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Login to post Forums » Off-topic discussion » Hardwood on concrete slab?

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Sept. 6, 2011 7:04 a.m. alfadriver SuperDork

This is a good discussion.

One thing I think I can tell for me, up in the north, gluing wood is a bad idea. And not due to the concrete curing issue, but just due to ground moisture.

While they exist, it's pretty rare to find homes without basements, so most situations where one would put wood over concrete has to deal with probable water pressure pushing up through the floor. So IF (and that's not likely to happen anyway) I were to put a floor in my basement, I would float the wood.

But I can see the installation in places like Texas, for sure.
Sept. 6, 2011 8:27 a.m. pinchvalve SuperDork

My wife is the flooring expert (Ardex/Henry Cements) but I saw something in Home Depot which may be helpful. This is designed to be a subfloor over concrete, even if you have water intrusion: DRIcore

Never used it, but I may try it on a small scale in my basement in a bathroom under tile.
Sept. 6, 2011 8:31 a.m. spitfirebill SuperDork

The wood flooring in a portion of my daughters house is glued to the concrete slab. We had to replace it because of water damage from a leak at the sink. While being replaced, the installer, who was really good, told us it could be glued or floating. He didn't advise us one way or the other and floatng would have been a lot easier for him.
Sept. 6, 2011 9:07 a.m. slefain SuperDork

Not sure how common this is, but when we redid our enclosed garage it has glued down parquet flooring that would NOT budge. We left it in place, put down 3/4" plywood with cut nails and then laid staple down pre-finished hardwood on top of that. It raised the floor a good 1.5" but man is it solid and feels great to walk on. Overkill tough I'd bet.
Sept. 6, 2011 9:14 a.m. Otto Maddox Dork

I know what does not work - self adhesive vinyl. I was pulling those up in my basement yesterday. Most of them were really loose.

I was thinking ceramic tile for my new floor but once that stuff is down, you just about need a jackhammer to get it up. Plus, tile cutting, adhesive and grout is super messy. And maybe it is just me, but my tiling jobs never look as good as those of the professionals.

After reading through all this, I am really leaning towards a floating engineered floor and maybe tile in the bathroom.
Sept. 6, 2011 9:54 a.m. dyintorace SuperDork

Our house was built in '99 on a slab. When we remodeled in '05, we took up the carpeting and put down engineered hardwoods I bought from Lumber Liquidators. Given that we lived in the house during the construction (not fun in general), I witnessed the flooring install. The wood was glued directly to the slab. 6 years down the road = no issues. And we lived in hot/humid Gainesville, FL.
Sept. 6, 2011 12:45 p.m. SVreX SuperDork

slefain wrote:

Not sure how common this is, but when we redid our enclosed garage it has glued down parquet flooring that would NOT budge. We left it in place, put down 3/4" plywood with cut nails and then laid staple down pre-finished hardwood on top of that. It raised the floor a good 1.5" but man is it solid and feels great to walk on. Overkill tough I'd bet.

Parquet flooring is commonly glued to concrete.

The issue is the actual size of each of the wood pieces. Parquet is typically perhaps 1"x 3" pieces only 1/4" thick.

That's not much wood to expand. Besides, if it did, cracks between pieces are very much a part of the look.

Additionally, it is essentially an engineered floor. There is a lot of metal and glue holding those tiny pieces of wood to each other.
Sept. 6, 2011 12:51 p.m. SVreX SuperDork

There is one important distinction that has not been well made in this thread.

What most people call "wood" is actually pre-engineered flooring. Sometimes it is laminated, veneered, composite, etc. but it is frequently NOT actual wood boards.

Almost everything you will find at Lowes, HD, or Lumber Liquidators (which probably covers 80% of the market) is engineered.

Many of these engineered products are suitable for direct glue down. (check with manufacturer)
Sept. 6, 2011 1:11 p.m. carguy123 SuperDork

Here is what one of my builders had to say about it

"We use real wood. Depending upon if it is glue down or nail down determines what precautions are taken. Nail down has a vapor barrier we put down and has to cure in the house for a week before finishing. Our wood is under our std. warranty and some have ext. warranties on finish."
Sept. 6, 2011 1:19 p.m. monark192 Reader

I glued an engineered wood floor to our place about 10 years ago with no issues. I'm in So Cal so fading from the sun is more of a problem than moisture though. The glue was a bit of a nightmare to work with - stuck to everything and I still have tools with it on.
Sept. 6, 2011 1:31 p.m. Otto Maddox Dork

In reply to SVreX:

Yeah, when I say wood, i am thinking like just like from a tree, not the plywood, veneer, engineered stuff.
Sept. 6, 2011 1:44 p.m. SVreX SuperDork

How do you nail to concrete?

Carguy123, I'm not trying to be argumentative, but your response reinforced my point.

The vast majority of builders use 15# building felt as a "vapor barrier". It doesn't meet the Federal guidelines for perm ratings for vapor barriers.

Article on building felt

Case study on building felt failure as a moisture barrier

Additionally, allowing the wood to "cure in the house for a week before finishing" is NOT in keeping with most manufacturer's recommendations, nor with the recommendations of the National Wood Flooring Association. In fact, it might be a detrimental practice.

NWFA Recommendations for acclimation of wood flooring

Article on proper acclimation

I mean no disrespect, but your builder friend is not familiar with the building codes or the manufacturer's guidelines.

I'm glad it is working out for him, and hope it continues to. But if there were ever an issue that ended in court, he would be paying that warranty claim out of pocket.
Sept. 6, 2011 2:55 p.m. carguy123 SuperDork

SVreX wrote:

How do you nail to concrete?

Carguy123, I'm not trying to be argumentative, but your response reinforced my point.

The vast majority of builders use 15# building felt as a "vapor barrier". It doesn't meet the Federal guidelines for perm ratings for vapor barriers.

Article on building felt

Case study on building felt failure as a moisture barrier

Additionally, allowing the wood to "cure in the house for a week before finishing" is NOT in keeping with most manufacturer's recommendations, nor with the recommendations of the National Wood Flooring Association. In fact, it might be a detrimental practice.

NWFA Recommendations for acclimation of wood flooring

Article on proper acclimation

I mean no disrespect, but your builder friend is not familiar with the building codes or the manufacturer's guidelines.

I'm glad it is working out for him, and hope it continues to. But if there were ever an issue that ended in court, he would be paying that warranty claim out of pocket.

I've gotten virtually the same info from 3 builders in the area. As far as nail down vs. glue down the difference has to do with the effect you want to present and differing room levels. Nail down requires they glue down wood (usually plywood) and then nail down a thinner board than the glue down boards.

Nail down is seldom used. I haven't heard back from any of them as to what they use for the vapor barrier.

The curing for the week is to make sure the wood is settled and therefore doesn't move slightly and cause cracking at the board junction after the finish is applied.

I'm told they are following manufacturer recommendations of both the wood and the finish.

As I said before, the proof is in the pudding and not only have I personally seen it work well, but there are thousands, if not tens of thousands of homes in our area using the technique plus several others from other parts of the country have chimed in with good results as well.

I wouldn't hesitate to do it my own home.
Sept. 6, 2011 3:03 p.m. Otto Maddox Dork

I wouldn't trust a builder's opinion over that of the product manufacturer.

In fact, I wouldn't really trust a builder's opinion about much. They've done too many cheap, stupid, crappy things in the houses I've owned.
Sept. 6, 2011 3:24 p.m. SVreX SuperDork

I don't think you have to trust anybody's opinion.

Read the links I supplied. They are from the associations that offer the guidelines for the manufacturers, and the actual code enforcement agencies.

It's really not a matter of opinion.
Sept. 6, 2011 3:31 p.m. SVreX SuperDork

Since damaged floors mean more work for me, perhaps I should say it is a great idea!

I'll admit I have not witnessed much damage related to a glue down installation. It is ultimately the owner's choice.

But manufacturer's guidelines exist for a reason. I absolutely guarantee the manufacturer will NOT stand behind any installation that is not in keeping with their guidelines. They LOVE it when builders or owners don't play by the rules so they don't have any product liability exposure.

If I ever had to call for warranty work, I'd rather the weight of the manufacturer standing behind the installation than a small time builder who might not even be in business when the warranty call is made.

I respect your opinion, carguy123. But I am a little surprised hearing it from a mortgage broker. You guys are not known for overriding codes and specifications with opinions when there are liability issues at stake.

I have 35 years experience and have never had a single callback for any failure. I like it that way.
Sept. 6, 2011 3:32 p.m. carguy123 SuperDork

Otto Maddox wrote:

I wouldn't trust a builder's opinion over that of the product manufacturer.

In fact, I wouldn't really trust a builder's opinion about much. They've done too many cheap, stupid, crappy things in the houses I've owned.

But they are the ones who have to foot the bill when they install something wrong so they don't things wrong on high ticket items like wood floors. That's a lot of labor to remove and replace.
Sept. 6, 2011 6:59 p.m. RX Reven' Reader

FWIW, I installed 820 sq ft of engineered wood in my last home six years ago and it’s in perfect condition despite spending half of its life under renters. I’m in California so this may not be highly relevant but I did a floating installation after letting the wood acclimate to the environment for two weeks and I had a cement slab that tested out with moderate but acceptable moisture levels.

I started with 12X12 self adhesive vinyl squares I bought from H.D. for $0.19 each. I know this is highly unorthodox but their cores are made of tar so they serve as an ultra cheap and convenient first layer of defense against moisture. Also, their glossy surface makes any irregularities in the slab very obvious and should the hardwood floor every need to be removed, there’ll be a brand new serviceable covering on the floor ready to go. Next, I used the best matting available which was very dense and came with an aluminum foil backing.

Easily 80% of my time and effort was spent on preparations so if you’re fortunate enough to be starting with a good surface, it’ll be an easy job.
Sept. 6, 2011 7:32 p.m. Hal Dork

The wood floor in our family room is glued to concrete and has been installed for 10 years now with no problems.

INFO:

The family room was originally the back porch and had been for 3 years before we enclosed it.

The family room had been enclosed (heated and air conditioned) for 5 years with glued down carpet before we put down the wood floor

The wood is an engineered (laminated) product. Got estimates from 5 different companies to do the floor. None of them would glue down a solid wood floor but each had an engineered product they would do. They all insisted that I do a condensation test before they would put down the floor.
Sept. 6, 2011 8:11 p.m. Curmudgeon SuperDork

I should have clarified at the outset that I am looking at engineered flooring. I'm staying away from the low end stuff and the very high end since wood flooring is susceptible to gouges etc and it would absolutely tear me up to see furniture dragged across high end solid flooring.

Also down here basements are VERY rare, slabs are usually either flat on the ground or are raised slabs. It's basically a 'ring' of cinderblock with brick veneer or similar outside, the center is filled with that yellow fill sand, this is tamped down solid and then maybe 4" of concrete is poured over that.

This is a real good discussion, I'm learning a lot!

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