Decking an existing attic.

[dbhost]

Not sure why, but the attic above my workshop was decked with T1-11 ply siding. I guess it was left over. I want to pull this stuff out and A. Do the decking right with (Insert an affordable suggestion here) AND extend the decking so that it goes back over the master bedroom as well... Lighting has been run to the space, I have 3 boxes, with single bulb fixtures, mounted sideways on the cross beam on the rafters. These are fitted with CFLs that are the 100W replacement variety. So there is sufficient lighting up there...

My questions are:

A.) Is OSB appropriate for this purpose? It's a LOT cheaper than ply, and MDF is out of the question.
B.) How on earth do I get the material up into the attic?
C.) What other "gotchas" do I need to consider when doing this?

If it's not obvious, yes I have storage problems, and am trying desperately to solve them. You northerners with basements wouldn't understand...

[crokett]

I am a Southerner (well transplanted ), have a basement and still have storage problems.

A. OSB works fine as attic decking. It is what is in mine now and I will put more up there this weekend
B. You need to rip it to width/length that you can get into your attic through the existing opening.
C. Is your attic framed with trusses or joist/rafter? What size (2x4 or 2x6) trusses? Joist/rafter will generally carry more weight. I have a hallway running down the middle of my truss-framed house and I only plan to add enough decking so the stored stuff is sitting over the hall walls. I won't be putting anything over the clear span in the kitchen/living room.
D. What is your existing access? Mine was a 2x2 opening in one of the closets. Unless you don't plan to be up there more than 1-2 times a year I would seriously consider a set of pull down stairs.

[dbhost]

Joist / Rafter construction. Not sure of the size of lumber under all the crud, looks like 2x6 or 2x8...

[RayintheUK]

That's excellent advice from David.

In the UK we can buy packs of suitably-sized Chipboard with T & G edges, specifically to deck attics. Is that sort of thing not available in your big DIY sheds over there? Here's a link to a relevant article, in case it's of interest.

Ray

[pelligrini]

Is existing t11 laid wrong? If the area that it is covering is ok, I would just lay down another layer of osb on top of it if deck strength is an issue. Unless you really want to remove it. To save in cost you could use a thinner osb over the existing decking.

[dbhost]

Is existing t11 laid wrong? If the area that it is covering is ok, I would just lay down another layer of osb on top of it if deck strength is an issue. Unless you really want to remove it. To save in cost you could use a thinner osb over the existing decking.

Hadna thunka that...

Some of the T1-11 has uh, foot holes in it...

There's a danged good reason I want 3/4" up there!

[pelligrini]

I would certainly think you could lay down 1/2" material over the existing t1-11 and get very close to the same as ripping it all out and using all 3/4 OSB. I haven't priced OSB in a while. There might be enough savings to warrant using a thinner material.

You didn't mention how thick your insulation was. It would be easier to make sure the spaces under your the decking were adequately insulated now...

[DustyandLefty]

don't pound

Use screws, not nails! You really do not want to be pounding on the joists as the impact will transfer straight to your ceiling drywall.
Dusty

[dbhost]

I would certainly think you could lay down 1/2" material over the existing t1-11 and get very close to the same as ripping it all out and using all 3/4 OSB. I haven't priced OSB in a while. There might be enough savings to warrant using a thinner material.

You didn't mention how thick your insulation was. It would be easier to make sure the spaces under your the decking were adequately insulated now...

Over the living space, the void is completely filled. R19 I guess it is, over the garage there is a complete absence of insulation...

The existing T1-11 can't possibly be more than 3 sheets worth... So ripping it out isn't exactly a heart breaker. I will need to go with OSB or something similar in 3/4" anyway...

Since the garage is the workshop, and it appears will stay that way, and I have already insulated the doors, I was planning on rolling in and packing the voids with R19 batts. I guess I am going to need, uh... Let's see, each roll covers something like 75 square feet, and I need to cover 400 square feet so that would be6 rolls with some leftover probably to patch areas by the A/C that got screwed up as well. Each sheet of OSB covers 32sq ft, and I should have about 800 sq ft to cover. That would mean 25 sheets. So figuring IF prices are what they were when I bought the OSB for closing off my windows for Ike...

3/4" OSB 4x8 sheet $10.95 x 25 = $273.75
Owens Corning unfaced R19 75sq foot rolls. $29.95 x 6 = $179.70
I have about 10lbs of misc nails, mostly 8d common that should be adequate for the purpose. So nails are a no cost item basically.
Subtotal for materials then would be $453.45 add to that 8.25% sales tax, or $37.41 giving me a grand total of $490.86.

Is my thought process and math right on this?

[dbhost]

Use screws, not nails! You really do not want to be pounding on the joists as the impact will transfer straight to your ceiling drywall.
Dusty

Good point! Which is why I ask...

[RayintheUK]

Have you seen this as an alternative?

Ray

[dbhost]

That is either a REALLY good idea, or a really bad idea. Not sure which...

As far as the joists are concerned, I was up there again last night, and I am not sure about the depth, it is definately 2x material, but I might have 2x10s up there! They looked freaking HUGE...

[crokett]

Ray,

That stuff is expensive - 5 bucks a square foot? I can pay 15 bucks for a 4x8 sheet of OSB and it only takes a few minutes to rip it to size.