Plywood thickness for shop floor?

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Forum topic by Artfuldodger posted 05-19-2011 05:13 AM 3821 views 0 times favorited 6 replies Add to Favorites Watch
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4 posts in 2527 days

05-19-2011 05:13 AM

Hello, I’ve read a few post where members put 2×4’s on concrete or dirt(like Bernie). Placing the joist on 16” centers, what thickness plywood should I use? If I don’t use tongue & groove should i put cross pieces between the joist where the edge of the plywood will be. That way every edge of the plywood will be supported.

6 replies so far

View alan coon's profile

alan coon

115 posts in 3675 days

#1 posted 05-19-2011 05:33 AM

3/4 T&G would work quite well even extra shoring would help with sag. Over kill works,think what you will be puting on the floor,pounds per sq. ft.

-- Al, South E. Az., But it's a dry heat.

View Gregn's profile


1642 posts in 2946 days

#2 posted 05-19-2011 05:38 AM

I would use 3/4” plywood. If you use 16” centers your seams should fall on the centers the same for your cross supports. You could even use 12” centers if you wanted. Just be sure to use a grid work lay out to accommodate moving heavy machines around so it bears the weight equally no matter where you place heavy equipment.

-- I don't make mistakes, I have great learning lessons, Greg

View Bernie's profile


422 posts in 2799 days

#3 posted 05-19-2011 08:04 PM

Yes – 3/4” works well in my shop. And like Alan says, over kill on cross members works better then not enough. Greg is on the money 12”. Sounds like these boys were in my shop. I do have lots of cross members and as your laying down the floor, wlak on the ends and notice the saging. prop up your ply as you go along. Be flexible in your work to avoid to much flex in your floor. Good luck

-- Bernie: It never gets hot or cold in New Hampshire, just seasonal!

View Jim Finn's profile

Jim Finn

2647 posts in 2884 days

#4 posted 05-20-2011 01:00 AM

I used 3/4” T & G plywood on 16”, on center, 2×4’s layed on concrete and it works well. I put extra 2/4’s where I knew the heavy equipment would be. ( Like my table saw).

-- Website is

View Artfuldodger's profile


4 posts in 2527 days

#5 posted 05-20-2011 01:28 AM

Thanks for the advice. I’ll check it with a level and shim as necessary. It might be awhile before I do it but I’m trying to get as much info. as possible. I just registered on this sight and really like it.

View Craftsman on the lake's profile

Craftsman on the lake

2781 posts in 3400 days

#6 posted 05-20-2011 01:40 AM

ditto what many above have said. Be sure to use tongue and groove flooring or you will have seams that are not supported where they cross over to the joints. If you use regular plywood you’d have to put a second floor over the subfloor.

-- The smell of wood, coffee in the cup, the wife let's me do my thing, the lake is peaceful.

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