Floors and floor joints
A vulnerable place for water seepage is the joint between the foundation wall and the floor. Look closely at this joint as you walk around the entire basement. Water stains and efflorescence are an indication of seepage. (See FIG. 11-8.) You might find silt deposits at the joint. This is also an indication of some degree of seepage. The fine silt is in suspension in the water as the water seeps in from the exterior. When the water evaporates, the silt is deposited. If you find evidence of water seepage through the joint between the floor slab and the foundation wall, you should record it on your worksheet for later correction. The joint should be sealed with either hot tar or a hydraulic cement.
Cracks tend to develop in the floor slab near the base of metal columns. Look for these cracks and any other cracks in the floor slab. Specifically, look for water stains, efflorescence, and silt deposits. Cracks in basement floors are a common phenomenon and are generally caused by slight settlement or shrinkage in the concrete. Usually they are of no concern other than the fact that water can seep through them. Therefore, they should be sealed. However, if the cracks are extremely wide or show evidence of heaving, they are of concern and should be checked further. In all probability, a cracked and heaved floor slab is the result of water pressure being exerted on the underside of the slab by a high water table.
Some homes have a cleanout and trap for the house waste line located in a pit below the basement floor slab. The bottom of the pit should be dry. If it is wet, it is an indication of a high groundwater level or a crack in the drain line. Occasionally I find that the top of the cleanout is open. (See FIG. 11-9.) It should normally be plugged. Some homeowners remove the plug so that the open cleanout can function as a drain if the basement becomes flooded. This is definitely not the way to eliminate the water in a flooded basement. If the basement periodically floods and there is no drain in the floor, a sump pump can be installed in the lowest section of the floor. The water can then be pumped out of the basement. With the cleanout plug removed from the top of the house trap, the possibility exists that if the sewer line becomes overloaded (as is the case in some communities), sewage can back up and flood the basement. I know of several homes where this has happened. It was quite unpleasant.
Some people lose interest in a house when they find a sump pump in the basement. They think that the house has water problems. That is not necessarily so. There might have been periodic problems resulting from a seasonal high water table, but the sump pump might have controlled the water level. Or the pump might have been installed when the house was built in order to prevent a problem. To determine whether there still are problems, you must look beyond the sump pump. Look for signs of water seepage.