Why you may wake up to a soaked floor 

Many times, you will find a house whose floor tends to get soaked in water after it rains. Not because water enters the house through an opening, but because the floor somehow allows lets in water through the concrete. 
Normally, this happens when someone constructs a house in a wetland and according to experts, it does not only weaken the foundation of the house but also creates a greasy surface.  

Compression 
James Mutyaba, a builder, explains that the main reason floors get wet is because of compression. When warm steamy air from the 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 compression, the floor becomes darker and results into efflorescence in the long run and the  ground develops white patches  caused  when water  had previously been absorbed  into the concrete  floor slab,” he says 

Rising water vapour
Mutyaba says that rising water vapour is also another reason why your floor gets wet. It is possible that the moisture is not coming from the air at all but rising from the ground. Water vapour tends to move from moist areas to drier areas since concrete is absorbent.  
“If you live in an area with relatively soggy soil, the builder should install a moisture vapor barrier before pouring the concrete. Unfortunately, this doesn’t always happen because people fear extra costs and some builders are not well equipped to identify the outcome,” he says 

Cracks in your foundation
People that build in wetlands are likely to end up with wet floors regularly if they have cracks in the foundation; water always finds the cracks and makes its way to the house’s surface. 
“If your floor beams are not properly connected to the foundation walls, it can allow the water to move, and in turn, cracks are formed.” 
Mutyaba says that if water is not directed away from your foundation and accumulates against the foundation walls, that pressure can force the water into the walls, creating cracks. The moment these cracks exist, water can enter your basement through them and you find your floor wet.

Unsuccessful grading
Ineffective grading can also cause wetness of the floor because groundwater often makes its way into the basement due to poor grading. The ground around your foundation should slope away from the house not towards it.
“If the draining is in the wrong direction, obviously water will collect against your foundation and eventually make its way inside. This often happens when fill dirt around your foundation isn’t properly compacted.  You have to make sure that water doesn’t stop around your foundation,” he says.