ALLOWABLE SPANS FOR FLOOR JOISTS


Design Specifications:
Dead Load = 12 psf, Live Load = 40 psf (Residential)
Douglas Fir - Larch Framing
Deflection of L/360 maximum but never more than 1/2 inch.

Allowable Spans for Floor Joists
Size of Floor Joist
(inches)
Spacing of Floor Joists
(inches)
No.2
Douglas Fir
No.1
Douglas Fir
2 x 6 12 9'-9" 10'-0"
16 8'-11" 9'-1"
24 7'-5" 7'-11"
2 x 8 12 12'-11" 13'-2"
16 11'-6" 12'-0"
24 9'-4" 10'-0"
2 x 10 12 16'-1" 16'-4"
16 14'-0" 15'-0"
24 11'-5" 12'-3"
2 x 12 12 18'-8" 18'-11"
16 16'-3" 17'-5"
24 13'-3" 14'-2"

Design Specifications:
Dead Load = 18 psf, Live Load = 40 psf (Residential)
Douglas Fir - Larch Framing
Deflection of L/360 maximum but never more than 1/2 inch.

Allowable Spans for Floor Joists
Size of Floor Joist
(inches)
Spacing of Floor Joists
(inches)
No.2
Douglas Fir
No.1
Douglas Fir
2 x 6 12 9'-5" 9'-8"
16 8'-7" 8'-9"
24 7'-0" 7'-6"
2 x 8 12 12'-5" 12'-8"
16 10'-10" 11'-7"
24 8'-10" 9'-6"
2 x 10 12 15'-4" 15'-11"
16 13'-2" 14'-2"
24 10'-10" 11'-7"
2 x 12 12 17'-10" 18'-5"
16 15'-5" 16'-6"
24 12'-7" 13'-5"


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