7/16" OSB 1

[CJJS]

Does anyone know if 7/16" OSB meets the the APA requirements for Structural 1 grade? Also, the NDS is fairly vague as to what the requirements are to meet the Structural 1 standard. Does anyone know what those requirements are?

 

[ctcray]

According to the 2003 Panel Design Spec by APA (2007 version is a free download after registering on their website), the panel would have to be graded "APA Structural I Rated Sheathing", whereas most 7/16 OSB would be graded "APA Rated Sheathing".

Also, the thinnest panel that would be Structural I rated would be 19/32".

Our lumberyard doesn't stock Structural I. We have ordered it on occasion when a contractor required it. We're in Maryland where shearwalls aren't typically utilized.

 

[RARWOOD]

As ctcray stated above unless the OSB is grade stamped Structural 1, then it is not Structural 1.

Structural 1 OSB although not common, is ussually available in the Mid West.

Unless you are on the West Coast Structural 1 Plywood is next to impossible if not impossible to get. The firm I work for is in Minnesota. The last time we inquired about obtaining Structural 1 Plywood no one would even quote us a price.

Based on past and present experience, I would never specifiy Structural 1 Plywood or OSB unless I was assured by a supplier in the project area that it was available.

 

[CJJS]

OK. Thanks. I understand that if it is not stamped with that grade, then it is not that grade. But, can you request that it be used for that grade and they test it/stamp it that way? I guess what would be nice is a reference guide that breaks down all the different types of panels based upon what grades they do meet. I have seen these for span ratings but not for grades such as Structural I. Occassionally, we see a specification for Structural I sheathing in the General Notes, but then the plans elevations/section show 1/2" Plywood or 7/16" OSB. There is obviously an inconsistency in the plans.

 

[ctcray]

Hmmm... Try mailing help@apawood.org. With plywood, i could see how they could improve the veneers of inner layers to make it stronger, but with OSB, i'm not sure how they'd do it.

i'm interested to hear what they say.

 

[RARWOOD]

The problem with catalogs from APA, WWPW ect, is that list every posssible product that could be made. As a result their catalogs often show many products that no one produces. For example if you specified Dense Select Structural Doug-Fir 2x12s, you probably could not find them any where. There in the grade rule book but probably no one produces them.

If the standard in the market is 19/32" then you aren't going to find any one who will make a small quanity of 7/16. With most mills they are running such a large quanity of material each day that it just is not ecconomic for them to turn out a small amount of custom material.

 

[NCCaryME]

With plywood, i could see how they could improve the veneers of inner layers to make it stronger, but with OSB, i'm not sure how they'd do it.

Theoretically, couldn't this be done with a variation on the recipe of resin used in the board?

The thinnest Struct I that I'm aware of is 15/32" sheathing.

 

[RARWOOD]

In glued wood products such as plywood, osb & glulam the glue is stronger than the wood.

If you can get 15/32" Struc I, use it. 1/32 of an inch will not make any difference.

 

[allisch]

well it actually will be 1/16" difference since nominal 7/16 OSB is really 13/32"
But the suggestion to use the thicker Struc I panel should be safe