attic decking/flooring recommendation?

[Vintage Veloce]

I am putting in attic trusses and was thinking about what to use for the attic floor. The contractor has recommended 3/4" OSB.

I was thinking maybe I should change that to plywood, or perhaps even actual boards. I do want to be able to put "heavier" stuff up there. Maybe not an engine, but certainly boxes of books and boxes of engine parts.

Most of the trusses are 24" apart, but there is one gap of 32" (for a future lift that I may never install so I will be flooring over that for now).

Recommendations?
C

 

[kwb]

OSB is stronger than most plywoods used in construction in most regards.

Its weak point is water, an attic floor should be a dry place.

 

[KANSASBOY]

I have attic trusses in my garage there on 24" centers with 3/4" osb . If I did it again I would you plywood because wear better because

 

[Vintage Veloce]

What/How is it wearing?

I have attic trusses in my garage there on 24" centers with 3/4" osb . If I did it again I would you plywood because wear better because

 

[KANSASBOY]

I didn't cover the osb so just walking and moving stuff has started to make it flake

 

[matt_i]

3/4 tongue and groove plywood in my attic.

Specifically, Georgia Pacific Sturd-I-Floor. I had a convenient dimension of 12' between the vertical chords, so there was no cutting of the plywood except for 3 sheets at either end of the building.

In my other shop, it was originally done not by me with 1/2" ply on 24" centers, spongy as hell. I had two options, tear out and go back with 3/4", or bought 1/2" AC (sanded and filled 1 side) and a box of big-tube (28oz) construction adhesive. Now it is very rigid.

 

[Jon_E]

I used Advantech 3/4" T&G subfloor. Screwed and glued to floor joists. It should work OK with 24" o.c. attic trusses. Paint or seal it when you are done and it won't flake off.

 

[lakeroadster]

OP: What is the live and dead load rating for the attic trusses?



http://publicecodes.cyberregs.com/icod/irc/2012/icod_irc_2012_5_sec003.htm

 

[Vintage Veloce]

I don't have the data in front of me, but I did have the attic trusses designed to accommodate LOTS of extra weight. The load won't be a problem, unless the flooring material is lead metal sheet. ;-)

OP: What is the live and dead load rating for the attic trusses? http://publicecodes.cyberregs.com/icod/irc/2012/icod_irc_2012_5_sec003.htm

 

[Justanoldguy]

OSB is stronger than most plywoods used in construction in most regards.

I would sure like to see some proof of that statement.

 

[Chris705]

See if your lumber yard has access to 1 1/8" sturdie floor. It's a osb product that will work nicely for your attic truss situation.

 

[lakeroadster]

OSB is stronger than most plywoods used in construction in most regards.

Its weak point is water, an attic floor should be a dry place.

I would sure like to see some proof of that statement.

http://bct.eco.umass.edu/publications/by-title/choosing-between-oriented-strandboard-and-plywood/

Osb and plywood share the same exposure durability classifications: Interior, Exposure 1 (95% of all structural panels), Exposure 2 and Exterior. They share the same set of performance standards and span ratings

Irreversible edge swelling has been the biggest knock on osb. Manufacturers have done a good job of addressing this issue at the manufacturing facility and during transportation by coating panel edges. But the reality is that builders don’t limit osb use to full-sized sheets. The edges of cut sheets are seldom if ever treated in the field. Houses under construction get rained on. And if you use osb in an area of very high humidity, like over an improperly vented attic or over a poorly constructed crawlspace, you are asking for trouble.

 

[strutaeng]

Plywood vs. OSB is a never-ending war. Technically, they have very similar engineering properties, so one can say they are "equal". I don't know much about the swell characteristics, so I can't comment on that.

OP: if this is for garage storage, 3/4" is probably okay. If you are concerned about flaking of the chips of OSB, lay down some 3/16 masonite on top of the OSB. It is cheap, durable, and very smooth.

For a very robust floor such as one to receive tile, 1 1/8 Sturd-i-floor is the norm, as has been recommended. You'll probably have to go to a real lumberyard to get it.

Good Luck

 

[Falcon67]

My joists are 24" OC. I used 7/16" OSB, several pieces up there were used during the build and exposed to rain, etc. There's a lot of **** up there, nothing like cylinder heads and stuff (not dragging a 55 lb cast iron head up a ladder) but seats, bumpers, left over shingle bundles, nails, scrap iron, iron pipe, transmission parts, headers, etc, etc. No problems. If you use 3/4 it should be plenty, run them long ways for best support. For the best support on the ends, you can double that joist/truss with a 2x4 so you get a full 1 1/2" to anchor the end. Not necessary but will pretty much take any flex out of the ends. I used all kinds of cuts, leftovers and such to floor parts of the attic. Some of the shorter 2' ish pieces are a bit flexy in the middle but not enough for me to punch through at a full 220 lbs sitting in the middle between joists.

>I would sure like to see some proof of that statement.
My experience is that OSB in 7/16" thickness is more stable, does not warp and is stiffer than comparable ply in a similar thickness. Ply will flex more where OSB will break but that's a product of the stiffness and how it's constructed.

As for water - I need to post a pic of the "shed" that is in the yard behind us. Build from 7/16" OSB (like you get at HD or Lowes) in 2011, no paint, no finish, exposed to whatever since then. It is still solid, it did not - has not - dissolved like you'd think from listening to the "ply people"

 

[rburke65]

I also used Advantech 3/4" T&G subfloor as recommended by my supplier on my 32' X 56' with an 8/12 attic truss, 24" OC. This stuff is not your typical OSB sheeting. Very smooth.

 

[Justanoldguy]

http://bct.eco.umass.edu/publications/by-title/choosing-between-oriented-strandboard-and-plywood/

Osb and plywood share the same exposure durability classifications: Interior, Exposure 1 (95% of all structural panels), Exposure 2 and Exterior. They share the same set of performance standards and span ratings

Irreversible edge swelling has been the biggest knock on osb. Manufacturers have done a good job of addressing this issue at the manufacturing facility and during transportation by coating panel edges. But the reality is that builders don’t limit osb use to full-sized sheets. The edges of cut sheets are seldom if ever treated in the field. Houses under construction get rained on. And if you use osb in an area of very high humidity, like over an improperly vented attic or over a poorly constructed crawlspace, you are asking for trouble.

SB is stronger than most plywoods used in construction in most regards.
???????

I'm not yet convinced one little bit.

 

[lakeroadster]

SB is stronger than most plywoods used in construction in most regards.
???????

I'm not yet convinced one little bit.

I'm not an OSB fan either. Perhaps it's an "Old dogs and new tricks" thing?

I'm qualified to make that comment, on both accounts.

 

[Falcon67]

I'm not an OSB fan either. Perhaps it's an "Old dogs and new tricks" thing?

I'm qualified to make that comment, on both accounts.

I'm a fan of covering 32 sq/ft with usable surface for $8, which was the cost of OSB when I built. 3/4 ply was over $30.

 

[R. Deschain]

Another vote for 3/4 T&G plywood. Apply construction adhesive to the joists and panel joints and screw it down with deck screws.

 

[Slednut]

Like said above, this stuff.

http://www.menards.com/main/osb/1-1...38203317-c-13333.htm?tid=-7877893040983515695

 

[brianw74]

I would think 3/4 would be quite a bit less expensive than the thicker product and easier to work with up in the attic it is plenty strong enough. Put a coat of primer on it and you will be set.