After a humid night, water vapor in the air will come into contact with the cooler concrete floor and will condense into morning dew.
What causes concrete to sweat?
SSS or sweating slab syndrome is a phenomenon where moisture intermittently develops on the surface of an interior concrete slab. When warm air comes into contact with a colder temperature concrete slab, the condensation will build up on the surface and can commonly be defined as concrete sweating. The combination of temperature swings and humidity build up cause the concrete to sweat.
Concrete sweating, also known as sweating slab syndrome (SSS), refers to condensation that develops on the surface of the concrete. It is directly related to the dew point. “If the surface of a floor slab is colder than the dew point temperature of the ambient air above the slab, moisture will condense on the surface of the slab. This condition, commonly called “sweating,” typically occurs when warm, moist air flows into a building that has relatively cool floors.”
Kanare, H.M., “Sources of Moisture”, Concrete Floors and Moisture, page 15.
Why is concrete sweating problematic?
Concrete sweating make concrete slippery and can be dangerous on larger concrete slabs with a lot of traffic.
How to stop concrete sweating
- Dry out the room by air movement: a high volume low speed fan works well.
- Turn down the air conditioning/turn up the heat to keep the concrete floor temperature and the air temperature at similiar levels.
- Use a dehumidifier to remove moisture from the air and reduce the condensation.
- Use a penetrating sealer to seal the concrete and keep out moisture. We recommend using a concrete densifier first as a primer followed up by a penetrating concrete sealer.
It is important to use a penetrating concrete sealer as soon as possible so that you do not have to deal with mold or mildew issues which are a result of concrete sweating.
One of the best solutions to combat concrete sweating is to use a chemically reactive concrete densifier followed by an impregnating, penetrating sealer.
The Lithi-Tek 4500 is first used as a primer to reduce the porosity of the concrete.
By using a penetrating, water repellent sealer, the Siloxa-Tek 8510 impregnates the concrete making it less susceptible to concrete sweating.