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Building Development Division
Joists

MAXIMUM CLEAR JOIST SPANS

 

Pressure Treated Wood Joist Spans

 Joist Size 12" O.C. 16" O.C. 24" O.C.
2X6 9' 11"    9' 0"     7' 7"
2X813' 1"11' 10"9' 8"
2X1016' 2"14' 0"11' 5"
2X1218' 0"16' 6"13' 6"

 These are Clear Spans for Outdoor Projects.

 

Untreated/Standard Joist Spans 

 Joist Size 12" O.C. 16" O.C. 24" O.C.
2X6 40 PSF 11' 3" 10' 3"​8' 11"
2X6 50 PSF10' 3"9' 4"​8' 1"
2X8 40 PSF14' 11" 13' 6"​11' 6"
2X8 50 PSF13' 6"12' 3"​10' 3"
2X10 40 PSF19' 0"17' 2"​14' 1"
2X10 50 PSF17' 3"15' 5"12' 7"​
2X12 40 PSF23' 0"19' 11"​16' 3"
2X12 50 PSF20' 7"17' 10"​14' 7"

40 PSF is for Residential Sleeping Areas.
50 PSF is for Residential Living Areas.

 

For more information and specifications see the International Residential Code (IRC), Floor Joist Spans for Common Lumber Species.

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