attic flooring

[Bruce A. King]

Many new homes around here have trusses 24 on center, most of the attic floors are double thickness OSB (7/16) when furnaces and water heaters are present.

Some have single 7/16 OSB spanning 24" where the attic is only for storage.

The access on all examples is folding stairs or ceiling scuttles.

The single layer 7/16 has a span limit of 16 inches.

Any difference in IRC code because this area is only for storage?

In other words, is 7/16 OSB ever allowed to span 24 inches when used in storage areas without regular access?

[Richard A. Hetzel]

Sometimes "Storage" in the code requires much greater design live loads than normal usage, but I'm not sure if that's true of the Residential code. Attic live loads are usually 20 PSF.

[Bruce A. King]

Seems dangerous when a 240 lb person can put 240lbs on one footprint.

Since the material is rated for 16 on center when used for flooring, it's just improper but not enforced around here much.