Fire Treated Plywood - how to document PS 1 or PS 2 standard?

You won't win, been down that road with the same product. Plywood is no longer plywood once treated with the fire chemicals. Therefor the PS-2 or the APA stuff no longer applies.  You need to have Hoover do TVOC tests and pass to have any chance of getting credit for the product.  I ended up classifying hoover ply as part of the wall assembly (backer panels for IT rooms) and gave up on trying to seek credit for the wall category since I had other products that were wall products that also were giving me a hard time.     Also note mill work is also hard to get past IEQc2 because each built piece would need TVOC test, you can't list all the parts and pieces used for mill, work show they pass TVOC therefore the mill work passes.   My suggestion is to pay close attention to how you classify items and see if the tricky items fit into a category that you have written off, and post them in that category, to not drag down a category you have worked at building up.  In my case fire ply is no longer a wood product because the treatment voids the APA P-2 standard and is now part of the wall category because it's a backer panel component of the wall (written off category). I then used an approved softwood ps1 product in the composite wood category because that was a standalone component used as a shelf and achieved 5 categories.    I hate playing the technical games but they wrote the rules  

If I understand your question correcly, you are following v4.1 and are aware that it specifically addresses structural plywood, and that composite wood products must meet the composite wood evaluation (which does not require TVOC testing). Your reviewer is questioning exactly how you know that your Exposure 1 or better plywood (the only plywood types Hoover uses for Pyro-Guard application) is indeed manufactured "according to PS 1-09 or PS 2-10 (or one of the standards considered by CARB to be equivalent to PS 1 or PS 2)". Assuming that the PS X-XX stamp is no longer legible on the product or that you no longer have visual access to it for a photo, I would recommend looking in to the possibility of making the argument that in order to be APA rated sheathing, the product must be manufactured to these standards. (Note that I have never run the requirements of APA sheathing classifications to ground and it may be wishful thinking on my part that this is a strict requirement to obtain the APA label, but maybe there is something there.) As you are undoubtedly aware, Hoover has a public statement that the pyro-guard treatment does not contain formaldehyde - be sure to include that too if you have not already. This product is widely used in construction and needs to be recognized by the GBCI.  I see it on every project that we do firmwide. After you develop your argument and receive your final ruling, it would be beneficial to many project teams if you cirle back and let us all know how it turned out! Good luck!

I have spoke to APA engineers about this very issue, in summary Hoover ply is no longer a APA rated good because it has undergone a secondary manufacturing process after the APA manufacturing process, outside the perview of APA certified mills. APA now has no means to verify this modified product still meets APA standards.    It's like buying a new car, supping up the engine and expecting the car manufacture to honor the motor warrenty when it breaks.  It's the whole you touched it last you own it now philosophy.     It doesn't matter if Hoover says no  formaldehyde, that is only 1 ingrediant. Hoover uses a mix of stuff they will not make public, (seven secret spices) without making the chemicals public they can't pass IEQc2, and would need a TVOC test to prove the seven secret spices arent' bad for you.    

Has anyone had experience submitting fire treated plywood that is GreenGuard Gold certified in the walls category, rather than composite wood?  Looking forward to any feedback!

Does Hoover as a corporation not have a plywood sample that's been fire treated tested (one sample for each of common various fire treatments) for VOC and for formaldehyde etc. ? Why can't they do this and eliminate everyone's frustration?

Because Hoover buys plywood from differant mills depending on pricing. They would then be forced to do TVOC/VOC tests for every brand of plywood they treat and manage those records, which I assume is cost prohibitive and could vary batch by batch. Plus they don't want to test their product for fear of giving away the 7 seceret herbs and spices to competition.   Hoove doesn't mill ply they just chemically treat it.