Floor Attic For Storage Question

[srv52761]

This will never be used for anything except Decorations and old photos and slides my wife wants to keep.

   

Consider adding  a dedicated outlet and some sort of drain to the plumbing or to the outside.
It appears a lot of days in the Dallas area  have relative humidity higher than the recommended for mold prevention.  
If you plan to store things there, and I assume they have value to you, you may want to invest in a dehumidifier.  Water vapor is lighter than O2 and whatever the relative humidity is outside, it will be 5-10 percent higher in an attic.  
If you provide for continuous drainage for a dehumidifier you can plug and forget.  Most have  humistats that are reliable enough for your needs.  60% is the magic number I use as our max, but we strive for 50% or lower.   In fact you should strongly consider lower.

Relative humidity is a function of water vapor and temperature.  The greater the temperature the more water vapor the air can hold at 50% rh.

Mold spores need water vapor. 

 I suspect some days in Dallas get pretty hot, and attics even hotter, say 130*-150*.  There is a lot of water vapor, even at 50% rh.

[GDay]

All that being said...

If I were going to forgo a proper support beam, I'd use a 23/32 sub-floor material called AdvanTech. It's made by Huber. Lowes (Not Home Depot) sells it in 23/32 for about $20 a sheet. It's a very high density and very flat tongue and groove OSB.  You'll see the difference between it and generic T&G OSB as soon as you look at it, feel it and lift it. Much less deflection, much more water resistant, much better shape retention (stays flat). It's very hard so you might want to use a nail gun for install. If you don't have a nail gun, consider using construction screws like these "partial thread" Spax 2-1/2" #8  Here
Make sure you use the "partial thread" with the flat head to pull the sub-floor tight to the joists. I'm guessing you could find a larger qty. box at a better price online somewhere.

Neil, do you suggest this material as a way to make the 2xi0 joist I have stronger as a support unit? I am just trying to wrap my head around this situation. This space will be used for storage with as much along the areas closet to the outside walls as possible. I am not against the floor being a little bouncy when walking around. If this material makes the floor stronger,less bouncy would be a bonus. Anyone else that wants to comment on this is invited to join in also. I also like the idea of laying down 2x4 on 16” centers does this additional weight become offset by making the garage floor system more suppottive. Adding any kind of beam below is not an option. Thanks again!
gary

[DieselDennis]

Here's betting that he can't get a 4x8 sheet of anything through his attic door.

So unless he's going to mill his own T&G into his ripped down sheets, it's a moot point.

If you care enough to seek advice on this topic, then you care enough to lay down your money on some 3/4" BC plywood and call it done.

[GDay]

Here's betting that he can't get a 4x8 sheet of anything through his attic door.  

So unless he's going to mill his own T&G into his ripped down sheets, it's a moot point.

If you care enough to seek advice on this topic, then you care enough to lay down your money on some 3/4" BC plywood and call it done.

That was very helpful! You don’t have a clue how I intend to get sheet stock up there. I am tryingto understand how thicker material which is heavier is going to make things better if the joists are considered marginal. Thanks a lot for your informative post.

[Snipe Hunter]

Not sure the AdvanTech flooring will do anything (not much anyway) about the "bounce" along the span of the joists but will reduce the sag/bounce between the 24"oc joists that would be noticeable using a non T&G 19/32 OSB with or without the H-clips. Adding the beam will get rid of the bounce. I recommended the AdvanTech floor because of it's strength, moisture resistance and durability properties which are better than the cheaper T&G OSB sub-flooring. It's cheaper than T&G Plywood. Plywood is nice but like all home improvements, budget is always a factor in materials selection. The advantage of the AdvanTech over plywood is it's moisture resistance. Generally unconditioned attic spaces have some moisture (humidity/condensation) hurdles that conditioned spaces don't have.

[tomsteve]

I made a real goof on this thread. The useable space is only 8’x25’ down the center of the garage. The tongue and groove might be worth the cost. The 2x4 blocking on 19/32 is also a good option. Thanks for all the help and waking me up.
Gary

can ya snap a few pics of what ya have to work with and post em here? it reads like your working on top of the BC of trusses.

[Snipe Hunter]

can ya snap a few pics of what ya have to work with and post em here? it reads like your working on top of the BC of trusses.

+1

[GDay]

+1

[GDay]

The openings are for attic stairs and a Versalift.

[GDay]

This is half the garage space, the vertical roof support is pretty much the center. I had to figure out how to post the pictures. I have a video also. I could not add it. The 2x6 running down both sides on top of the joists have room for a 4’ wide deck close to the walls. The storage will be mostly along the walls and the center 8’ wide are for walking about.
Gary