Maximum Floor Joists Span

Douglas Fir and maximum span

Douglas fir maximum floor joist span for Lumber Grade Selected Structural and No. 1 and No. 2, are indicated below. Max. dead load (weight of structure and fixed loads) 10 lbs/ft2Live load is weight of furniture, wind, snow ..

  • 1 psf (lbf/ft2) = 47.88 N/m2

floor joists

Max. Live Load 30 lbs/ft2

Maximum Span (ft - in)
Nominal Size
(inches)
Joist Spacing Center to Center
(inches)
Lumber Grade
Selected Structural No. 1 No. 2
2 x 6 12 12' - 6'' 12' 11' - 10''
16 11' - 4'' 10' - 11'' 10' - 9''
24 9' - 11'' 9' - 7'' 9' - 1''
2 x 8 12 16' - 6'' 15' - 10'' 15' - 7''
16 15' 14' - 5'' 14' - 1''
24 13' - 1'' 12' - 4'' 11' - 6''
2 x 10 12 21' 20' - 3'' 19' - 10''
16 19' - 1'' 18' - 5'' 17' - 2''
24 16' - 8'' 15' 14' - 1''
2 x 12 12 25' - 7'' 24' - 8'' 23'
16 23' - 3'' 21' - 4'' 19' - 11''
24 20' - 3'' 17' - 5'' 16' - 3''

Max. Live Load 60 lbs/ft2

Maximum Span (ft - in)
Nominal Size
(inches)
Joist Spacing Center to Center
(inches)
Lumber Grade
Selected Structural No. 1 No. 2
2 x 8 12 13' - 1'' 12' - 7'' 12' - 4''
16 11' - 11'' 11' - 5'' 10' - 8''
24 10' - 5'' 9' - 4'' 8' - 8''
2 x 10 12 16' - 8'' 16' - 1'' 15'
16 15' - 2'' 13' - 11'' 13'
24 13' - 3'' 11' - 4'' 10' - 7''
2 x 12 12 20' - 3'' 18' - 7'' 17' - 5''
16 18' - 5'' 16' - 1'' 15' - 1''
24 15' - 10'' 13' - 2'' 12' - 4''
2 x 14 12 23' - 11'' 20' - 10'' 19' - 5''
16 21' - 8'' 18' 16' - 10''
24 17' - 9'' 14' - 8'' 13' - 9''

Related Topics

  • Beams and Columns - Deflection and stress, moment of inertia, section modulus and technical information of beams and columns

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