Help! Type of screw for subfloor?

[PowerDaniels]

So I was doing some reading and found that people were talking about using deck screws for their framing, but here's where I'm at.

I did my floating floor similar to that of Jake C's "Project Brutus" Bus, and I have 2" of styrofoam insulation with 2" cubes as studs down the middle of the bus to attach each 1/2" plywood panel of subfloor on top of.

Here's a picture of Jake C's bus for an example.



What I'm wondering is what type of screw I should use and length to attach into the studs. Obviously between the 2" wood stud and the 1/2" plywood, I'm looking at 2.5" of depth maximum before the steel flooring, so I was thinking I need 2" screws, but I want to make sure I use the right type since I'm out of my element.

Thanks in advance

[PowerDaniels]

Also curious about something else, I noticed there were green ones or brown ones, the green specified they're for Pressure Treated wood, so I'm wondering if there would be any issues using that type for untreated wood?

[Tango]

You can use virtually any type of screw with untreated wood, but the "new" treated stuff all require a special coating or they will disintegrate rapidly. The correct screws for the treated woods are clearly labeled as such these days.

That said, either stainless or galvanized would be my top picks for conventional wood.

[marctheprop]

Stainless is a little overkill but you're not talking that many screws so the $ difference isn't significant. General rule of thumb is embed twice the depth of the material you're affixing so 1 1/2" - 2" screws will work fine. The colored screws @ big box are for pressure treated decks-green for plain and brown if you're going to stain the deck. Either will work fine if you already own them. If you're planning a "deck/back porch" or a permanent fixture on the outside that will be exposed to the elements then stainless is the way to go-so you might buy a bigger box of stainless and be done.

[PowerDaniels]

Thanks Tango and mactheprop, I will eventually be doing a roof deck, but this was for interior right now!