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Calculating load for OSB flooring Question
I have a 1/2in OSB board with "32/16" stamped on it. This means that when used as flooring, it the supporting joists must be spaced 16in or denser (32 is for roofing).
However, if I did put it on 16in spaced joists, what load would it actually be able to carry in pounds?
1 answer
The span ratings are generally deflection limited for most applications, not breaking load limited.
Includes a table (2a) for Oriented Strand Board (OSB) Sheathing, and a separate table (2b) for OSB Structual I Sheathing, and a third (2c) for OSB Sturd-I-Floor (which is not given a roof span rating.)
You have not specified the complete details of the stamp, so we don't know if you have "Sheathing" or "Structual I Sheathing" but we know it's not Sturd-I-Floor.
Correctly oriented 32/16 Sheathing at 16 inch spacing has loadings in table 2a from 188 to 376 lbs/square foot. Incorrectly oriented they range from 41-228 lb/square foot. So Very Conservatively (at L/360 deflection), a 4x8 sheet would hold 1,312 lbs (improperly oriented) or 6,016 lbs (correctly oriented.) If the loading condition did not invoke bending failure (6,688) or shear failure (7,296) the sheet could hold 12,032 lbs at L/180 deflection. These total loads are for uniformly distributed loads, not anything smaller than the full 32 square foot sheet.
Correctly oriented 32/16 Structual I Sheathing at 16 inch spacing has loadings in table 2b from 188 to 376 lbs/square foot. Incorrectly oriented they range from 65-228 lb/square foot. So Very Conservatively (at L/360 deflection), a 4x8 sheet would hold 2080 lbs (improperly oriented) or 6016 lbs (correctly oriented.) If the loading condition did not invoke bending failure (6,688) or shear failure (7,296) the sheet could hold 12,032 lbs at L/180 deflection. These total loads are for uniformly distributed loads, not anything smaller than the full 32 square foot sheet.
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