Wood shop floor over concrete

[Wooden nickel]

Hey guys,
I am finishing my sys cabinets for the garage.
It is a concrete floor.
I have the little lip step up/ slab on one wall that is the “dry” area.
This is where the cabinets will go.
Question to anyone that can help;
I want to put a wood floor there in that section and want to know if
I put down plastic, treated sleepers, rigid foam in between and then plywood?
Or is it treated sleepers, rigid foam, then plastic, then plywood?
Also- when laying down the sleepers, should they be gapped from the wall sheathing or tied in directly to the bottom sill plate? 
Or keep the entire floor gapped/ separates from the walls?
Any help is appreciated. 
If it has any influence, I am in the Houston ( high humidity) climate.
But the shop is enclosed and air conditioned.
Thanks,
Scott

 

[Brice Burrell]

Scott, there are a lot of options.  If you have puddling water you need to solve that problem first.  If your floor is truly 100% dry, all year round, you can put a wood floor directly on the concrete.  If your floor has a small amount of moisture coming through you could go with a vapor barrier they a click together floor on top of the concrete (padding optional).  Even with padding many floors directly on the concrete tend to feel like concrete on the feet. 

If you think a sleeper/plywood floor is the rout to go you'll need to think about elevations, doors thresholds and maybe even head room. There is some debate about what goes down first, the sleepers or vapor barrier.  Some believe you glue and fasten the sleepers to the concrete then the vapor barrier, other think the barrier first.  You can't glue the sleepers if the barrier goes down first.  BTW, put the vapor barrier down even if you believe your floor is dry, its cheap insurance.  No need to attach the sleeper to the walls.  I happen to think insulation in the floor is optional, if you have the budget go for it.               

 

[Wooden nickel]

Thanks Brice,
Good info.
The floor is dry, even after a hurricane and bad flash flooding.
But there is the normal moisture that seeps from concrete slabs.
The area is not too big, so I will go with what you said about vapor barrier and ply.
I just don’t want to see my cabinets suffer.
But if the ply starts to turn I can always pull it up and go full route with epoxy or build up a floor that will resist moisture from concrete.

There isn’t going to be a heavy load on that area, so no equipment or anything to support.
So is the rigid foam more for insulation or for moisture along with the vapor barrier?
Or both maybe?

 

[Brice Burrell]

Assuming your sleepers have good contact with the concrete you don't have to worry about weight.  You could use as little as 3/4" (1x material laid down on the floor) sleepers, but 1 1/2" (2x4 flat on the floor) might be better. I'd use masonry screws (Tapcons or Red Heads) or shoot it down with a powder actuated nailer (Ramset). 3/4" plywood on top, preferably tongue and groove.   

The foam is for insulating.

 

[rvieceli]

[member=65661]Wooden nickel[/member]

If you are wanting to have an area with a wooden floor in your garage then Brice's suggestions are spot on. If however, you merely want to keep the bottoms of your cabinets from having direct contact with the concrete floor, you might want to consider using a couple of pieces the composite decking material like Trex or one of the cheaper brands. Lay or tack down a piece on the floor at the back of the cabinet and then another one at the front of the cabinets. Those will support the cabinets and keep them off the floor and dry. The plus is the air space between the two strips will add some ventilation and you'll only raise the actual cabinets by about an inch. Plus a lot less hassle.

Ron

 

[tms0425]

I've used Dri-Core 2'x2' interlocking T&G subfloor on top of concrete, with Bamboo flooring nailed down and been very happy with it. Big boxes usually stock it.

Dri-Core subflooring

 

[tjbnwi]

This shop we just finished has a Hickory floor over Dry-Core Plus.

Tom

 

[rvieceli]

Very nice Tom. Is that your shop?

 

[tjbnwi]

Very nice Tom. Is that your shop?

No, created for a client (I think his wife uses it more than he does).

Exterior of the shop.

Tom

 

[Cheese]

Nice shop both inside and out. All new equipment also... [cool]

 

[Cheese]

A number of years ago I placed 6 mil poly on the concrete, then cut sill sealer into 1 3/4” widths. Laid the sill sealer down on the poly with treated 2x2’s on top of the sill sealer. Fastened everything to the floor with Remington loads. Kept the sleepers short of the drywall so the poly could be wrapped up the drywall about 2”-3”. Placed 1 1/2” foamular between the sleepers and covered the whole thing with 3/4” T&G ply.

Everything is still fine...however I don’t know for sure because the floor has never been ripped up. Sometimes you just don’t know what you don’t know.

 

[Wooden nickel]

Tom,
The shop looks awesome.
That dri-core looks interesting, and I would definitely use it if my garage shop could justifiy it. 
I left the web page open for future projects
Maybe when I actually make money woodworking instead of spending it 
At this moment I will go with what cheese and Brice said and lay poly, sleepers, then ply.
Not sure if the rigid is needed in this climate, probably useless on the floor.
I will attempt it this weekend and post photos on account I could not find too much info online.
It won’t be anywhere near Tom’s floor, but I’ll do my best. 
Scott

 

[Bob D.]

I calculate my 24x24 garage space would take about 175 DRIcore panels and cost about
$1000. It goes down much faster and less labor than other systems and has a R value of
1.7 . You only need a saw for cutting panels and a rubber mallet for knocking the panels
together and depending on how level your floor is maybe a couple shim packs which are
about $5 each.

With DRIcore it's less than a day to install. I plan to do this in the two bays of my
garage that I have converted into my shop. I only wish I had done it years ago BEFORE
I setup shop. Now I have to move everything out or shift it around in the shop so I can
cover a section of floor at a time. I then plan to cover the DRIcore with a wear surface,
I am thinking of plywood but haven't decided yet.

 

[Tinker]

Brice pretty much covers most of the problems in posts #1 & #3. My shop floor ws installed over very unlevel concrete. I only put down 15# felt and then used pressure treated 2x3 on their sides, pressure treated 1/2" ply over and then 1/2" CD ply over that. Any knots, i just troweled over with joint cement and placed vinal tiles for finish. The floor is still not level, but even tho I used no vapor barrier other than an air space and the pressure treated plywood, there is no sign of moisture wicking from the concrete. None of the tiles show any curl. The floor is solid for any machinery I have in the shop.  The heaviest machine is my bandsaw. I have it on rollers.  There is no flex or bounce when I move it.

About moisture wicking thru a concrete floor:  I know from experience that even tho concrete appears to by absolutely dry, there is enough moisture wicking, either from soil below, or  from humidity of the air, if a bag of cement is placed on the floor for storage til use, it will harden within a couple of weeks. If the whole bags(s) don't harden, there will still be lumps.
Tinker

 

[tjbnwi]

For those considering Dri-Core, if you go with a staple down floor you have to use 3/8" plywood over the Dry-Core. This layer prevents the staples from penetrating the plastic backing.

Tom

 

[antss]

How much of a step down are you going to have when you're all finished

I'd be concerned about the final level so it's not a trip hazard when stepping down.

 

[Jungle8888]

you could use something like Delta FL or similar and put pressure treated plywood on top, that way if there is any water issues, it'll just evaporate.
Dricore has osb on top and it that gets a little wet, it'll just swell up