beam’s span divided by 4.
  7. Includes incising factor.
  8. Incising factor not included.
  9. Deck joist span as shown in Figure R507.5.
  10. For calculation of effective deck joist span, the actual joist span length shall be multiplied by the joist span factor in accordance with Table R507.5(5).

MAXIMUM DECK BEAM SPAN—60 PSF GROUND SNOW LOAD c

BEAM SPECIES d BEAM SIZE e EFFECTIVE DECK JOIST SPAN LENGTH a, i, j (feet)
6′ 8′ 10′ 12′ 14′ 16′ 18′
MAXIMUM DECK BEAM SPAN LENGTH (feet-inches) a, b, f
Southern pine 1 – 2×6 4′2″ 3′7″ 3′3″ 2′11″ 2′9″ 2′6″ 2′5″
1 – 2×8 5′3″ 4′7″ 4′1″ 3′9″ 3′5″ 3′3″ 3′0″
1 – 2×10 6′3″ 5′5″ 4′10″ 4′5″ 4′1″ 3′10″ 3′7″
1 – 2×12 7′5″ 6′5″ 5′9″ 5′3″ 4′10″ 4′6″ 4′3″
2 – 2×6 6′2″ 5′4″ 4′9″ 4′4″ 4′0″ 3′9″ 3′7″
2 – 2×8 7′10″ 6′10″ 6′1″ 5′7″ 5′2″ 4′10″ 4′6″
2 – 2×10 9′4″ 8′1″ 7′3″ 6′7″ 6′1″ 5′8″ 5′4″
2 – 2×12 11′0″ 9′6″ 8′6″ 7′9″ 7′2″ 6′9″ 6′4″
3 – 2×6 7′5″ 6′9″ 6′0″ 5′6″ 5′1″ 4′9″ 4′6″
3 – 2×8 9′9″ 8′6″ 7′8″ 6′11″ 6′5″ 6′0″ 5′8″
3 – 2×10 11′8″ 10′2″ 9′1″ 8′3″ 7′8″ 7′2″ 6′9″
3 – 2×12 13′9″ 11′11″ 10′8″ 9′9″ 9′0″ 8′5″ 7′11″
Douglas fir-larch g

Western cedars h

Ponderosa pine h

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.

  1. Interpolation allowed. Extrapolation is not allowed.
  2. Beams supporting a single span of joists with or without cantilever.
  3. Dead load = 10 psf, L/Δ = 360 at main span, L/Δ = 180 at cantilever. Snow load not assumed to be concurrent with live load.
  4. No. 2 grade, wet service factor included.
  5. Beam depth shall be equal to or greater than the depth of intersecting joist for a flush beam connection.
  6. Beam cantilevers are limited to the adjacent beam’s span divided by 4.
  7. Includes incising factor.
  8. Incising factor not included.
  9. Deck joist span as shown in Figure R507.5.
  10. For calculation of effective deck joist span, the actual joist span length shall be multiplied by the joist span factor in accordance with Table R507.5(5).

MAXIMUM DECK BEAM SPAN—70 PSF GROUND SNOW LOAD c

BEAM SPECIES d BEAM SIZE e EFFECTIVE DECK JOIST SPAN LENGTH (feet) a, i, j
6′ 8′ 10′ 12′ 14′ 16′ 18′
MAXIMUM DECK BEAM SPAN LENGTH (feet-inches) a, b, f
Southern pine 1 – 2×6 3′11″ 3′4″ 3′0″ 2′9″ 2′6″ 2′4″ 2′3″
1 – 2×8 4′11″ 4′3″ 3′10″ 3′6″ 3′3″ 3′0″ 2′10″
1 – 2×10 5′10″ 5′1″ 4′6″ 4′2″ 3′10″ 3′7″ 3′4″
1 – 2×12 6′11″ 6′0″ 5′4″ 4′11″ 4′6″ 4′3″ 4′0″
2 – 2×6 5′9″ 5′0″ 4′6″ 4′1″ 3′9″ 3′6″ 3′4″
2 – 2×8 7′4″ 6′4″ 5′8″ 5′2″ 4′10″ 4′6″ 4′3″
2 – 2×10 8′9″ 7′7″ 6′9″ 6′2″ 5′8″ 5′4″ 5′0″
2 – 2×12 10′3″ 8′11″ 8′0″ 7′3″ 6′9″ 6′3″ 5′11″
3 – 2×6 7′0″ 6′3″ 5′7″ 5′1″ 4′9″ 4′5″ 4′2″
3 – 2×8 9′3″ 8′0″ 7′2″ 6′6″ 6′0″ 5′8″ 5′4″
3 – 2×10 10′11″ 9′6″ 8′6″ 7′9″ 7′2″ 6′8″ 6′4″
3 – 2×12 12′11″ 11′2″ 10′0″ 9′1″ 8′5″ 7′11″ 7′5″
Douglas fir-larch g

Western cedars h

Ponderosa pine h

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.

  1. Interpolation allowed. Extrapolation is not allowed.
  2. Beams supporting a single span of joists with or without cantilever.
  3. Dead load = 10 psf, L/Δ = 360 at main span, L/Δ = 180 at cantilever. Snow load not assumed to be concurrent with live load.
  4. No. 2 grade, wet service factor included.
  5. Beam depth shall be equal to or greater than the depth of intersecting joist for a flush beam connection.
  6. Beam cantilevers are limited to the adjacent beam’s span divided by 4.
  7. Includes incising factor.
  8. Incising factor not included.
  9. Deck joist span as shown in Figure R507.5.
  10. For calculation of effective deck joist span, the actual joist span length shall be multiplied by the joist span factor in accordance with Table R507.5(5).

JOIST SPAN FACTORS FOR CALCULATING EFFECTIVE DECK JOIST SPAN [for use with Note j in Tables R507.5(1), R507.5(2), R507.5(3) and R507.5(4)]

C/J a JOIST SPAN FACTOR
0 (no cantilever) 0.66
1/12 (0.87) 0.72
1/10 (0.10) 0.80
1/8 (0.125) 0.84
1/6 (0.167) 0.90
1/4 (0.250) 1.00

For SI: 1 foot = 304.8 mm.

  1. C = actual joist cantilever length (feet); J = actual joist span length (feet).

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