Cover a concrete garage floor with plywood?

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Forum topic by Brett posted 06-27-2011 06:23 PM 3474 views 0 times favorited 5 replies Add to Favorites Watch
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660 posts in 2679 days

06-27-2011 06:23 PM

I’d like to cover the bare concrete floor of my workshop (located in my garage) with plywood. Can I just lay several sheets of plywood edge-to-edge on the floor, or do I need a vapor barrier underneath? Should I use pressure-treated 2×4s underneath the plywood? Any suggestions? Thanks.

-- More tools, fewer machines.

5 replies so far

View chrisstef's profile


17381 posts in 3002 days

#1 posted 06-27-2011 06:43 PM

yes you will need a vapor barrier, concrete will hold moisture and slowly seep it back out again. Id go with the PT stringers underneath with a vapor barrier under those as well. The cavity may allow you to run your dust tubing and electrical underneath as well.

-- Its not a crack, its a casting imperfection.

View Loren's profile (online now)


10380 posts in 3643 days

#2 posted 06-27-2011 06:44 PM

I’d elevate it. The concrete can hold and move moisture which will get
into plywood sitting on top of it. You might want to paint the concrete
with a mold-resistant paint first.

If you can handle the loss of headroom and the step up it can be cool
to run dust collection pipe and electric underneath the floor.

View rustfever's profile


752 posts in 3306 days

#3 posted 06-27-2011 06:45 PM

First, a vapor barrier, lapped and sealed
Second, sleepers, pressure treated shot down to the floor
Third. prime the underside of the ply [ edges and t&G also] to further prevent moisture
Finally, ply, preferable T&G, screwed down
All seam must be loose to allow for seasonal movement
Hold back from walls about 1/2” to allow movement
Cover the 1/2” at wall with a full 3/4” thick ‘Baseboard’
Treat the floor surface to prevent dirt, stains, & moisture from entering

-- Rustfever, Central California

View Keith Fenton's profile

Keith Fenton

328 posts in 2916 days

#4 posted 06-27-2011 06:51 PM

I always thought that most primer doesn’t protect against moisture?

-- Scroll saw patterns @

View newbiewoodworker's profile


668 posts in 2823 days

#5 posted 06-28-2011 01:05 AM

Im not sure what your height requirements are, but I agree with Chris, if you can afford the height, then you may want to put in runners of maybe 4.5”(2×6 ripped) and then the TnG ply… That way you can run stretches of electrical conduit(floor electrical direct to tools) DC stretches, possibly plumbing, etc. I think if you can afford it, height wise and finanically, then you will be kicking yourself if you dont do it.

Definately put a Vapour barrier down first.

-- "Ah, So your not really a newbie, but a I betterbie."

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