Superior Wood Structures ltd
Wood I Beam manufacturer

AMERICAN ALLOWABLE FLOOR SPANS TABLE

LIVE LOAD: 40 PSF, DEAD LOAD:10 PSF

 

Simple span
Series

Depth (inches)

On-Center Spacing
12" 16" 19.2" 24"
SIB 30 9 - 1/2 17' 3" 15' 10" 14' 11" 14' 0"
11 - 7/8 20' 6" 18' 9" 17' 9" 16' 6"
12 - 1/2 21' 3" 19' 6" 18' 5" 17' 2"
14 23' 2" 21' 2" 20' 0" 18' 8"
16 25' 7" 23' 5" 22' 1" 20' 7"
SIB 31 11 - 7/8 22' 0" 20' 1" 19' 0" 17' 8"
14 24' 11" 22' 9" 21' 6" 20' 0"
16 27' 6" 25' 1" 23' 8" 22' 1"
SIB 41 9 - 1/2 20' 6" 18' 8" 17' 7" 16' 4"
11 - 7/8 24' 4" 22' 1" 20' 10" 19' 4"
12 - 1/2 25' 3" 23' 0" 21' 8" 20' 2"
14 27' 6" 25' 0" 23' 7" 21' 11"
16 30' 4" 27' 8" 26' 0" 24' 0"

Multiple span
Series

Depth (inches)

On-Center Spacing
12" 16" 19.2" 24"
SIB 30 9 - 1/2 19' 4" 17' 8" 16' 8" 15' 0"
11 - 7/8 22' 11" 21' 0" 19' 4" 17' 4"
12 - 1/2 23' 10" 21' 9" 20' 0" 17' 11"
14 25' 11" 23' 5" 21' 5" 19' 2"
16 28' 7" 25' 4" 23' 1" 20' 8"
SIB 31 11 - 7/8 24' 8" 22' 6" 21' 3" 19' 2"
14 27' 11" 25' 5" 23' 9" 20' 8"
16 30' 10" 28' 1" 25' 9" 20' 10"
SIB 41 9 - 1/2 22' 10" 20' 10" 19' 7" 18' 3"
11 - 7/8 27' 2" 24' 9" 23' 3" 21' 2"
12 - 1/2 28' 3" 25' 9" 24' 2" 21' 9"
14 30' 9" 28' 0" 26' 4" 22' 5"
16 34' 0" 30' 11" 26' 0" 20' 10"

Notes to tables:

  1. Maximum live load deflection is limited to L/480 and maximum total load deflection is limited to L/24.
  2. Floor sheathing shall be attached as addressed in Conditions of Use.
  3. Span is distance measured between centerline of supports.
  4. Minimum end bearing shall be 1-3/4 in., minimum interior bearing shall be 3-1/2 in.
  5. Lateral bracing shall be provided at bearing locations.
  6. Bearing stiffeners shall not be required.
  7. For multiple spans, the adjacent span shall be at least 80% of the longest span.
  8. Span values to the right and below the heavy line are governed by reactions at the support.
  9. 1 in. = 25.4 mm; 1psf = 47.9 Pa; 1ft = 304.8 mm.