Flooring Over Concrete? Moisture Barrier?

Kevin75

Dear expert people:


I have the following project. The client would like me to build the floor up in the room shown in the picture below. The floor is concrete and the walls are stone. The concrete is uneven, so to bring it up a few inches it'll require some patience.



My question is this:

The client wants nailed down hardwood (solid 3/4") as the finished floor. What precautions should I take to avoid moisture problems?

Thanks!

Kevin

MacRoadie

It's not an easy process. I would suggest laying down a sheet vapor barrier after leveling the floor with sleepers then overlain with a structural plywood subfloor (typically the plastic is draped over the sleepers prior to installing the subfloor). That gives you a more dimensionally stable material closest to the slab. This likely will mess up your door/header heights as well as any interface with any adjacent floor surfaces and thresholds.

Some people might suggest sealing the floor, but that can add moisture to the system that could come up into your hardwood too.

Not knowing what's under that slab, how thick it is, etc. You'd be wise to get some vapor transmission tests (calcium chloride domes) to see what kind of vapor push you are getting before you start anything.

Air flow and vapor through the slab are the key concerns.

Krichton

For someone who is in the business of renovating I'm a little suprised at your question. You cannot nail hardwood to concrete. The best option is to either purchase bamboo or engineered flooring and glue them to the concrete after you've leveled it.

Teetorbilt

I'd start with self leveling concrete to get everything level and build up from there. I'm a big believer in sealing concrete and using a vapor barrier, many homes here are just a few feet above the water table.

You can nail directly to concrete. I don't know what is required but I watched a beautiful Dade County pine floor destroyed because it was nailed direct.

__________________
You can't solve you're problems with the same level of thinking that created the problems.

Albert Einstein

PrecisionFloors

You are absolutely positively incorrect. You can install nail down hardwood over a slab, provided you use a sleeper system as already advised above, or a floating sub floor system.

__________________
Precision Flooring
(772) 237-9900
Tile, Hardwood, Laminate, and Resilient
Installation, Sales & Repair - "We do it right the FIRST time"

neolitic

I'm surprised that after "she" wanted you to mutilate "her" concrete (limestone?) benches (surely look like window sills to me), now "she" wants a clueless guy to install hardwood floors with no consideration of any door ways involved?

__________________
Put your location in your profile!
(Sorry....it seems there really are dumb questions)

Floordude

Everything you need to know, is outlined at www.NOFMA.org

__________________
**Education is the key to success. Learn more, earn more.**
http://www.AustinFloorguy.com

MVH

Floordude: Thanks for the great link!

Mike

__________________
Mont Vista Company, LLC
Alpine, Apache Junction, Gold Canyon, and Mesa, Arizona
Apache Junction Builder
Gold Canyon Builder

Jerry T

Dang, some posters are brutal. Would you rather he/she do something without asking first? I don't get the hostility that is prevelant on this board...

Krichton

Carefully read my post again.

MacRoadie

Maybe you should read the original post again while we're all spending quality library time. The OP never said he wanted to nail the floor to the slab, he simply said "nailed down" (as opposed to glued). He did, however, specifically state that he wanted "hardwood (solid 3/4")"; not manufactured flooring or bamboo.

If he does indeed want a hardwood floor, anything less than a sleeper system with a vapor barrier just isn't appropriate.

You guys are arguing apples to oranges.

Kevin75

Apparently I wasn't clear, but when I indicated that the floor needs built up, I meant I would build it up with wood. The hardwood will be nailed to wood sub-flooring after it's built up.

Kevin75

You guys are tough to please! I'm curious what I said that had anything to do with doors? Can I ask you...what doors are in the room? Do they have steps? Are they standard height? In-swing or out? Could they be customized?


Once you all finish arguing about the items I didn't ask for help on, could you please answer the vapor barrier question? THANKS!

Kevin75

Thanks Jerry. Apparently it makes them feel smart.

Kevin75

Thank you MacRoadie, and all the others who actually tried to answer the question rather than insult my intelligence. I already intended to use a "sleeper" system, and simply wanted advice on installing a vapor barrier. I believe my question was answered adequately (by the first post!). Sorry if I got a little bit punchy with some of the replies. It just bugs me when people don't read carefully, or make insinuations about the situation (doors) without asking questions. It's also is a bit irritating when guys mock you with regards to experience, on a site that is specifically for asking questions and trading ideas. Furthermore, some individuals have a hard time stating their questions in a clear manner. Does this mean that person doesn't know what they're doing, or shouldn't be doing the job? No - sometimes it simply means they need to clarify the question. For those of you who jumped to conclusions about what I was doing, I'd suggest asking questions next time. If I wasn't clear in my original post, I could have told you that I had no intentions of nailing to concrete, or screwing up any door openings.

Thanks guys. Lets all try to remain civil on these boards.

neolitic

OP was a tad vague, no mention of sleepers.
Rooms generally have doors, and raising the floor has consequences for them.
Vague questions around here frequently come from "posing" HO's.
I have had good results putting down a 6 mil barrier, and floating sleepers over that(i.e. no penetrations) with rigid foam between the sleepers, and sub-floor over sleepers.
If I ask for help, I generally try not to get snippy if I didn't ask the right question.

__________________
Put your location in your profile!
(Sorry....it seems there really are dumb questions)

MacRoadie

The reason I mentioned doors was because doors and adjacent floor elevations (a room adjacent to this one that will not receive hardwood for example) may be negatively impacted by a significant change in floor elevation. Hollow-core doors for example can't be significantly under cut. Solid core doors that can be undercut still need frames and jambs modified.

I realize you didn't ask about doors, but the method of leveling and the type of subfloor required to install that hardwood may be limited by other conditions that can impact the feasibility of the job. If those can't be addressed, then the vapor barrier might be a moot point.

I wasn't suggesting that you were unaware of these conditions, just trying to be thorough.

Kevin75

MacRoadie,

Your post was excellent and appreciated. Some of the other posts were a bit juvenile. For everyone's information:

There are two doors. One has about a 6 or 7" step and won't be a problem. The other opening will be impacted by raising the floor; As such I included pricing for a custom height door and modification of the trim, both inside and outside.

Sorry to everyone if I got a bit testy, but I think some of the comments were quite unwarranted. Admittedly I have less experience with putting down a vapor barrier than some of you, which is precisely why I asked the questions. It's also probably the reason my post was a bit unclear. My brother and I own a small renovation business, and have chosen not to specialize much, primarily because we like the variety and the challenge. Since we've only been in business about 2 1/2 years, there are still many things that we have to learn. When we are unsure of whether we can do a job properly, we sub things out. Otherwise, we make a conscientious effort to learn as much as possible before starting a job.

Thanks everyone for the tips.

Kevin

Teetorbilt

Kevin, remember that the barrier needs to be between the subfloor and the floor or directly under the subfloor. I'd have to see this job before making more comments.

__________________
You can't solve you're problems with the same level of thinking that created the problems.

Albert Einstein

Kevin75

The way I understand it, is that I put the barrier directly over the concrete, then build a sleeper system over that....then nail the wood flooring to the sleeper system. Yes?