Why Does Concrete Sweat? Reasons Behind Sweating Concrete

why does concrete sweat

Concrete sweating is the name given to the appearance of water drops on the surface of the concrete. To practically all of us, concrete seems like a stable and reliable material. But guess what, Concrete can sweat! 

Concrete sweating is also known as Sweating Slab Syndrome (SSS). When warm air in the atmosphere meets cooler concrete, it leads to condensation (water droplets) forming on the concrete. 

If you have a garage made of a smooth slab of concrete, then a sweating floor not only weakens the foundation of the premises. It also creates a slippery surface. That is a risk factor within your working space. Apart from slip-and-fall injuries, slippery surfaces can cause equipment to slip and slide, which can cause severe damages to employees and staff.

Let’s not forget about your home, which is also in danger if you have a sweating concrete floor or walls.

You are reading this article because you are facing the concrete sweating issue. Here we are to provide you with the reasons for sweating concrete. By taking some simple steps, you can prevent your floors from becoming slippery and unsafe. 

Let’s get to know them.

Why does concrete sweat? Reasons behind sweating concrete

why does concrete sweat
source: https://www.concretefaq.com/

There would also be a variety of co-occurring conditions for concrete dripping to appear. Any other factors may also produce damp spots on a concrete floor. We will talk about them extensively.

Concrete reaching Dew Point

Dew point is an atmospheric event that affects the Evaporation rate. The evaporation rate is the most frequent source of concrete sweating in the atmosphere.

 Concrete sweating can occur in places like Egypt when humid, moist air strikes cold concrete within a house. 

The humidity in the air cools down on the top of the cold cement, making it sticky and slick. As the air diffuses, it focuses on objects at or under the temperature of the dew point. 

We all know that the concrete must be below the dew’s temperature to make concrete sweat.

Not enough air

If you have a large warehouse or garage owner, it is most likely to get sweaty due to excessive heat. Of course, you have arranged fans to increase the evaporation rate and keep moisture low. 

But what if the airflow is not enough? Maybe your Garage or warehouse is getting too much hot, which is causing the floor to sweat. A warehouse could need over 100 ceiling fans if it is large enough.

But based on sweating, you have to arrange your warehouse fans. The number will depend on the amount of space and issue. 

Moisture seeping through the concrete

Although concrete is a solid material, water and moisture can seep through it. Water from the soil can slowly creep through the concrete wall. This incident mainly occurs when you have ground under your concrete floor, and it is wet. 

Concrete material is very likely to seep moisture if the upper side of it is heated. That means if you have wet soil under your floor and the temperature is hot, you may expect a sweaty floor. 

Concrete cancer

Over time, you will find that you are starting to see signs of wear and tear on your garage or other building. This is called concrete cancer, the name for the strengthening of steel. The alkali-silica reaction is also known. 

Concrete cancer is caused when steel reinforcement starts to rust within a concrete slab. When the stain rusts, it spreads, displace the concrete surrounding it, and cracks and thereby speeds up the process. 

Concrete cancer can cause persistent damage to the concrete itself over time. This will lead to expensive fixes.

Changing Season

Seasonal change is also responsible for sweating concrete. In the country that has 2 or 3 months of winter,  when the spring comes, floors start to sweat. 

The ground’s temperature stays too low, and air just above the floor starts to heat up, which causes the foot to sweat during day time. 

How to prevent concrete from sweating

How to prevent concrete from sweating
source: https://www.conslab.co.nz/

As we promised now, we will provide some solutions you can apply to stop your concrete from sweating. We will keep it simple and straight.

  • Strong air movement: As we mentioned earlier if your large wear house does not have a vital airflow source, you have to face the sweaty floor. Arrange large fans that will keep the airflow at a minimal range. So that humidity can not affect the concrete. 
  • Use sealer: To protect the concrete and to keep out humidity, use a penetrating sealer. A concrete densifier is first to be used as a first to adopt a penetration stain repellent.
  • Run a de-humidifier: A de-humidifier may be run to attempt to minimize air moisture. As described above, as humidity from the warm air enters the cold concrete, condensation occurs. A temperature differential mostly causes condensation, but you will not notice much.
  • Turn on the heat: Sometimes cold floors get damp and sweaty due to slight temperature differences. Let’s turn the heat up. It will reduce the humidity, also make the floor hot. It will help help to remove the sweating from the floor. Keep the concrete floor temperature and the air temperature at similar levels.
  • Fix the floor: You could spend some money on modifying the form of the garage surface. If you are serious, you never have to deal with the floor dripping again and don’t want to risk changing the garage conditions to stop it. It’s pricey, certainly, but it might not be a bad thing when this is your home forever, and you expect to spend a long time in your garage.

Some Important FAQs

We have tried to keep the information as simple we could. Yet, it is widespread that you might have questions. Here we have arranged some questions and answers. We hope this will help you to understand the topic better. 

  • How long does concrete sweat?

It takes about a month to complete the process. The water for the concrete mixture would eventually evaporate. Do not use a dehumidifier, as the moisture is absorbed too easily and cracking can increase. Thirty more days after project completion, dehumidifier use can commence.

  • Can I put plastic under concrete?

However, recent research has shown that the old traditional six mil Visqueen layer under the platform is rarely useful because of two significant factors: although it may seem waterproof, this material grade allows a lot of water vapour.

  • What type of gravel goes under concrete?

The good results will be six inches of well-graded gravel or properly compacted broken stone material.

  • How many inches of stone should I use for a concrete slab?

Scrape the plate area to approx—7-inch depth allowing a gravel base of 3 inches and a concrete measurement of 4 inches.


A sweaty, slippery concrete floor can cause many accidents. In this article, we have discussed some widespread reasons behind sweaty concrete. You can get rid of this just by following the steps in the solution part.

We hope this article will help you to fix your concerned problem. Good Luck!!

Meet the Author
Walter Johnson Concreteily
Walter Johnson

I’m a concrete contractor by trade and have been working in the industry for over 25 years now. I’ve seen (and done) it all when it comes to concrete, and I love sharing my knowledge and experiences with others who are interested in learning more about this amazing material. In my spare time, I enjoy spending time with my family, fishing, and watching NASCAR races.

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