cross state bet

[pushkins]

I have a bet with a mate in Ohio on sub flooring.

He says that it is better to put down 1/2" first (over the floor joists) build your walls and roof then come back and lay 3/4" over the top of it once it is considered a "dry" space.

I have always put down the 3/4 first, usually Advantech or the like, built the walls and roof then ( if needed for any reason) added the 1/2".

The bet is he says his way is as strong as my way, I disagree because you cannot lay the two layers on the same direction (joints would line up) therefore the 3/4" down first would have a better hold on the floor joists and if needed the 1/2" could then run in the opposite direction and be screwed down to the 3/4".

I'm up on bets with him with OSU loosing two years running, love to make it three if anyone has some facts somewhere.

[Mr T]

What the heck are you doing that you need 1.25" of floor? That's alot of extra expense if you got a large floor footprint.

3/4" is usually fine for most cases. Especially if its something like tongue and groove OSB. My house from the 50's (when plywood just came around) has 1/2" on the floor. It is soft in areas but holds up. I glued/screwed another layer of 1/2" down in the laundry room when I redid it and it's a tough floor.

Putting down 3/4 after you have your walls up cuts your bottom plate drywall nailing surface in half. Not too big of a deal...

2 layers is possible you just offset the seams.

Yea OSU can loose all they want... I wonder what kind of football team they are buying this year?

[pushkins]

The bet is not "if" you can do it, of course you can , the bet is what way would be stronger 1/2 then 3/4 or visa versa.
Mr OSU lover says that laying the 1/2" down and then adding the 3/4 over the top makes the same structural strength as 3/4 first then 1/2" nailed to it.

My thought is that 1/2" nailed down to 3/4 that is nailed down to floor joists is stronger simply because of the thicker material nailed directly to the floor joists first.

[Mr T]

What are you using? plywood, OSB, styrofoam, poured chocolate, ect?????

If it's plywood, it would also depend on how many layers it has and its composition.

Strength in what form? resistnace against flexing, stress/weight failure, impacts, ect?

It would also depend on how you lay it all down, if you glue the layers together it may behave as a single piece of wood and it wont matter whats on top..

Plywood and OSB both are composed of smaller pieces of wood.. In a stress or load failure the individual pieces are failing one at a time where as a solid piece of wood failes as a whole unit (in a nutshell)

I'm not a stress engineer but I dont think 1/2 ontop of 3/4 vs 3/4 on 1/2 will be comparable to a 2x4 on a 2x8 vs a 2x8 on a 2x4.

Chances are in a 14.5" span (16 O.C.) there is gonna be minimal difference and it wouldnt fail on any household conditions. (in other words you wont be driving a cement truck onto it).

In other words, you are going to need a test lab to determine this.

Let me save you the expense....The following should answer all your questions....

Q: What are the three longest years of a Ohio State football player's life?
A: His freshman year