Rubber & Vinyl Floor Moisture Testing

The Different Characteristics of Rubber and Vinyl Flooring


Vinyl and rubber floor products have a myriad of advantages including excellent water resistance, easy maintenance, and a natural scratch resistance. They are typically durable and long lasting and come in a variety of applications to suit almost any location.

The other advantage to vinyl floor products is that they are available in a wide range of looks and styles to compliment any décor. Vinyl flooring has increased well beyond the standard sheeting in the range of floor products available. Vinyl tile, in both commercial and standard grades, and vinyl planking are options with either locking or standard glue-down installation. Some vinyl floor products include limestone or fiber additives or backings that increase their durability and chip resistance or offer more cushioning underfoot.

A good example is flex flooring, a product made to go over existing vinyl flooring. The combination of polyurethane top layer and fiber backing give it better flexibility for both installations and for comfort.

Rubber flooring provides a slip-resistant surface that holds up very well under heavy foot traffic. It can be purchased with a number of designs, colors and patterns for an easily customized look suited to either home or industrial use. Textures like round stud or diamond grip increase the traction level of foot traffic while still having an industrial-standard resistance to wear and damage. Rubber flooring is available in either tiles or sheets and can be applied with glue, for a movement-free flooring, or as “loose lay,” attached with double-sided tape for quick removal if required. Rubber tiles are also available in interlocking styles for adhesive-free applications over a variety of surfaces.

Because both vinyl and rubber floorings are naturally impervious to water, it would seem that moisture testing for rubber or vinyl flooring applications might be unnecessary. But the cost of moisture-related problems can be just as high even with these seemingly “moisture proof” floors.

How Can Moisture Cause Problems with Rubber and/or Vinyl Flooring?

The real problem for vinyl and rubber flooring is often in the subfloor, or in giving moisture access to the subfloor. Moisture can impact the flooring in two locations:

  1. Seams (if there are any) – Tiles and planking in either vinyl or rubber styles will naturally contain more seams in a finished floor. In a loose-lay or floating installation, those seams provide spaces for moisture to seep down through the seams and either enter the subfloor or sit between the subfloor and the flooring affecting both the product, the subfloor and the adhesive used to connect the two. In a fiber-backed product, it is easy to see how this can also cause warping, buckling, swelling or even lead to mildew.
  2. The subfloor itself – Because rubber and vinyl products are so well suited to damp or humid conditions, they are often applied directly (or indirectly) over concrete or other sub floors. But if that subfloor is not dry to acceptable levels, the reality is that product and/or adhesive is at risk of a flooring failure.

Moisture Prior to Installing Rubber and/or Vinyl Flooring

Moisture, particularly in a concrete slab, can come from a number of sources. If the slab does not have an adequate moisture barrier underneath, moisture can wick up from ground sources in a continuous cycle. And any existing slab can still be subject to moisture intrusion if it is in contact with leaking plumbing or irrigation systems, ground moisture or excess humidity in the environment. In a new slab, if the concrete has not dried internally to the levels acceptable for the particular flooring and/or adhesive used, moisture will continue to work its way to the surface under the applied flooring. (Explanation of the process of moisture movement in a drying concrete slab)

For any flooring installation, adequate moisture testing is imperative. For a concrete subfloor, relative humidity (RH) testing is the best way to get a true picture of the moisture conditions within the slab to prevent any negative moisture impact to the finished floor. The ASTM F2170 recommends in situ probes for RH testing. Test methods like the Rapid RH® L6 provide fast and accurate test results within the subfloor so that any issues can be remediated before putting the flooring at risk.

When installing a rubber or vinyl floor, moisture testing is just as, or even more, important than it is with any other flooring product. Because where the rubber meets the road, moisture can still jeopardize your installation.


  1. Claire says:

    Hi. We had a new concrete slab laid over a damp-proof membrane a month ago, with piped underfloor heating laid within the slab. The underfloor heating has been on for two weeks now. The new slab is 4-6 inches thick. It is adjoining a much older slab (which also has a DPM) in the adjoining room (which we have just knocked through).

    The flooring company came today to lay Quickstep Pulse click vinyl wood-effect (plank shape) flooring with basic underlay. They did a surface moisture test and said the moisture was far too high at around 5-6% when instructions say it should be < 1.5%. They didn't lay the floor and said it might take 6 months to dry. The moisture levels seemed to be high across both slabs, even the old one (we don't know how old – possibly 30 years?).

    What happens if we lay this floating vinyl floor, with underlay, on a damp surface? How would it damage the floor? What are our options if it is still just as damp several months down the line? Would you recommend painting on a sealant?

    Thank you!

  2. Lilian M Rogers says:

    Jason’s article caught my attention and I wonder if I can get some advice about my situation. The concrete slab foundation of my 1950’s ranch house had glued down vinyl composite tile flooring. In August 2018, I bought luxury vinyl plank flooring from One of the big box stores who subcontracted to install it. A man came out to measure and take moisture readings. He said the moisture was high but if I bought 6 mil plastic and taped its seams it would do fine. So I did that. When I got home from work after the contractor left on the first day, at the edge where I could peek, I noticed no plastic had been put under for as far as I could see for about one third of the total flooring job. I called the big box store to complain. They spoke with the contractor and he insisted he had put down plastic. I went home midday the next day and the guy was putting down plastic but did not appear to be taping it, just unrolling big irregular pieces cut all jagged and overlapping them like a badly made jigsaw puzzle. I had to get back to work so I didn’t see if he actually taped it after. I called the store again to complain and they spoke with him and they said he claimed to have taped it. The store assured me there’s a one year warranty on workmanship so if I encounter any problems to let them know. Four months later I’m getting whiffs of mildewed vinyl smell. I’m thinking if I could measure the humidity of the flooring to see if it exceeds the manufacturer’s recommendations (Less than 5 percent), then I’d have a case with the big box store. Yesterday, a concrete guy measured areas in the house floor that are bare concrete and the highest humidity reading was .67 of one percent. So the slab itself appears dry, at least in the areas not covered by the vinyl. Do you think it’s worth my time and effort to do what I probably should have done at the onset- tear up some floor in the one room the worker insisted he did to find out did he actually put plastic? How important is it for the plastic to be taped? What kind of meter can I use to get the moisture reading for under the vinyl plank flooring? My concrete guy said his meter only reads concrete and wood. If I can’t afford to buy the appropriate meter, who would have one ( a flooring company?) can I ask the big box store to send out the first guy if I don’t know for certain that I have a problem? Thanks!

    • Jason Spangler says:


      Thanks for the questions. You ask many, on various subjects, so I hope to answer as many as possible. First, you don’t mention any real cosmetic or performance issues with the floor at this point. Many of these questions should be directed back to the manufacturer of the flooring product or big box store. Questions like, is the warrant still intact if the plastic isn’t taped? Does the floor have any antimicrobial backing on it? These may help you to answer the question of whether you should pull part of the floor up to verify any potential mold growth and taping of the seams. As far as the smell, again, I would contact the big box store and the manufacturer and have someone come out and inspect if it is really something that concerns you. You may also be able to have an air quality company come out and take samples. Many times odors on new floors may last for an extended duration and then go away, but there is nothing wrong with voicing your concern. As far as the concrete moisture scales you mention, none of them are concrete RH%. I can only guess that the one you reference from the manufacturer is moisture content, but I can’t be sure. The other scale from your concrete guy is one that I can’t even make a guess on. I hope this all helps. Good luck.


  3. Anna says:

    Cant mold grow under any floating floor with a moist slab? It doesn’t make sense to completely seal a wet slab that wont be able to breathe with a vinyl floor. I don’t care how waterproof this flooring is.

    • Jason Spangler says:


      Thanks for the question. This is one of the questions that people discuss with the increased interest and usage of WPC flooring. In my opinion, with the moist, humid environment created by the WPC, the likelihood of mold increases.


  4. Bree Ward says:

    I agree with you when you said that the advantage of vinyl flooring is that it has a wide variety of styles that can complement any decor. However, it can also be prone to moisture that might occur in the subfloor area. I like how you discuss it’s detailed and how testing is important in the installation. In case I’ll have to change my flooring to vinyl, I’ll definitely look for contractors who install them with moisture resistant techniques.

  5. Martin says:

    I have a vynil installation that after 6 months starts to appear circualar bubbles and looks like an orange skin. What could be the source of this problem?

    • Jason Spangler says:


      Thanks for the question. It could be moisture, it could be adhesive, it could be vinyl, it could be an installation issue, or a combination of any of these three. I realize this is a vague answer, but I don’t have much to go on. Is this a wood or concrete subfloor? Were moisture test done on the substrate? If so, what were the results? How many bubbles have appeared over how many square feet? Have you had anyone else look at it? Sorry I can’t be of any more help.

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