I see 3/4" tongue and groove plywood called out in the diagram.  I would expect plywood,  not OSB.  But it also depends on what is in your Builder’s specs and whether they are following the architectural drawings completely. Sometimes builders will default to doing things the way they've always done them and assume no one will have an issue with it.

TT, is that something they can just change? I too see that read as plywood and not OSB. What they have in as subflooring is NOT plywood. It is OSB I believe.

Email your builder for an explanation. This creates a record.

" Horizontal CDX will delaminate when left uncovered for as long as it takes to dry in these days "

Who said and where does it say CDX? It says T&G Plywood and CDX is not available T&G as far as I am aware. Advantech is an OSB and would be fine.

What does the "FRAMING PLAN" call for?

“Who said and where does it say CDX? It says T&G Plywood and CDX is not available T&G as far as I am aware.”

Well they are not going to use A/B grade plywood for subfloor and CDX is widely available in T&G.

@mark the framing plans states t&g plywood. Then I found in the builder allowances, they state this: “All work up to and including drywall will be completed per architectural prints. No allowances are to be provided for this work. Any necessary deviations due to unforeseen variables are allowed as long as the design meets the Authority Have Jurisdictions inspection requirements and passes AHJs inspection.”

Then next to subfloor, it says: “Subflooring to be 3/4” T&G plywood, or OSB sheathing or equivalent per the builders discretion.”

I guess they found a way to get around the architectural prints on everything.

Since you are an architect, can I ask, do you approve builders to deviate or have the option to deviate from the plans wherever they see it makes sense for them structurally or financially? It just seems like they take the plans and basically modify them or find ways to be able to ultimately do whatever works for them. Is this always known and approved by the architect as well?

They’ve done this with many things, even initially included the window orders for the home in the contract. The plans called for a double window (the exact same size as the other two in the front of the home.) The specs, rendering pics, window order and the rough cutout was for this window. While on-site last week, there was only a single window installed. The rough cutout was boarded up and covered in a different wrapping so you can see where the window cutout clearly was. When I asked the builder what happened, he said what do you mean? I said, well to the window? He straight up lied. He said the rough cut out was the wrong size and didn’t line up with the specs and window ordered for this room. Both of those things are not true. The window order is a receipt and it’s broken down by room. The specs show the window on the order and rendering pictures have the double window in every single picture. If they have the approval to change or deviate from plans, why did he lie about it?

Welcome to my world.

My bad on the T&G. Usually I always see it as T&G Underlayment, not CDX or sheathing grade.

@mark can you explain your comment?

No one changes anything without my approval on my projects but the specs do rule when theres a discrepancy.

I would approve Advantech OSB

Our architect's plans clearly call for different sub-flooring depending on which page you look at.

Without careful oversight, many trades just do what they're used to doing, the heck with specs. The worst in our area are concrete formers. "We don't need no steenkin' vibrators." (No, not those!)

I have sub-floors glued, screwed and nailed. On a homeowner built 4,800 sf we watched in wonder as the "carpenters" used white glue instead of construction adhesive.

Many times builders or clients or the combination thereof will change things without notifying me, most often to their detriment. I will bring it to their attention and sometimes they will see the reasoning and change it, but often they do not want to spend the money it would take to correct their error.

Builder's notes are typical. Use of OSB is typical unless a more specific plan call out exists. Plans are not always consistent between architect's & engineers pages as well as from the bid sets to the final sets. (have 2 AIA sets like this now). Framers & lumber yards will always defer to engineering pages.

Most clients prefer a better price. Was building one in 2021 with specific plywood call outs that we used at shear (exterior wall cladding). The lumber yard delivered OSB for the roof, not the plywood I had asked for. Client had called to change to save $$. (lumber yard was his relationship & last time I used them). There was some joint transparency through the comp roofing that eventually it went away.