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. Contact ArmorPoxy if you have additional questions.


43 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.

      • Bobby Kaczor March 21, 2022 at 4:23 pm Permalink

        can you be more specific on the moisture vapor barrier, how is applied, please?

        • Kevin August 14, 2022 at 1:51 pm Permalink

          Hi Bobby,

          The moisture Vapor Barrier product is rolled onto the substrate like many of our other products and has a 2 to 1 mix ratio. We suggest running a moisture test prior to any epoxy application where there is a possibility of potential moisture issues. Please buy a calcium chloride test. If the readings show a number greater than 3.5-4 than this means you have significant moistures issues. You will have to use a special moisture barrier epoxy like our ARM409X and MUST shot blast for adhesion on concrete.

          Thank you,

          The Armorpoxy Team

  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?

  14. Brantley November 15, 2021 at 9:29 pm Permalink

    I have a tile kitchen floor with concrete between the tiles. Noticing the concrete at 2-3 places has started to sweat and the problem is exasperated when applying pressure to the tiles. We’ve been in her house about a year and a half and did not notice the issue last winter. Think I have condensation problem or some sort of moisture issue underneath?

    • Dan November 16, 2021 at 3:48 pm Permalink

      Hi Brantley,

      It sounds like there is a moisture issue in the slab. Are you planning to redo your floor or just looking for a solution to fix the sweating issue?


      The ArmorPoxy Team

  15. Braden Bills December 28, 2021 at 4:14 pm Permalink

    I’ve noticed condensation on my floor, and I’m not sure what to do about it. It makes sense that I would want to get a professional to take a look at it for me! I can see how this could be a cause for some more serious issues in the long run.

    • Alex January 3, 2022 at 5:16 pm Permalink

      Hi Braden,

      Glad you found he blog post informative. Let us know if we can assist in providing any more info on our product range.


  16. Marcia Bassett December 29, 2021 at 8:42 pm Permalink

    We have never had water in our basement until we put a vinyl floor down. The vinyl floor is void if we put a vapor barrier below the vinyl flooring. What causes this and how do we stop this – I am so discouraged about this will we have to replace the floor? Any help or answers woule be greatly appreciated.

    • Alex January 3, 2022 at 5:27 pm Permalink

      Hi Marcia,

      Hi, moisture can come from either up through the slab, or by condensing on the cool floor (like water droplets forming on a glass of water). You probably had this issue all along, but since the floor was uncovered, any moisture just evaporated away.Now that the floor is covered with a non-permeable covering, the moisture has no way to evaporate and hence is building up under the fooring.

      First, you need to pull up some of the floor and do a moisture test with our Moisture Test Kit and determine if there is excessive moisture coming up from the slab (over 3 lbs/1000 sq ft/24 hours). If there is then the flooring needs to be fully removed, the floor prepped by grinding or shot blasting and then a Moisture Barrier Epoxy installed with we offer. This barrier holds back the moisture from coming through the floor, but the floor needs to be tested first to determine the issue.

      The second reason why this could be happening is that the floor is very cool and forming condensation. The way to get rid of his is by removing the moisture from the room with dehumidifers or proper hvac and ventilation since the building of moisture in the air can condense on a cool floor so better ventilation or removal of the moisture is needed.


      The ArmorPoxy Team

  17. Hilary Morris March 11, 2022 at 9:45 am Permalink

    Hi we have a holiday chalet with ceramic tiles throughout. After having the cental heating switched on the floor becomes wet. I have purchased a demidifier and would like to know what is the best flooring to help solve this problem.

    • Kevin March 17, 2022 at 2:55 pm Permalink

      Hi Hilary this doesn’t sound like a flooring issue, it’s most likely a humidity issue in the house.

      The Armorpoxy Team

  18. Fabiola Laureano March 22, 2022 at 2:13 pm Permalink

    Hello Donato! I have a question, I have a large outdoor area covered with sandblasted granite flooring, the floor was waterproofed with water-repellent, after waterproofing the floor had darker stains in some places, before it did not have these moisture stains. The supplier explained to me that when applying the anti-fungal agent, some points of moisture below may have surfaced… I still don’t understand because before the anti-fungal agent there were no such spots. Well, what could I do to eliminate those damp stains that seem to come from under the floor and after the water repellent don’t dry?

    • Kevin August 14, 2022 at 1:44 pm Permalink

      Hi Fabiola,

      Please send us an email to infor@armoroxy.com so we can take a look at the area of concern and give you our best recommendation.

      Than you,

      The Armorpoxy Team

  19. jenny April 29, 2022 at 8:50 am Permalink

    Hi there, this was really helpful!
    Similar to another post, we recently redid the kitchen and instead of pulling up the old tiles which are over the concrete slabs, we put interlocking vinyl matte tiles over them. We have been struggling to find the reason why the wall surrounding the kitchen is damp from the bottom and I now suspect this is because the original tiles are sweating, that condensation is trapped and the only way the built up droplets can get out is where the tiles finish (i.e. the walls).

    We don’t want to spend loads more on this and are actually planning to sell soon but will be replastering the walls and need to ensure they don’t get wet again. As a fairly cheap and quick option, we are thinking of sealing off the edges of the tiles (we just need to get under the cabinets to do this) so the moisture can’t get to them. And perhaps laying down an absorbant breathable material under the moisture causing appliances e.g. dishwasher and washing machine so the moisture path is more controlled… am worried that if we just seal off the tiles, the moisture will still find its way to under our walls and ruin the new plaster again.

    Does this sound like a decent plan and if so, are there any materials you recommend?

    • Kevin August 14, 2022 at 1:39 pm Permalink

      HI Jenny,

      I would recommend putting an elastic type product like our Armor Liauid Membrane down. ensure that that all substrates are dry and water is not present otherwise the coating will not adhere. Apply thin layers of the Liquid Membrane and this should help to reduce the floor sweating.

      Thank you,

      The Armorpoxy Team

  20. Tracey Prunty June 6, 2022 at 3:38 pm Permalink

    We just moved into our new home. We didn’t stain our concrete in the house, but we did have it grinded and polished. There are some spots in a couple of places that look wet sometimes, but when I touch them they seem dry. Should I be worried

    • Kevin June 7, 2022 at 9:16 pm Permalink

      Hi Tracey,

      I wouldn’t be too concerned but you can run a moisture test to see if there is moisture coming through. What type of room is this?

      The Armorpoxy Team

  21. Francisco June 27, 2022 at 2:31 pm Permalink

    My issue is that on the upper floor there is an air conditioned server room and the room below does not have any air conditioning and the floor sweats. the floor in between the two is a 5″ reinforced concrete slab. Below is warmer than above… I plan to place batt insulation in the ceiling and placing a sheetrock ceiling to support the insulation, in order to prevent the humid air from reaching the cold ceiling/ support the insulation and provide an aesthetic look.

  22. Brett Middleton July 6, 2022 at 12:56 pm Permalink

    I live in an apartment, my floor boards in the hallway are seeping water through the cracks when I walk over them. My complex has left a fan and a dehumidifier on since yesterday around 2pm but when I checked this morning my floors still are seeping water when I walked over them. I left the dehumidifier and fan on while I went to work. Will this get solved by just letting them run till this afternoon? Or will I need to ask my apartments office if they will replace those floorboards to get rid of that moisture that is underneath it?

    • Kevin August 14, 2022 at 1:37 pm Permalink

      Hi Brett,

      It sounds like those boards will most likely need to be replaced if water is persistent.

      The Armorpoxy Team

  23. Anthony Wool January 26, 2023 at 12:58 pm Permalink

    We have a problem in the two bedrooms of our bungalow, we have bitumen floors and in the both outside corners we re getting moisture on the floors in the corners .We have no damp issues on the walls, do you have any suggestions.

  24. Mortgage Broker Australia March 13, 2023 at 1:58 am Permalink

    Thank you for this blog about Why Does Your Floor Sweat and How to Stop It. I found it amazing.

  25. Sonya Caudle June 21, 2023 at 9:11 pm Permalink

    We have lived in Ft. Worth, Texas only a couple years. This summer we have noticed what looks like water at the edge of the front covered porch concrete against the brick on exterior of the home It is not a lot but enough to be concerning for us. The weather over the past week has been over 100 with high humidity and our A/C inside is kept at 68 to 70 inside. There are no water pipes on this side of the home to our knowledge. Is this what you are referring to as condensation or the concrete sweating? Will this interfere with the integrity of the home over time? What is the best way to correct this?

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