Why Does Your Floor Sweat and How to Stop It

Why Does Your Floor Sweat and How to Stop It

Having a sweating floor does not only weaken the foundation of the premises but also creates a slippery surface which is a risk factor within your living space. This comprehensive guide will answer any queries concerning your sweating floor and provide the best strategies to stop the dumbness.

Why Floors Sweat

For most floors, condensation is the main reason for the sweating, especially in warm weather. When warm humid air from outside comes into contact with the cold concrete the air rapidly cools and condenses on the surface causing the wetness.

If nothing is done about the condensation, the concrete slab becomes darker and results in efflorescence in the long run. This is a situation where the floor develops white patches caused when water that had previously been absorbed into the concrete floor slab comes to the surface and evaporates leaving behind mineral deposits carried from the concrete.

Other causes for sweating floors is lack of moisture barriers beneath the slab hence the movement of moisture from underneath to the surface. Do not be fooled by the density of concrete, within it are small capillaries that act as an absorbent hence dampening the affected rooms mostly in the basement.

Easy DIY Tests To Determine Cause Of Sweating Floor

It is easy to determine whether a sweating floor is as a result of humid air from outside or absorption of moisture from underneath with this practical approach. All you need is a 16-inch piece of square shaped plastic and tape.

Tape the plastic on the floor slab when dry ensuring the edges are completely sealed and wait until the floor shows signs of wetness. Remove the taped plastic and assess the nature of wetness. If the concrete patch that was sealed is completely dry and the rest of the floor is wet, it is an indication of a sweating floor caused by humid air outside but if the patch is wet and the rest of the floor dry, it is an indication of a moisture problem.

Functional Remedies To Counter Sweating Floors

Eliminating the factors responsible for sweating is the only effective way to keep your floor dry. Such can be achieved by applying the following techniques:

  1. Sealing all openings to prevent humid air from getting inside
  2. Minimizing humidity of the air
  3. Changing the surface of your floor
  4. Raising the overall room temperature
  5. Improving the circulation of air across the floor


Sealing all openings reduces the draft which results in condensation on the floor. The vents should not be sealed as this would go against construction legal codes. You may also opt for a dehumidifier device to minimize humidity.  Vinyl mats, interlocking floor tiles, and specialized carpets are also effective in keeping floors dry. Another practical option is enhancing aeration for floors with fans because if humid air does not get adequate time to settle condensation will not be achieved. Lastly, heating the affected rooms maintains floor temperature at room temperature hence humid air is not cooled down on the floor surface.

The most recommendable option however is changing flooring material as it is inexpensive and serves you best in the long run.


21 Responses to “Why Does Your Floor Sweat and How to Stop It”

  1. Gunasekaran November 12, 2020 at 4:16 am Permalink

    Crisp & clear article. Thanks

  2. Andrew January 3, 2021 at 1:32 pm Permalink

    Our problem is wetness accumulating under anything we place on the floor. I have a waterproof sealed laminated floating wood floor directly on top of OSB board exposed to the outside. It’s a cabin and about three feet off the ground. So far on the inside I have used vapor barrier tape on OSB seams before installing the wood floor and the floating floor hassome sections of thin layer of acoustic foam that allows air between the floor and osb. Wondering if you think it’s just warm humid air (because we obviously heat the cabin) coming into contact with the cold floor causing condensation? That’s the only thing I can think of. The only no n expert solution I can think of is to make floor warmer somehow with some kind of insulation underneath the osb board and if that would even work? Or would a dehumidifier with a fan be enough to keep condensation from forming underneath items on the floor? Or if you have any other completely different thoughts? Thank you ahead of time!

    • Paul February 2, 2021 at 10:19 am Permalink

      I have a similar problem, in that I have a very cold floor but heat the room. So things that are directly on the floor get condensation underneath them. Have you found a fix yet?

      • Dan Blum February 4, 2021 at 8:42 pm Permalink

        See our response below, but condensation is caused when the dew point falls. The only solution is to remove the humidity with air circulation or dehumidification, or having items on the floor slightly raised with spacers to allow air flow.

  3. Stefan Robert February 24, 2021 at 9:56 am Permalink

    Sometimes we face this problem. Like floor cold but heat the room. The only solution is to remove the humidity with air circulation or dehumidification.

  4. Virginia April 24, 2021 at 12:55 am Permalink

    Our house is 3 years old in the basement under the carpet pad is moist and under my PVC flooring it like its wet, im being told it will dry out in time, i talked to another person whos house is 5 years said they told them the same thing and the glue is still coming up, we pulled a piece of our flooring up and the glue just smears because of it being damp, i do not have a leake and its been cold outside.

    • Dan Blum May 1, 2021 at 3:29 pm Permalink

      You most likely have a moisture issue coming up from the slab as when the house was built they did not put down a vapor barrier plastic layer before pouring the concrete. You could end up getting mold if you leave it this way and mold is a serious health hazard. Your PVC flooring is not permeable and hence is trapping the moisture and dissolving the glue.

      The floor should be fully removed, and the glue diamond grinded off to expose the bare concrete. Let it dry fully. A dehumidifier should also be used to remove moisture in the future. Then we would recommend putting down a breathable surface like carpet tiles so any moisture coming up will just pass through and can’t collect. We offer our ArmorCarpet Squares which are carpet squares attached to a floating support tray which interlocks, but this may be overkill for an indoor application.

      • Yuleisy July 15, 2021 at 4:22 am Permalink

        But what if we don’t like carpets? Is there any other solution?

        • Alex - ArmorPoxy September 8, 2021 at 12:04 am Permalink

          Carpet Tiles are your best option unless you want to use lay down a moisture vapor barrier with an epoxy coating.


          The Armorpoxy Team

  5. Hailey Miller May 20, 2021 at 10:34 pm Permalink

    I found it interesting when you said that condensation causes the floors to sweat. Like you said, when warm air comes in contact with cold concrete, the air cools and condenses which causes wetness. Our garage floor is so slippery since Monday, and my children almost slip while running. I think I should look for floor specialists who can repair our floor to avoid accidents.

    • Dan Blum June 22, 2021 at 2:30 pm Permalink

      Hi Hailey,

      We would recommend adding an additional topcoat to your floor. You can best achieve this by re-prepping the floor and then using a topcoat with non skid additive. Feel free to reach out to us directly and we can help point you in the right direction.

  6. Ron Adhikari May 27, 2021 at 6:27 am Permalink

    I recently converted my 1971 built house’s one car garage into office space. Contractor built a floating plywood subfloor with decking system and insulated the space between concrete and plywood with R-39 bats. There is no moisture barrier on concrete surface, the bats sit there with paper on top. We opened a plywood after 2 months to check (part of inspection) and found moisture trapped at the bottom of fiberglass and concrete, mostly on the central area of batts. Do I need to worry about it? I will have padding and carpet on the top of OSB floor but my worry is- this moisture may destroy all the insulation and then eventually all the woods. Does it help to reduce the moisture underneath if I run a dehumidifier in that room? I have about 10-12 inches of space where insulation sits and wondering if I need to run a dehumidifier in that space. Any suggestions would be helpful. Thanks!

  7. Mark July 5, 2021 at 3:22 pm Permalink

    My home is 22 years old and for the first time I have a wet circle 36 inches across. it is only wet around the outside of the circle. My fundation in concrete and flooring is carpet. Is this caused by my floor sweating

  8. Manny July 12, 2021 at 12:15 am Permalink

    We recently replaced our tiled floor with engineered Brazilian Cherry wood. We have now noticed (two separate incidents) very small water puddles that were cleaned (dried) immediately and have caused zero damage to the wood floor. We live in South Florida so humidity is an issue. The concrete slab was sealed prior to laying the floor in order to prevent moisture problems. And so far my only recourse has been to lower the temperature on the central AC. What do you think?

    • Alex - ArmorPoxy September 8, 2021 at 12:01 am Permalink

      Hi Manny,

      Your line of thinking is correct. Lowering the temperature as well as making sure to seal up any openings can help with moisture issues in the floor.


      The Armorpoxy Team

  9. Shane July 19, 2021 at 12:27 pm Permalink

    I have an area warehouse slab that has water trapped underneath and that portion of the slab sweats profusely. I am looking for a plan of attack with suck a big open area to stop the sweating and the floor is very slippery. Any suggestions?

  10. Vicki August 1, 2021 at 2:21 pm Permalink

    I have issue with concrete floor sweating under area rug. We built a glass sun room on top of former patio. We have portable air conditioner in this room. It has been hot and humid and floor is wet and sour smelling. What can he dine to stop this?

  11. Kathleen August 9, 2021 at 4:49 pm Permalink

    Thank you for this informative article. My house is 45 years old in a hot, tropical climate, but have never had problems with moisture. About 8 years ago I painted my house and installed vinyl flooring over wood laminate in the bedrooms (I know, I know, a big no no and have since learned my installer was incompetent.) About 2 months later, my bedroom walls began showing signs of moisture around the baseboards, rising to 24 inches, hence diagnosed with capillary ascension. However, it has just come to my attention that perhaps it was the new “unbreathable” vinyl flooring that caused the moisture that sought escape through my walls. I ask this because I have been believing that the moisture issue will eventually move to the rest of the house and it would be a relief to know that it was only the flooring. (Nevertheless, I am going to moisture proof the entire house.)

    • Alex - ArmorPoxy September 7, 2021 at 11:50 pm Permalink

      You are very welcome Kathleen!

  12. Beverly September 17, 2021 at 9:23 pm Permalink

    Ceramic tile is moist and slippery in screened porch. How to keep dry?

  13. Marshall September 19, 2021 at 2:05 am Permalink

    Anyone have a solution for a sweaty floor when you’re trying to sweep it with a floor dust mop and it pretty much goes nowhere? I sweep lots of hallways in a school.
    Sweeping compound maybe?

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