Attic weight


Hello everyone,
I just moved into a relatively new (4 years old) townhome. The attic has a small area (about 15 sq ft) that has been decked over the joists with 3/4" particle board for extra storage.
I have several questions:
1. If I want to deck the rest of the attic for storage, is 3/4" particle board the way to go? 2. How can I know the attic will support the extra weight of the decking plus the boxes/etc. to be stored on top of it?
Thanks
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Razor wrote:

The size of the joists is more relevant
--
Bill
in Hamptonburgh, NY
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Razor wrote:

This is just my opinion, and is worth exactly what you paid for it, but I would not nail down any additional decking for ease of maintenance of wiring in the ceiling below...
nate
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N8N wrote:

attics used to be built wit 25 lb per sq ft loading, so boxes of clothes ok, your entire national geographic collection, mmm, mebee mebee not, used engine blocks, no way
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My brother had an entire Model A Ford stored in his attic, engine included. Of course, it was only a small one.
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Edwin Pawlowski wrote:

You don't need a large attic for a Model T. Especially if it was disassembled.
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Regular joists or trusses? Size? Regular joists can take more weight than a truss that is designed to take the roof weight, but not floor weight.
If joists, then particle board, plywood, other cheap material is OK. Just a couple of nails to keep it from moving is OK.
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What is the difference in a regular joist and a truss?
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Older houses used joist for both the floors and the attic. Floor joists are usually 2 x 8, 2 x 10, etc, that run across the room to support the floor.
A truss is usually made from 2 x 4s, in a triangular unit of both the roof support and ceiling support for the room below it. . It will have cross bracing and a sort of web design. Very strong, they can support a lot of weight from a roof, but are not designed to be used as a floor. Couple of boxes of curtains, OK, but not for real hefty storage, like you gold bar collection. See a truss here http://www.cwc.ca/products/trusses/gable_system.php
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No, it isn't for storage- it is to give a place to get in and out of the access hole without stepping through the ceiling. 15 Sq. Feet is 3x5, not counting the access hole. 3/4 particle board is lousy decking material. Heavy, fractures with no warning, soaks up water like a sponge, etc. Builder used that because they had scraps laying around. Use 1x pine or 1/2" plywood- the cheap stuff is often on sale. You'll probably need to rip into 18" or 24" strips to get it up the access hole. Don't nail it down hard- 4 or 6 roofing nails per board is plenty, and makes it easier to pull up when, not if, you need to get to wiring underneath. <Always> put the decking joints over a joist. Forget about decking if you have insulation higher than the joists- it'll cost you big time on your heat bill, from compressed insulation. Forget about decking if the joists are smaller than 2x8- you will get nail pops and cracks on the ceiling below, from flexing. If you have trusses (attic looks like a forest, with lots of vertical members in a row), forget about more than a stripe down the middle to store empty boxes and Christmas decorations, and similar basically weightless stuff. Truss attics are not rated for heavy storage. They might hold, they might not, and no way to tell without an engineering survey.
aem sends....
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Although wouldn't the flexing be even more if one goes around the attic just stepping on the joists. A piece of floor spreads his weight ovef more than one joist. I had a lot to do up there when I first got the house. Running electrical, phone, burglar alarm wires, tv cable. Even putting in insulation requires one to move around. I put some pieces in the middle and used 2 or 3 other 16"x8' pieces, which I moved around, to reach outlying areas of my attic, sometimes lying on my belly. I couldn't lie on my belly on tthe joists alone.
And yes, one phone wire failed, so I have to move the plywood.
I agree that particle board will just break some day. Even 3/8" plywood, which is not enough for my weight so I have to put my feet above a jooist, one piece cracked once, but only one layer, and it still held. Later when I got more plywood, or T-111, I put a second layer, so in that area I can stand anywhere.

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Trusses are really designed to hold nothing more than the ceiling on the bottom chords, Something like 2 PSF. They will perform better than that because of walls that are not load bearing on the plan but still will transfer load. Try to do your "storing" on decking that is over the walls below. DO NOT nail the decking, use deck or drywall screws. You can get them back out if you have to and you have a whole lot less chance of cracking the drywall on the ceiling below.
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That's an excessively general observation. the type of truss that you generally find in a ranch-style house with a low-slope roof, is as described. But trusses are also designed with "bonus space" in the attic planned for, and those would be designed for a minimum of 30 PSF live load.
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Many thanks for all the input from everyone. BIG help.
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