Plywood on a concrete garage floor?

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Forum topic by Brett posted 09-27-2011 10:49 PM 20482 views 0 times favorited 18 replies Add to Favorites Watch
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684 posts in 3745 days

09-27-2011 10:49 PM

My workshop is in a garage with a concrete floor. If I want to have a wooden floor, can I just lay sheets of plywood on the concrete (as if they were stiff rugs)? Will the plywood eventually rot? Could I put a sheet of plastic under the plywood to keep moisture away? What problems are there with just laying plywood onto a concrete floor?

-- More tools, fewer machines.

18 replies so far

View MedicKen's profile


1615 posts in 4524 days

#1 posted 09-27-2011 10:59 PM

I have built a floating plywood floor over my concrete. 2×4 sleepers flat on 16” centers and 1 1/2” styrofoam insulation between them and then 1” T&G ply screwed to them. I passed on the plastic vapor barrier as I am in a very dry climate. I think it would depend on your area of the country and whether a vapor barrier is required in construction if that would be necessary. Concrete is a big sponge and if the soil underneath is wet the ply will eventually rot

-- My job is to give my kids things to discuss with their [email protected]

View dbhost's profile


5777 posts in 4294 days

#2 posted 09-27-2011 11:29 PM

I have also considered this to take a big part of the strain off my back. However… How do you compensate for the sloping floor? Around here all of the garage floors slope toward the door to insure any water that gets IN the garage goes right back out…

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View JimDaddyO's profile


666 posts in 4141 days

#3 posted 09-28-2011 01:52 PM

wood should never come in contact with concrete. Moisture wicks and it will rot. You need a barrier. Why not just put an epoxy garage floor coating down?

-- my blog: my You Tube channel:

View Deaner's profile


45 posts in 3148 days

#4 posted 10-24-2012 04:37 PM

Well, here I go. I’m gonna put a 3/4” floating plywood floor down on my concrete flloor. Not gonna use any sleepers, and not gonna use tongue and groove either…just good ol’ 3/4” AC grade plywood.

I did a vapor test in my shop by duct taping a 14” x 14” square of heavy mil visqueen and observed for the last 10-12 months that no moisture or condensation formed under the visqueen.

Alas- no moisture or condensation formed. Far out!!!

So now I am gonna lay down a nice heavy felt paper over my 30’x40’ concrete shop floor to float my plywood on. The slope inherent to most shop floors is negligable…so I won’t sweat that part.

I am gonna use unglued biscuits and with good clean square panel cuts to keep my floor flat and fit- and to allow moving and shrinkage.

Now then, could a fellow jock tell me what I’m over looking? Please talk me out of anything that seems stupid with my floor project!
Thanks for any interest:)


-- Once harm is done, even a fool understands it.

View comboprof's profile


277 posts in 2796 days

#5 posted 01-06-2014 09:19 PM

I know its been over a year now since you did your renovation, but I am curious how it all worked out.

It is -6 today and although my garage shop is heated. The floor is so cold I can only stand on it for an hour. Hence This summer I may do something to the floor.

BTW I have used construction adhesive to glue pressure treated sleepers to a concrete basement floor. The glue acts as a vapor barrier and the floor is still in perfect shape after 20 years. On the sleepers I put 3/4 inch tongue and groove particle board, on that 1/8 inch luan plywood and then asphalt tile. I don’t own that house now. I do like your idea of using heavy felt.


-- -- Cheers, Don K. (Michgan's Kewenaw peninsula)

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Jim Finn

2878 posts in 3984 days

#6 posted 01-07-2014 03:32 AM

I have tongue and groove plywood just laying on my concrete floor with no problems here in this high desert.

-- No PHD just a DD214 Lubbock Texas

View doordude's profile


1085 posts in 4045 days

#7 posted 01-07-2014 03:44 AM

I have an epoxy coating for my concrete floor. looks great too. but I have dropped a chisel or two. and I hate it, cuz, its time consuming to put that edge back. Anyway I was thinking of laying 5/8 or 3/4 plywood down, and put a few biscuits in just to lock it in from slipping. no more damaged edges.

View wseand's profile


2796 posts in 4103 days

#8 posted 01-07-2014 06:12 AM

I made my wood floor look just like concrete. ;0~.

View Alan72's profile


222 posts in 3095 days

#9 posted 01-07-2014 07:02 PM

I also thought about putting a plywood floor down in my garage, but settled for the foam squares from Sam club. Look at Delta-FL, it’s a vapor barrier used in basements to put floors on . Infact this past December I had a patient at work who used this same method in his Barn and side it workout great for his plywood floor.

View bigblockyeti's profile


7214 posts in 2782 days

#10 posted 01-07-2014 07:20 PM

I’m thinking of putting something down, but I’m not sure what. I know at some point I would at least want to be able to park a dirty wet truck on it without doing damage & possibly jacking up a car which produces quite a bit more pressure than would be ok for most plywood. The main reason I’m considering this is I want to put in radiant heat in the floor and 3/4” plywood of some kind would be perfect for cutting a 1/2” path for the tubing. I don’t have a surplus of ceiling height either, so I’d rather not put down something that would take up much over an inch, not to mention it would have to be tapered somehow by the overhead door for vehicle ingress/egress should the need arise. Any suggestions?

-- "Lack of effort will result in failure with amazing predictability" - Me

View Deaner's profile


45 posts in 3148 days

#11 posted 01-07-2014 08:01 PM

Hi Don,

As mentioned in my initial post- I used 3/4” quality plywood to install over my concrete floor. I used 30 lb. felt paper as underlament and vapor barrier.
When cut down to equal dimensions, each 4×8 sheet of plywood yielded 8 squares- 23-3/4’ x 23-3/4” apiece- effectively creating large plywood tiles to free float on the underlament.

I created a jig to rapidly and consistantly place and cut 4 biscuit slots (size 20) on each edge of each tile. Yes, that is one buttload of buscuits, a lot of heavy sheets of plywood, and a numbing amount of time at the tablesaw perfectly cutting all tiles exactly the same length.

Why not use full T&G sheets? Well- I guess you could. I was concerned about the larger surface area of a full 4×8 sheet and the tendency to cup at that large of a piece. Smaller tiles also allowed for easier placement around irregular obstacles like my workbenches and other things like doors and a fireplace.

It took me 12 full sheets to complete 1/3 of my 30×40 shop. I still have 2/3’s to go. :-/ Woo-hoo, huh?
But I will put down my second 1/3 of the floor this Spring after some other projects get wrapped up.

I then put down a hard flooring polyurthane finish that is rock hard for protection.

It all looked brand new and pretty. Now it looks like a shop floor with all the wear that goes with it. It is holding up very well. I expect it to hold up for the rest of my shop days. A few of the tiles have slightly cupped, but not bad at all. A few of the seams creak like any old wooden floor when walked upon…but thats cool with me. I like my floor and will be glad to get it finisished. What I don’t like is moving a tons of tools to get it done:-/
I will post pictures sometime soon if you are truly intersted, or you can email me at [email protected]

Good luck and happy New Year!

-- Once harm is done, even a fool understands it.

View comboprof's profile


277 posts in 2796 days

#12 posted 01-08-2014 01:13 AM

Thanks Dean for the update.

-- -- Cheers, Don K. (Michgan's Kewenaw peninsula)

View ferstler's profile


342 posts in 4582 days

#13 posted 01-08-2014 01:20 AM

Garages are for cars. Cars cost too much to leave outdoors. Build a shed out back for your shop.

View Shawn Masterson's profile

Shawn Masterson

1325 posts in 3010 days

#14 posted 01-08-2014 02:18 AM

Ferstler – you are nuts. cars live outside. outside at the dealer, work, well everywhere but at your home. o wait my truck is under 30” of snow right now. well at least my $40,000 worth of tools are warm and dry, and I don’t have to move my tools at the and of the day. as for a shed?? I have a 26×30 and I don’t think its big enough.

View garlandkr's profile


58 posts in 2566 days

#15 posted 12-29-2014 02:52 AM

Would like to give this a go, my garage is under the house and is a miserable 7’ tall, the lowest point where a beam runs through is 73” and I’m 72” tall. Adding the floor would cause many a headache, not just for the installation but for the days I forget to duck.

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