Solid wood floor over concrete slab?

[mark mcfarlane]

Marion's pine floor has me drooling.

Anyone put a solid wood floor in their shop over an on-grade concrete slab? Zone 1 (humid south Texas). What did you put under the wood floor? Stringers? Insulation? (Floor insulation probably isn't big deal in south Texas). 34'*28' shop will be heated and cooled.

Ever drive a pickup truck over the floor?

Considering the cost of contracted high-solids epoxy and/or good rubber flooring,....

[Chris Damm]

We had a hickory wood flour installed in our house over a concrete slab. They used an adhesive that acts like a vapor barrier. It is very humid here and so far no problems. We went and looked at the same floor in the store owners house a couple of miles away and it still looked great after 8 years on a slab. I have 1/2" rubber mats in my new shop. I brought them from my old shop in MI.

[Jim Becker]

Ideally, you want a moisture barrier, sleepers with rigid foam insulation between and then your subfloor. The sleepers can be just PT 2x2 (1.5" thick) so there's minimal effect to head-room. If you spaced narrow enough for good weight distribution you might be able to pull a vehicle on between the sleepers, insulation, subfloor and floor surface.

[Roy Harding]

I put my shop floor over the concrete, first laid vapour barrier, then the sleepers - I used 2 X 8's for sleepers so that I could run my dust collection piping under it. I insulated (I'm somewhat further north than you, and insulation was a prime consideration). I then used 3/4" tongue & groove ply as a subfloor.

I had INTENDED to put down an engineered wood floor, but that was eight years ago and I haven't got around to it yet. Considering the number of shellac and glue spills that have taken place over the years, not to mention the dropped chisels and other tools, that may actually be a good thing.

The raised floor was an afterthought - AFTER I had built the shop, so at the doorways you step onto the concrete, and then step up into the shop - this has actually worked out very well, as the cavities at the doors act as "cold sinks" in the winter, letting the cold air fall off the raised floor - keeping my feet warm, even when opening and closing the doors a lot. It did cut down the head space a bit - I had 10 foot ceilings planned originally, but there's enough headspace left that I can carry a sheet of plywood vertically without any problems. In retrospect, having less head space has probably made keeping the shop warm in winter somewhat easier/cheaper (a problem you don't have in your location, but perhaps it would affect air conditioning in a similar manner?)

I don't think I'd want to drive a truck on it - but my sleepers are at 24" o.c. - as Jim suggested, if you spaced them narrow enough you may be able to do it.

[Jim Andrew]

I am in the process of laying wood over my concrete. Already had some 1" dow board, r factor of 5, so just bought some treated flooring, and ripped it down the middle for sleepers. I used tap con screws to hold the sleepers in place, cut the dow board to fit between the strips, then am laying some fir flooring I salvaged from a church that was to come down. My floor would stay dry when I laid down a sheet of plastic, so did not bother with a vapor barrier under the strips. The dow board acts as a vapor barrier. Will have to take my walk in door out and raise it so I can open it,and at the garage doors, just plan to make a frame, caulk under it as I screw it down, to try to keep any moisture out from under the floor, that might come under the garage door.

[Chris Parks]

I have a two story workshop and both have 19mm sheet flooring and the top used to be my garage so cars were on it every day. The bottom floor is a concrete slab with 4 x 2 hardwood joists topped off with the sheet flooring and the top floor is a steel structure with the flooring screwed straight to the steel joists. Both have been down over thirty years with no issues.

[roger wiegand]

I put vapor barrier and 2" of blue foam under the slab, on top I used 2x4's on the flat as sleepers, then subfloor and site-finished hardwood for the floor ("mixed domestic hardwood" for cheap from my flooring supplier-- about 10 different species. Looks pretty cool!) Almost four years now and everything works fine. Finished with Bona Traffic HD-- amazingly tough finish.

[Mike Wilkins]

Search the FineWoodworking site for help on wood floors over concrete. Involves a plastic vapor barrier, treated lumber, foam sheets between the sleepers, and then 3/4" tongue and groove plywood on top. Should be a lot easier on the feet and warmer than concrete.

[Robin Frierson]

I have put two ply wood floors in shops before. I tapcon 2x4 on 16 inch centers. I use no barrier , no insulation just put the sleepers down with adhesive. I made sure that there were pieces of wood under all plywood joints. Do not leave any joints unsupported. When it was done I could drive my truck on it with no problem. If you really want to make it strong use two sheets running opposite directions. That's what I did on my first floor and it was an inch and a half thick. Overkill, but it still there today over 20 years.

The first plywood floor I finished with Polly and it was slippery when covered with dust. My second plywood floor I put no finish at all on it and that's the best way to go. We all want to do something to the floor but the best thing is to do nothing and leave it natural. I'm currently in my third shop working on concrete and I hate it. I do plan to put in another plywood floor. Unfortunately my knees are so bad I can't get down now so I'm gonna have to hire someone to do it

[Brian Backner]

You could do what I've seen in numerous old factories in New England. Install short blocks of (ideally) white oak on end glued directly to the floor. With the grain oriented vertically, such a floor wicks moisture very well and does not rot. I went to a factory auction once where there were a lot of machines for sale in the 5-20 ton range. The floor was made up of 16 or 18" long pieces of white oak 2x4 glued to the floor - N.B. do not glue the 2x4s to each other or you'll never be able to replace a damaged one - and the highest price paid for anything that day was for the floor! With something like 120,000 square feet of 16" thick oak, the eventual buyer harvested it all, cleaned up the oil and grease impregnated top by cutting off several inches and sold them all to a company making some kind of wooded doodads.

The advantage to this kind of floor is that it is mega strong - rolling 20 ton machines across it is no trouble. It can handle forklifts, cars, trucks, you name it. It is also easy on the feet/legs/back and if you drop a sharp edged tool, there's a good chance it'll stick in the floor rather than bounce off and chip the edge like would happen on concrete.

I had a friend years ago that did this to his basement shop using 3" blocks of common 2x4's. He loved it, but I haven't talked to him in nearly twenty years since I moved, so I have no idea how well it's stood the test of time.

[Jerry Olexa]

I reco sleepers and a vapor barrier..

[Richard Barker]

I laid down Delta FL over the concrete, then 5/4 advantec with 1/4" plywood running perpendicular. Over this we nailed 3/4" tavern oak. This floor floats and is not attached to the concrete underneath. this was two years ago and I have had zero problems with this installation.

[Michael Stockdale]

What is Delta FL??

[Adam Herman]

it is a sheet vapor barrier product.

[Michael Stockdale]

Did you glue the advantec edges together? What about the 1/4" ply... is it glued or adhered somehow to the advantec? This method sounds very attractive to me... I don't have the headroom for sleepers, but 1 1/4 of ply flooring I could probably do.