CDX Plywood verses PS1 or PS2 1

[DHKpeWI]

Chapter 23 of the IBC provides diaphragm values for sheathing for Structural I grade and DOC PS1 and PS2 grades. Does CDX plywood meet the requirements of PS1 or PS2 .

 

[Lutfi]

CDX plywood is poor term to use. The CD is term to describe the finish grade of the outer plies of the sheathing. The proper term is rated sheathing. Go to APA web site and they have multitudes of data and span tables for plywood/sheathing.

Her is the link to theri web site (they also have I phone Application as well):

http://www.apawood.org/

Regards,
Lutfi

 

[Ron]

As Lutfi notes, "CDX" is somewhat of a colloquialism; however, it is generally accepted that when you use the term "CDX" you are not referring to rated sheathing. The "CDX" that you buy in a lumber yard or Home Depot is not rated sheathing and it's properties might or might not meet PS1 requirements (most likely not).

In order to use sheathing in a structural capacity it must be rated and grade stamped.

 

[woodman88]

Per the AF&PA SDPWS-08 (as referenced in the 2009 IBC) the sheathing (wood structural panels) must meet the requirements of the DOC PS1 or PS2. You should always specify the span rating and thickness for your sheathing. Plus any other requirements you need. Take a look at the AF&PA SDPWS-08 for the information you should be specifying.

Garth Dreger PE - AZ Phoenix area
As EOR's we should take the responsibility to design our structures to support the components we allow in our design per that industry standards.

 

[DHKpeWI]

The CD plywood is on an existing roof. Florida buidling Code requires the diaphragm to be evalueted when changes are made.

 

[msquared48]

Don't know how old your building is, or what code it fell under at the time of design and construction, but the UBC's of old do list diaphragm values for C-D and C-C rated ply falling under the auspices of UBC standards 23-2 or 23-3.

The "X" just meant for exterior use (since it was made with water resistant glue), such as the roof you are investigating. That's why we have the colloqualism "CDX".

Mike McCann
MMC Engineering

http://mmcengineering.tripod.com

 

[Splitrings]

Go to the APA Website and download the Plywood Design Specification. It explains the stress levels PS-1, PS-2 and PS-3.

 

[DHKpeWI]

Thanks everyone for your help!

 

[JennyNakamura]

CDX is available in Structural 1 - it will be stamped on the panel. Also, if my memory serves me correctly I believe the "X" stands for Exposure 1 not Exterior, and CDX is not recommended for long-term exterior exposure. I think they talk about this stuff in the APA Plywood Design Spec referenced by Splitrings above. I think they also show pictures and descriptions of what the manufacturer's stamps should look like so you know what you're looking at during construction observation/inspections.

 

[Splitrings]

The "X" stands for exterior glue, I believe. CDX panels are not rated for exterior use. The APA specification does not allow below C veneer grade for exterior rated panels. Structural I panels should always have an X as they are only available with exterior glue. JennyNakamura is correct, the specification shows grade stamps with descriptions.

 

[MiketheEngineer]

CDX is meant for "some" minor wetting during construction (try that with OSB - NOT) or high humidity areas.

Like suggested - go to APAWOOD and find the REAL answer!!