View Full Version : Installing Hardwood on a Slab Foundation

Dan Mages
11-15-2008, 2:40 PM
Good afternoon,

My Father-in-Law wants hardwood flooring in the dining room. The house is on slab (Dallas area). He looked at options and thinks solid hardwood with clips is the way to go. I do not know much about this system. Does this system work well? Any other options to consider?


Matt Ocel
11-15-2008, 4:57 PM
Solid hardwood over concrete is a very difficult install and very risky.

Difficult because, solid hardwood may come out of the box bowed, I have never used nor do I know about the clips, so I don't know if the clips would be strong enough to take out the bows.

Risky, simply because of the potential failure due to moisture.

As a licensed contractor, I would never install Solid hardwood over concrete. Never!

If conditions were perfect, and a client absolutely wanted it, I would think about installing an engineered floor, But I would not guarantee it.

Greg Cuetara
11-15-2008, 6:07 PM
Not sure if this would work or how expensive it would be for you but when I was looking at installing radiant heating one of the contractors told me to lay down 2x4's at 16 - 24 inches on center. Then for the radiant they would infill between the 2x material with the radiant tubes and a mud mat of lean concrete / morter mix. The 2x material would give something to nail the hardwood flooring to.

You can take 2x material and fasten it down to the concrete slab with concrete fasteners and then nail the hardwood flooring to the 2x material. You would probably have to infill between the 2x material with something to keep the moisture out from under the floor.

May other's can chime in if this is a good or a bad idea.

I would think you might be best off with an engineered floating floor system but there has to be a way to make it work.


Dewey Torres
11-15-2008, 7:22 PM
I am not a flooring expert but I had a slab at my old house in VA and it had a floating hardwood floor (real wood not laminate). I think this is the application you are looking for:


My floor was the Bruce "lock and fold" type.

Matt Ocel
11-15-2008, 7:42 PM
I am not a flooring expert but I had a slab at my old house in VA and it had a floating hardwood floor (real wood not laminate). I think this is the application you are looking for:


My floor was the Bruce "lock and fold" type.

FYI, A Bruce "Lock and fold" would be an engineered floor. It is real hardwood veneer, but not solid hardwood.

Laminate = Plastic

Ken Garlock
11-15-2008, 8:08 PM
Hi. We considered hardwood flooring when we built. Our contractor said that for real hardwood, it would be necessary to install a 3/4 plywood underlay for the hardwood to attach to. We decided that carpet was a better choice, both cost and maintenance.

Everything is slab in North Texas due to the black gumbo clay soil that expands and contracts with the rain fall. No rain, it cracks, cracks big enough to put you arm in up to your elbow. ( you don't do that unless you want to meet up with a snake or a tarantula) When it rains, the same soil get very sticky, you would think you have half your yard on your shoes. All in all, the soil makes it a crummy place for a city.:)

45 miles north of Dallas.

Steve Evans
11-15-2008, 9:35 PM
Google "elastilon". It's been used for a few years over in Europe for this exact scenario. Some solid flooring manufacturers are warrantying solid below grade using this product. Not associated with them in any way, yadda, yadda, yadda, just had a chance to play around with it recently and it looks extremely promising

Richard Argentieri
11-16-2008, 7:53 AM
I've had some experience with various slab systems. For what it's worth, here's my summary:

Floating Floor with Clips
I installed solid hardwood (Brazilian Cherry) on a slab using a floating system with clips in Atlanta GA. If you choose to go this route, go with a foam moisture burrier to avoid the metal clips "clicking" against the floor.
- The final installation will be relatively low requiring less door shaving and nicer transitions.
- Doesn’t require any special tools for installation
- As with any floating system, the floor will have some "give" (or as my wife would say “squishiness”). This doesn't bother some people. I grew-up in Buffalo where a lot of people had basements or crawlspaces so I'm used to the solid feel of nail down installations.
- There will be some creaking due to the aforementioned give.
- (IMHO) It much much slower than nail down installations, and to install the clips will be spending all that time on your knees.

Sleepers with Staples
I’ve also installed solid hardwood on slabs using a sleeper system and a tongue nailer. These are great because the air movement keeps them dryer and you’ll even save some money on material over solid plywood method. I used to work for a contractor in Niagara Falls, and they installed a dance floor over a slab below grade in a church basement 20 years ago, and it’s still in great shape.
- Rock solid
- Quick and back saving installation with a pneumatic tongue stapler
- Mitigates moisture problems
- It sits higher than a floating or glue down installation and transitions are important to concide. I just use a reducer, and have had great results.
- Need a compressor, tongue nailer (rent), and finish nails for the first and last row where the tongue nailer can’t reacj.
Latest Job
I just finished a solid oak installation here in south Florida using a sleeper system. Since I tend to get a lot more questions about these, I thought I’d do a quick walk through.
Start out by laying a moisture barrier (ex builder’s felt, or poly film) over the slab. Next lay ¾”x4”x4’ sleeper strips 12” on center using a powder actuated nailer. (Nail every 6-12”) Do NOT lay the sleepers end to end, overlap them, so they can move without cupping. Some people will tell you to lay another moisture burrier over the sleepers before laying the hardwood. I’ve done it both with and without and didn’t notice a difference.

Finally lay the hardwood perpendicular to the sleepers nailing them down with the tongue nailer. As with all hardwood installations, be sure to leave .5”-.75” gap around the room for expansion.
Plywood subfloor installations are essentially the same, but you cover the entire floor after the moisture barrier.

Hope that helps....

Matt Ocel
11-16-2008, 8:29 AM
Richard -
Very nice explanation.

Dan Mages
11-17-2008, 11:56 PM
Thanks for all of the great advice. I think I have convinced him to step away from the clips and go with an interlocking floating veneer style wood flood. I have one in the lower level of a split level ranch I own and it has so far worked fine on a concrete slab... Now to get the mother in law to choose a colour....