Availability of Structural I sheathing in the US

[JAE]

Does anyone have any experience as to availability of Structural I rated sheathing in the US?

I seem to recall that it is definitely available on the west coast and in another post in 2008 someone mentioned the "upper midwest".

Do you typically specify Structural I or simply the other rated sheathing types listed in the IBC diaphragm/shear wall tables?

Sometime way back I was told that OSB substitution for shearwalls was OK as long as the OSB was rated for Structural I. If not, you should insist on plywood. Is this true?

 

[RFreund]

1.) I'm not sure as to the availability around the entire US but in the Midwest it seems to be available but not usually a "Stocked" item.

2.) We usually do not specify structural 1 unless needed.

The odd thing about sheathing is this: The shearwall and diaphragm tables list min. thickness. However plywood and OSB are rated by the APA (Structural 1, 32/16, 40/20, etc.). We usually specify both the thickness and the APA rating so that some OSB that has no rating but satisfies the minimum thickness is not used. Plywood also has different plys (3,4 and 5 ply). We usually specify 5 ply just because if you have trusses @ 24" on center 3 ply is pretty flexible (out-of-plane). If you look at the Panel Design Specification 2008 by APA they will show you how they all relate:
Thickness Vs APA Rating - Table 5
#of Plys Vs APA Rating - Table 7

I'm not really sure if that answers your question.



EIT

http://www.HowToEngineer.com

 

[MiketheEngineer]

Generally hard to find and it may tqake a while to get it. Try something else.

 

[msquared48]

I generally never spec Structural 1. I always use CDX - do not like to use OSB, but have.

Mike McCann
MMC Engineering

http://mmcengineering.tripod.com

 

[boo1]

We specify the APA rated plywoods.

 

[efsinc]

Struct I APA rated sheathing is readily available and commonly used in California. Could be wrong, but it seems like most non residential structures, especially roofs, are using struct 1. Specifying as APA rated allows OSB or Plywood. So specify according to your belief in those products.

 

[RHTPE]

JAE - Struct I plywood is commonly used for concrete forming, usually available in 1/2", 5/8" & 3/4". It's usually a 'B' veneer both sides. Depending on how critical your application is, the cost will be a consideration since it's definitely pricier than sheathing.

Ralph
Structures Consulting
Northeast USA