Should I seal slab before lay vinyl laminate floor

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I have a 2 story house that is on a slab, garage, laundry room with tile floor, 1/2 bath with concrete floor, and 2 other rooms, den and bedroom, all are on the first floor slab.

I am removing the short nap carpeting and going to lay vinyl laminate plank flooring that has a thin rubber type backing. The flooring store, which also does installations, said this type of flooring does not need the floor to be sealed, nor a vapor barrier, nor any additional underlayment. However I would feel more comfortable sealing the floor. Should I not be concerned? We don't have a water table issue. Should the floor be sealed to prevent any moisture coming up? With what?
 
I would. I did. Listen to your guts. I used polyurethane 25 years ago. Got it in 5 gallon buckets. Used paint rollers to apply.
 
If it already has the vapor barrier built in, you don't need it. What does the manufacturer say?
 
Polyurethane won’t create a moisture barrier, if you need one.

Reference the instructions that come with your product. They’ll likely tell you to make sure the concrete is properly cured and dry. If you need a moisture barrier, plastic that’s at least 6 mils thick or a product like Pergo Gold 3mm underlayment will do the job. Be sure to tape the seams.

Here are the instructions from the Lowe’s Smartcore product that I used:
 
The living area of the slab , should have a vapor barrier under the concrete. The garage is any ones guess. I would take a 12x 12 or better a 2ft x 2ft piece of clear plastic sheeting and tape it to the garage floor. wait a few days or a week and see if there is any moisture under the plastic.
 
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It seems that if there IS a moisture problem, laying down a vapor barrier might still be a problem? What happens to moisture that condenses under the barrier and sits there for years? Mold? Algae?

Would installing over an engineered subfloor system be a better solution? DriCore and Barricade are a few examples. I don't know. I'm asking.
 
Originally Posted By: doitmyself
It seems that if there IS a moisture problem, laying down a vapor barrier might still be a problem? What happens to moisture that condenses under the barrier and sits there for years? Mold? Algae?

Would installing over an engineered subfloor system be a better solution? DriCore and Barricade are a few examples. I don't know. I'm asking.


It sounds like you should consult an actual professional not sales staff at the flooring store. Many places are unfamiliar with the products they sell.

It really depends on how much you want to spend, I always see those tiles at the store but I have never seen them or even heard of them being installed and I renovate houses in Toronto professionally.

EDIT: Just paint it and rock on, that vinyl plank has good water resistance. It is also cheap enough that if it does get trashed it is whatever. That stuff feels cheap and we only use it for basements because for the reasons mentioned above.
 
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I bought my house about 3 years ago and did a flip but moved in instead of reselling. Pulled up the laminate that was existing (house is on a slab) and there was a lot of moisture between the vapor barrier and slab. Replaced it with new laminate and a plastic vapor barrier. I think the cold slab against the warm flooring causes a natural amount of moisture to condensate - even in Phoenix.

I remember when shopping there were a lot of different options, and some included a pre-installed sound/vapor barrier.
 
I am in the process of re-flooring my entire house. I definitely like tile better but not the price.
You don't need to seal the concrete. Don't skimp on the underlayment though. I had laminate with backing and they talked me into underlayment anyway. I hate that room it feels bouncy. I used three types of underlayment. I like the one that is thin black like scuba fabric it works Great but you really don't need anything.
Look at this way if the concrete sweated your carpet would get wet. It's fine.
 
Originally Posted By: Panzerman

Look at this way if the concrete sweated your carpet would get wet. It's fine.


Carpet breathes, laminate doesn't.
 
Originally Posted By: Panzerman
I am in the process of re-flooring my entire house. I definitely like tile better but not the price.
You don't need to seal the concrete. Don't skimp on the underlayment though. I had laminate with backing and they talked me into underlayment anyway. I hate that room it feels bouncy. I used three types of underlayment. I like the one that is thin black like scuba fabric it works Great but you really don't need anything.
Look at this way if the concrete sweated your carpet would get wet. It's fine.


I noticed the bouncy feeling as well but it goes away after a while in high traffic areas and makes the floor feel more like a real wood floor instead of laminate on concrete
 
At my workplace I have required professionals come back and redo sup par work on more than a few occasions. Bad concrete. Wall in a wrong location. Illegal wiring. You name it.

It's my responsibility and ultimately rests on me. If you had added the word competent in front of professional, it would have been much more palatable. I haven't dealt with moisture underneath a vinyl floor plank and was simply asking.

So, how do you handle moisture underneath basement vinyl plank flooring?
 
Originally Posted By: doitmyself
At my workplace I have required professionals come back and redo sup par work on more than a few occasions. Bad concrete. Wall in a wrong location. Illegal wiring. You name it.

It's my responsibility and ultimately rests on me. If you had added the word competent in front of professional, it would have been much more palatable. I haven't dealt with moisture underneath a vinyl floor plank and was simply asking.

So, how do you handle moisture underneath basement vinyl plank flooring?


I was under the impression that this was just the ground floor of a house on a slab. If I were concerned about moisture build up under my basement flooring I would repair my leaky basement before putting a floor down.
 
Originally Posted By: dishdude
Originally Posted By: Panzerman

Look at this way if the concrete sweated your carpet would get wet. It's fine.


Carpet breathes, laminate doesn't.


It also wicks up and absorbs moisture while it is breathing. It could also allow mold to grow on the padding or carpet backing. I've seen it in several clients homes over the years.

OP I would consult the manufacturer of the laminate floor product you plan on installing.
 
Originally Posted By: doitmyself
At my workplace I have required professionals come back and redo sup par work on more than a few occasions. Bad concrete. Wall in a wrong location. Illegal wiring. You name it.

It's my responsibility and ultimately rests on me. If you had added the word competent in front of professional, it would have been much more palatable. I haven't dealt with moisture underneath a vinyl floor plank and was simply asking.

So, how do you handle moisture underneath basement vinyl plank flooring?


Super simple test reveals an issue. Take duct tape and secure a 4X4 piece of visqueen on the floor carefully sealing the edges. Wait 24 hours. If moisture is present in any significant amount you need to seal it first. Floor sealer is relatively cheap.

Even ceramic tile can be affected by excessive moisture when the grout is sealed improperly or the tiles are very large with a super tight grout line.
 
Yes, I'm aware of MVER testing, plastic sheet test, and RH testing (ASTM F2170 - 17) of concrete slabs. The first two have limitations and can be misleading. I suggested the concept of a breathing sub floor and wondered if it has merit, admitting that I have no experience with it. While an on-grade slab should be less vulnerable than below grade basement slab, I have dealt with poor professional grading work on completed buildings that directs water towards the building where it can get under the on-grade slab. My mistake for bringing up below grade when the OP stated on-grade.

As I asked earlier, the suggested plastic sheeting over a problematic slab seems like a recipe for disaster. The water will still condense under the plastic and then what?

What are the floor sealer options other than expensive epoxy?
 
Originally Posted By: doitmyself
As I asked earlier, the suggested plastic sheeting over a problematic slab seems like a recipe for disaster. The water will still condense under the plastic and then what?

What are the floor sealer options other than expensive epoxy?


Perhaps you misunderstood me. The procedure is for TESTING only not a solution.

We have used liquid floor sealers that I believe are polyurethane based. They work well
 
Thanks SteveSRT8. No misunderstanding, but maybe I could have worded my response better. You brought up both ideas of testing and using a floor sealer, which sounds like the proper solution to mitigate a moisture problem.

I'm still scratching my head about previous suggestions to use a plastic sheet vapor barrier. Unlike a wood framed floor where moisture can move back and forth, once moisture condenses underneath plastic, vinyl floor, etc. its stuck there.

I'm also curious about the DriCore type products and wonder if they are a legitimate solution. One poster above implies not.
 
Originally Posted By: doitmyself
Thanks SteveSRT8. No misunderstanding, but maybe I could have worded my response better. You brought up both ideas of testing and using a floor sealer, which sounds like the proper solution to mitigate a moisture problem.

I'm still scratching my head about previous suggestions to use a plastic sheet vapor barrier. Unlike a wood framed floor where moisture can move back and forth, once moisture condenses underneath plastic, vinyl floor, etc. its stuck there.

I'm also curious about the DriCore type products and wonder if they are a legitimate solution. One poster above implies not.


The manufacturers of the flooring are the ones recommending the plastic barrier.

Quote:
Can I install Pergo over concrete?
Absolutely, but with certain precautions. The concrete must be fully set. That means it is also below 4.5% moisture reading using an approved moisture meter or a calcium chloride test (available at homecenters) with a reading of no more than 5lbs/1000 sq ft/24 hours. Should moisture record above these levels, Pergo is not recommended. In all cases, a 6 mil polyethelyne moisture barrier overlapped at least 12" and taped is required on all concrete installations.
 
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