Floor an Attic for Storage

MrBill_DIY · 05-07-2008, 07:15 PM

I have a large (400 square foot), 13-foot-high attic that I am turning into a big storage room and occasional workshop (but not a finished living space). About 70% of the attic is already covered with 1/2" plywood, with 2x6 joists, but the floor feels spongy and I'd like to stiffen it up some because I want to use the attic for light storage. I have a neighbor with exactly the same attic, and he used 5/8" particleboard from Lowes to floor his attic, and his floor is very stiff, just like I'd like mine to be. However, I have read a lot of posts that say to stay away from particleboard because it swells up if it gets wet, so I'm wondering what I should use instead. Is there anything as stiff as particleboard, but without the problems? Obviously, I could just pull up all the 1/2" plywood and replace it with 3/4" plywood. I suppose CDX plywood would be standard?

Floorwizard · 05-10-2008, 10:47 AM

absolutely.

no problems with that...

troubleseeker · 05-12-2008, 09:55 PM

Stay away from the particle board. I have seen PB used as attic flooring, and after a few years in the heat, it became so brittle that you could step right through it. The floor most likely feels spongy because the 2 x 6 joists were intended to be ceiling joists for supporting the drywall below, not floor joists; thus they are under sized and most likey over spanned for any kind of live load like you plan.

MacRoadie · 05-13-2008, 12:56 AM

Quote:

Originally Posted by troubleseeker

The floor most likely feels spongy because the 2 x 6 joists were intended to be ceiling joists for supporting the drywall below, not floor joists; thus they are under sized and most likey over spanned for any kind of live load like you plan.

Exactly. Light storage would likely be pushing it. Using the attic as a work space with those 2x6's could be problematic.

MrBill_DIY · 05-13-2008, 07:02 PM

The joists are 2x6s, and they are undersized for a normal floor, but they are on 12-inch centers instead of 16-inch centers. I'm going to keep the heavy weight off the weakest part in the middle of the longest span. The walls are solid masonry, so the storage will go on shelves attached to the walls -- nothing heavy will be on the floor. But I would like to stiffen things up for walking on, short of actually reinforcing the floor with sister joists. It sounds like particle board deteriorates over time, even if it doesn't get wet. So maybe I should just use 3/4" plywood, and upgrade from the 1/2" plywood that's there now. I was just impressed with how stiff the 5/8" particle board is in my neighbor's attic.

bofusmosby · 05-13-2008, 07:32 PM

I put some plywood down in my attic several years ago for storage. The rafters are 2 X 6's, and I know what you are talking about having to do with the spinging-ness. Is that a word?

Well, even though I have the floor covering half the attic, I am careful to store most items over existing walls from below. This way, there is plenty of support.....I hope.