Flooring for 24" on center joists? Doubled up OSB?

just put crosspieces and the case is close

1

I'm not at all ignorant, but I am confused especially in answer # 1? You pretty clearly state JOISTS/RAFTERS exist? Am I wrong to assume that? Then you mention 1 x 6 ???

If you have any manner of construction according to ANY code at all; your joists should be no less than 2x8 and certainly 2x10 might be preferred. You also don't state any SPAN? OR support aiding the joists,,,if in fact they do already exist.

With no offense CHEAP/Fast are relative words; but certainly you've already been shopping, and have prices listed here...which may vary by location and availability elsewhere. Storage or living space...the subfloor doesn't strictly matter. Obviously OSB/MDF are more widely used in todays construction context. So in essence the sub floor will be fine as you suggest; providing the Joists/rafters are substantial enough to hold the weight. the 24 inch on center is pretty standard; but again I'm confused by the 1 x 6. If they happen to be 2x6, I'd probably be looking to support them somehow...even if it meant Hanging and bolting doubles to them.

Steven Wolf

Depending on the width of your garage( how wide is the span) how far apart are the upright braces? You may want to think about adding some of those depending on what you're putting up there as storage.1/2" OSB doubled or single with 2x4 underneath as centerbrace is fine. 1x6 for flooring is a little weak unless its nailed down. You don't want the ceiling joists coming down on you. You might think about 5/8" OSB T&G

A lot has to do with what your storing up there and the size of the ceiling joists we know they are 24 inches apart.This explains 5 different answers, your going to have to be more specific. Re:Addit. info.2x10 joists, 1/2 osb should do it single layer for general storage, the joists carry the load I think a double layer is over kill.

if this is just a storage area and not actual living space, I'd go with the OSB, doubled as you describe. Screw the OSB to the rafters and then glue the second layer of OSB on to the first layer with construction adhesive, overlapping the joints in the first layer. this will mean cutting for you. Screw the top layer down to the first layer.

Here's a caution- if you do it this way.. you will NEVER get it out without cutting the entire section of OSB out.. but you will have a pretty good, sturdy attic floor.

Are they rafters or trusses.

If you are "just storing 1/2" is adequate depending on the pitch of the roof. with a 2x10 bottom chord you should have more then adequate capacity for just 1/2" unless you intend to have appliances in an true attic room.

you don't need sturdy floor if your weight bearing is less then 40lbs per sf.

Check with your building dept or contact the truss department at a local building center. Engineering on trusses is done for extreme conditions. Stick built rafters change the loading a bit, you may need to build in cross members to actually support the middle span.. I had trusses engineered for a garage we built last year. We had them design a spread web. 6" bottom chord. more then adequate to meet most needs.

check your local code.

think about making the rafters 12 instead of 24, less creeking - more strength and then you can use whatever for the actual floor.

Sounds like you will need more strength if you are going to use it as storage.

ASSUMUNG YOUR JOIST ARE SPACED & SPANNED CORRECTLY..... YOU NEED 1 1/8" STRUDY FLOOR PLYWOOD - LUMBER YARD