Another...basement floor question!

girlgroupgirlSeptember 9, 2011

We have a 1920's house and probably originally had a dirt floor in the basement. Sometime in the 70's it was dug out and a slab was poured, however it appears no membrane was laid. The floor has never cracked, but it does mitigate moisture at times. Not "wet" (in some places) never wet but just enough to cause failure to water based glues.

We had VTC flooring laid at the suggestion of the contractor, floor professionals and the plumber who all said that there was a need for water remediation. This is just vapor and not "water". We have areas were absolutely no moisture transpires. There is no landscaping anywhere near these areas, it's all near the driveway. No water appears to ever have gotten into the walls or through the walls in this area.

In the back we had tile failure due to two floodings last year during hurricane season. That is very rare for us to experience and have not had flooding again but did have glue failure with the tile.

The tile color we chose became obsolute (Azrock), and the floor specialist we used and another flooring man both suggest relaying a similar floor. I don't think it makes much sense if that particular product uses water soluble glues (plus nothing else "goes" that they have to offer. In a few areas the floor leveler has failed (after 3 years). The contractor who installed it said that sometimes happens. The other fellow we had look at it said it was laid poorly). It causes lumps under the tile where it is lifting away.

I have no idea what should be done. We need a basement floor that is basic and I like a 50's look: simple, easy to care for (which is why I chose VTC). If the concrete could be refinished and sealed that would be fine, but I'm not sure how to proceed.



girlgroupgirl (who usually frequents the gardening forums!)

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There is clearly no polyethylene and/ or xps under the slab to impede the flow of water vapour into the basement. Short of removing and re-pouring the slab with xps/6 mil poly under it, there is no way you can use low-perm floorings directly over the concrete. Any coatings you use will fail as the pressure of water vapour will push it off. Crystalline waterproofing will work but is expensive and should only be applied by professionals.

However, with proper preparation and installation methods, you can still use just about any above-grade flooring in your basement except hardwood.

    Bookmark   September 9, 2011 at 10:36PM
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Worthy, do you mind explaining what you consider "proper preparation" especially for vinyl composite tile in a situation like this? Yes, the installers and general contractor all agreed that any kind of waterproofing was not affordable in our situation (not like we have a fancy house and were going through major & costly renovations at the time).
Basically they laid leveler right over the concrete that they had scraped of other flooring material and prepared for leveler. I do not think that the installers I had did a poor job, I just think the leveler failed in this one small area.
Would another flooring material work better? Or removing flooring and doing something (staining?) the concrete, or perhaps ceramic tiles?
The problem with the VCT the installers both told me is that they are only rated for water soluble glues. My FIL suggested bypassing the warranty and using a waterproof glue but I am not schooled enough to know what is the better move (or more sensible in this situation move?). The warranty is already pretty much not an issue with the lack of vapor barrier, I guess.
We can't put in a sub floor of any kind, not enough head room. They've already had special permission to get extra head room because of my height.

Thanks for your help,

    Bookmark   September 10, 2011 at 8:40PM
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We had VTC flooring laid at the suggestion of the contractor, floor professionals and the plumber who all said that there was a need for water remediation.

This makes no sense. Vinyl flooring can't remediate liquid water problems.

To repeat what you correctly diagnosed to begin with: Your basement slab likely has no insulation nor polyethylene below it. So water vapour is coming up through the slab in sufficient quantity and pressure to affect the impermeable glues and vinyl.

As this Building America guide from the US Energy Departmentnotes( (p.20), in basement slabs, "in general, sheet vinyl flooring should be avoided."

Your floor "specialists" should have taken mid depth instrumented readings of the relative humidity of the slab before laying vinyl. I'm betting they didn't.

You can still successfully lay vinyl tiles on the floor with minimal loss of headroom by first applying a Delta-FL membrane or equivalent followed by 5/8" plywood or OSB, vinyl underlayment and then the vinyl flooring. The membranes also work with carpet and laminate. For tile, I would use a crack isolation membrane such as Ditra.

It's unfortunate that the old methods persist through a combination of ignorance and false economy or worse. (Like the renovation seminar leader who advocated basement floors on sleepers to disguise water leakage. At least till the money changed hands.)

    Bookmark   September 10, 2011 at 11:04PM
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Thanks Worthy.
I did not find the membranes when we had this flooring laid. I agree they should have known (we did tell them!) that there was no vapor barrier. I love the idea of the membrane. No plywood was ever laid, that is for sure and no vapor measurements ever taken. Sadly, the guys who laid the floor have the best reputation for flooring in the city. The 2nd company I had come out has a poor reputation (but a friend in the carpet industry suggested I try them anyway). Not quite sure now who I turn to, but at least you have given me something to go on.
I do not have sheet vinyl, but the 12" vinyl squares. It pains me to have to replace them and we can't get the colors we originally chose anymore :(
Thanks so much for your help.
P.S. I meant to say that the contractors felt there was NO need for water remediation, it is only vapor that comes up. Well, we did get water in the house but that was in a flood situation and unusual....but it still ruined the floor there. Next time we know to buy some extra boxes of tile....

    Bookmark   September 11, 2011 at 8:07PM
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it is only vapor that comes up

And unable to move into the open air of the basement, it remains trapped under the vinyl (tiles or sheet) condenses into water and lifts the flooring.

Older vinyl asbestos tiles were vapour permeable and did work in basements.

    Bookmark   September 11, 2011 at 8:57PM
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The cheapest solution will be one with the hardest DIY labor component. Jackhammer the floor, put down the proper vapor barrier, and then pour with tinted concrete. Any other type of topically applied membrane will likely be more expensive than plain concrete. The concrete can stay without a sealer on top for light wear until you can afford to have it epoxy clear coatedl

    Bookmark   September 11, 2011 at 11:55PM
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Aha! Worthy, I think you nailed it. I do not think these installers realize that this flooring is NOT vapor permeable.
Live Wire Oak, I am just not going to be jack hammering up any floor or laying any new concrete. That is well beyond my ability. I'm a DIY gardener and can not manage anything beyond the simplest of home repairs myself.

    Bookmark   September 12, 2011 at 12:02PM
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So, I mentioned these products to a few of my friends and they asked the question I've been wondering too...where does the moisture go? Where does it go if you trap it under plastic? How does it vent and not cause mold if you use a membrane?

    Bookmark   September 16, 2011 at 12:06AM
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When concrete is properly poured with a vapor barrier, the moisture stays in the soil and does not soak into the concrete. Your basement stays drier (how dry will depend on how the walls were waterproofed) and you can install a non porous floor like vinyl or carpet with padding with no issues.

When you place a topical membrane on top of the already poured concrete that is without a moisture barrier, the moisture is still present in the concrete and exerts pressure on that moisture barrier (such as the glue for a VCT floor) and eventually that coating peels off. The water sits in the concrete and can be a nasty smelly mess. It's one of the reasons basements smell musty. Topically applied waterproofers do not really waterproof. They just provide the area of most resistance.

If you don't put down a moisture barrier, and then you lay a moisture barrier type flooring like sheet vinyl or carpet padding with carpet, the moisture comes through the concrete and makes nasty mold and mildew under the flooring. If you lay something like ceramic tile that can let the water vapor pass through the grout lines, then some of the water will evaporate into your basement air and some will stay in the flooring itself. Tile would be your best bet for flooring if you don't want to redo the concrete.

So, you either accept the mold and mildew that go along with putting in flooring, or you accept that you cannot put living space style flooring in your basement, or you redo it so that it can become an acceptable living space. Redoing it would cost quite a bit to have a pro do, but there is a chance for significant savings if you DIY the nasty bits and just hire a crew to float out the concrete.

    Bookmark   September 16, 2011 at 1:44AM
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I mentioned these products to a few of my friends and they asked the question I've been wondering too...where does the moisture go?

I assume you're asking about products above the slab.

The Delta FL reduces the vapour flow by equalizing pressure above and below the slab. But the moisture that does come through exits around the perimeter of the product. You must leave the specified spacing in the manufacturer's specs. Dri-Core works the same way. XPS (extruded polystyrene) is vapour permeable.

In a tile installation, as noted by the previous poster, water vapour moves through the grout lines. I suggested an underlayment of Ditra to reduce cracking; however it also equalizes pressure and directs water vapour to the perimeter of the installation.

    Bookmark   September 16, 2011 at 7:51AM
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i had no idea that there were houses built in 20s without basement floors.

    Bookmark   September 16, 2011 at 8:47AM
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There's always a floor. Even if it'smud

    Bookmark   September 16, 2011 at 10:43AM
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So, how does one know if their concrete has a vapor barrier?

    Bookmark   September 17, 2011 at 1:48PM
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You can't, short of removing the concrete--which kind of defeats the purpose.

    Bookmark   September 17, 2011 at 3:00PM
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No, you can't know if you have a vapor barrier, but you can experiment to see how much moisture is being transmitted through your flooring. Tape down a 2x2 piece of heavy 6 mil poly sheeting with a good quality real duct tape or metal tape and observe the condensation that occurs. A barely perceptible color change in the concrete no color change at all in 48 hours could mean that you have either a vapor barrier, or good drainage under your slab that is moving away moisture in the soil. It also could just mean that your area of the country is in a drought and your soil is just very very dry for an extreme depth.

The most likely scenario in an older home is that you will have some condensation under the plastic. Interpreting how much is "a lot" is a bit tricky. Pretty much anything beyond just the concrete looking dark will mean an actual moisture issue in your basement. That moisture is traveling through your concrete and into your basement air. If you have quite a bit of actual water droplets on the plastic, then this is something that needs more attention now rather than later. You will not be able to install any type of flooring in this situation and need to remediate the causes of the moisture infiltration. The most typical culprits of high moisture infiltration are poor lot grading and improper routing of gutter downspouts. Although, there have been known cases of an underground spring making it's presence known, you start with the simple stuff and proceed to the more complex in your efforts to solve the problem.

    Bookmark   September 17, 2011 at 6:17PM
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I spoke to the contractor and he said they did indeed lay a membrane but he's going to take a look at it all and try and figure out what is happening. Thank-you Worthy for your information.

My house was built in the 20's and did not have a basement originally, it was all dirt crawl space before someone dug 2/3 of it out. We had the contractor dig out some more when we renovated and that flooring was re-poured and proper vapor barrier installed and that particular flooring area is performing perfectly.
So now it is to determine why the floor is failing so we can direct someone to fix it.
We are pretty sure no vapor barrier was installed in the oldest area of the basement because it was a DIY job done in the 50's. I think they never imagined the basement to be used for anything more than laundry and storage.

    Bookmark   September 17, 2011 at 11:23PM
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