Single Family Residential Construction Guide -

SPANS FOR CEILING JOISTS

Design Specifications:
Dead Load = 6 psf, Live Load = 10 psf (Residential)
Douglas Fir - Larch Framing
Deflection of L/360 maximum.

Allowable Spans for Douglas Fir Ceiling Joists - Residential Const.
Size of
Ceiling Joists
(inches) Spacing of
Ceiling Joists
(inches) Construction Grade
Douglas Fir No.2
Douglas Fir No.1
Douglas Fir

2 x 4 12 8'-10"
16 8'-0"
24 7'-0"

2 x 6 12 14'-6" 14'-10"
16 13'-2" 13'-5"
24 11'-6" 11'-9"

2 x 8 12 19'-2" 19'-6"
16 17'-5" 17'-9"
24 15'-2" 15'-6"

2 x 10 12 24'-5" 24'-11"
16 22'-2" 22'-8"
24 19'-5" 19'-9"

**Allowable Spans for Douglas Fir Ceiling Joists - Residential Const.**
Size of Ceiling Joists (inches)	Spacing of Ceiling Joists (inches)	Construction Grade Douglas Fir	No.2 Douglas Fir	No.1 Douglas Fir

2 x 4	12	8'-10"
16	8'-0"
24	7'-0"

2 x 6	12		14'-6"	14'-10"
16		13'-2"	13'-5"
24		11'-6"	11'-9"

2 x 8	12		19'-2"	19'-6"
16		17'-5"	17'-9"
24		15'-2"	15'-6"

2 x 10	12		24'-5"	24'-11"
16		22'-2"	22'-8"
24		19'-5"	19'-9"

Note: No credit is given for strongbacks.