View Full Version : Putting Down Heart Pine Floors over concrete..

05-12-2005, 10:43 PM
Ok, most of you here are wood guru's...at least you are wiser than I. And I figure most of you have certainly taken your boat skills to your home, or gone from home to boat...anyway...

Here's the situation:

My house is 15 years old. Concrete slab about 18 inches above ground.

I want to put down Heart Pine floors.

The builders I have spoken with here in my area (southeast Ga.) have told me that the moisture should not be a factor on a slab this old. One even said, glue the wood directly on the concrete.

Putting down 3/4" ply subfloor over a moisture barrier then 3/4" pine on top of the ply sounds like the best solution but it raises the floor up 1.5 inches. This does change things a bit, especially in the kitchen for example regarding the existing cabinets and kickplate area under the cabinets - narrowing the recessed kickplate base of the cabinets.

Is raising the floor 1.5 inches really that big of a deal?


1. Your thoughts regarding 15 year slab and wood flooring...hear are the options...

option 1: moisture/vapor barrier, 3/4 ply subfloor (liquid nailed? or tapkon? to concrete), 3/4 pine boards: the 1.5 inch rise is not the big a deal

option 2: 3/4 inch pine planks liquid nailed or 5200'd (if 5200 works on concrete) directly to concrete slab (I could treat the underside of the planks by applying Smith's CPES

Thanks in advance


John Bell
05-12-2005, 10:58 PM
My parents put oak down on their slab about a year and a half ago. They went the 3/4" ply underlayment route. About 8 months after it went in, the whole floor buckled and pulled up from the slab when it got a little damp due to some faulty carpentry when they had the house re-sided.

The ply underlayment and the flooring had been set too tight in the room. There wasn't enough of an expansion gap at the edges. The ply was nailed down to the slab with a Hilti gun, and the nails pulled right out.

After a lot of back and forth with the various parties, Dad got someone to agree to put in another floor at no cost to him. But he did pay extra this time for the subfloor to be screwed down with expansion anchors. Some poor guy had to drill about 200 holes one day with an impact drill.

So far so good with the re-do.

One thing Dad didn't do was rip off the baseboards for the 1.5" thicker floor. They simply nailed quarter round to the existing baseboards, and it frankly looks terrible. The loss of floor to ceiling height is not noticible otherwise. But be warned if you do it in kitchen, because you'll certainly notice your counters being lower.

05-13-2005, 06:30 AM
The concrete won't be trouble, the wood will be as it expands and contracts from moisture changes between winter and summer. Furniture has the same problem if you tie things down cross grain. If you were putting a stable material like sheet flooring down, you would not have trouble with moisture from the concrete. I'd suggest a floating floor for this application so the material could expand and contract as a unit over the concrete.

05-13-2005, 07:42 AM
I'd go with option #3. Vapor barier, 3/4" firring strips 12" on center nailed into the concrete. 3/4" pine over that. The firring strips will allow air flow between the concrete and the floor reducing the amount of moisture build up. It will also allow more movement in your flooring.

Paul Denison
05-13-2005, 08:02 AM
Seal the concrete first, then moisture barrier. Make sure you let the wood adjust to local conditions for a couple of weeks. Ask me how I know this? :( Wood from the kiln is much drier than your house. The boards will expand across their width and if nailed properly will push up at the joints.

[ 05-13-2005, 09:05 AM: Message edited by: Paul Denison ]

05-13-2005, 08:27 AM
We have gluedown prefinished wood flooring over concrete. I don't remember about the vapor barrier under the wood but there is one under the concrete. The prefinished flooring is real wood, three 1/8th plys, no plywood under or firing strips. It has been down a year and we have had no problems. The RH in the house has varied from about 35% to 75%.

05-13-2005, 09:10 AM
Thanks All, very much!

A couple of follow up Questions...

FG, you mentioned a floating floor. I assume, therefor, I had better make the planks tongue and grooved? I have no problem doing that, just making sure! Thanks!

Mrleft8, I like the fur strip idea, saves a little more vs. 4x8 t&g subflooring if I go that route. Question, would the gap cause the boards to sag over time? Or is a 12 inch gap tight enough?

Paul, didn't realize there was a concrete sealer out there. Duh! Obviously, I am a newbie at some of this stuff. :rolleyes:

Again, thank you all for your help.


05-13-2005, 10:14 AM
I put down random width heart pine throughout the living room, dining room, kitchen and love the look. We did put it over a plywood subfloor so no issues with concrete. What are you going to seal it with? We used velvit oil and like the look.

Bruce Hooke
05-13-2005, 11:15 AM
It sounds to me like the right way to do it is going to be a real pain in the you know what because it will mean removing the kitchen cabinets and the baseboard trim. You may also have problems with the doors -- if they are frame and panel then cutting that much off the bottom will likely leave them looking trimmed, and if they are hollow core then trimming that much off the bottom may get you too close to the hollow core. Raising the doors would, of course, get into removing drywall so that you can adjust the headers. Then the tops of the doors will not line up with the windows (of course they may not now, but it fairly common to have them line up). If there are stairs that will be another issue because you will really notice if one step is 1 1/2" shorter or taller than the other steps.

05-13-2005, 11:52 AM
This is the perfect time to use DriCore Panels. (http://www.dricore.com/en/eindex.htm)

It'a a 2'x2' panel with a vapor barrier and osb subfloor. The plastic barrier is dimpled to form an air gap under the floor for air circulation, insulation, cushioning and noise reduction. The osb (particle board) is dimensionally stable.

They are tongue-and-groove, so the installation is very easy. You should only anchor them in a couple of places, say once at the center of the room, and once along each edge, and leave a 1/4 inch gap around the perimeter for air flow.

They add less than an inch in height and come with a shim kit for leveling. Besides protecting the floor from mositure and water, they make it easier to install the finish floor, and the final result will look flatter.

I put them in my garage workshop, and this weekend they're going in my basement.

They're about $1.25 per square foot, at Home Depot.

Whatever you do, don't put plastic directly down on concrete. Air flow is your friend.

05-13-2005, 08:33 PM
"Mrleft8, I like the fur strip idea, saves a little more vs. 4x8 t&g subflooring if I go that route. Question, would the gap cause the boards to sag over time? Or is a 12 inch gap tight enough?"
12" should be plenty. It's not like you're going to be driving a truck on this floor.

05-14-2005, 07:04 AM
Again, many thanks guys!

CCmanuals, I was planning on using Waterlox Original Sealer/Finish (http://www.waterlox.com/product.cfm?productid=5). Before moving down here to St. Simons, I lived in Charleston for 5 years. This stuff was used on the pine floors of the Charleston Visitors Center. I've seen it and it looks pretty awesome. Take a look (http://www.waterlox.com/showcase.cfm) . The only set back...long dry time.

ljb5...Thanks for tip! A few weeks back, I discovered DriCore on the NET. I then tracked down the folks at Platon, the material under the the chipboard. They are out of Canada as is DriCore I think. Anyway, they sent me a sample of the platon. I found a sourse for the platon. Comes in rolls of 60 feet by 6 feet wide at $250 a roll. The only problem, you have to buy two rolls. And you can then purchase 4 x 8 sheets of chip board to put over it. A little cheaper if you do it that way as long as you have a bigger job so you can use both rolls of the platon. Pretty interesting stuff, simple design, but pretty cool!

Thanks too Mrleft8, no trucks!

Did some more research around here. Spoke to a guy who has been putting down pine floors here for 15 years. He glues T&G pine directly to the concrete slab(older slab not new)using Bosticks and a 1/4 notched trowel (for 3/4" boards)and has not had any problems. Oh well, more to think about.

Thanks again all.I sincerely appreciate all your help.


05-14-2005, 10:36 AM
T&G floating floor over Paul Denison's approach would be my method. Be sure to acclimate the new floor for 2-3 weeks as he says in the room where it's to be used. Skipping this step will be costly. If you go with a ply subfloor, no need to worry about kitchen cabinet height- remove the cabinets prior to the project and replace them afterward. Removing and reinstalling lower cabinets is a cinch after the first one is done. (first one's always a b**ch). Good luck! Heart Pine is beautiful flooring- makes the house glow!