window  well
A below grade window well that's back pitched
towards the house with no drainage system.

A very common source of water on basement floors that sometimes show little or no signs of entry are basement windows. Poor grading away from the foundation and/ or a roof leader too close to a window well can allow large volumes of water into the window well area and possibly rise above the level of the basement window. Lack of flashing or sealant around basement windows can allow water to enter below the visible sheetrock in a finished basement and run down the foundation wall behind the framing. In these cases, water will settle out to the lowest areas of the foundation floor slab. Water moving behind the wall with few signs of moisture presence is not uncommon for basements that experience intermittent water issues. In a case where there is a large area of carpet that is soaked after a brief but heavy rain, window wells are usually the root source of the water because large volumes of water simply won’t travel through wall cracks or pipe penetrations that quickly. Inspect the window well, it should be fitted tight to the foundation and sealed so that water cannot pass through. Many foundations have cracks that extend from the window openings and can run as far down as the footing.

Any change in the foundation wall, such as a window, vent or door opening, is a structural weak point that can be prone to movement and subsequent cracking. If the grade allows water back towards the window well area, then the crack can allow water to enter below the surface soil. The grade around the window well should be sloped away and about 2" of the well should be showing above the final grade of the soil. The basement window itself, whether it is a typical hopper style window or a full egress window, should be sealed so as not to allow air and water around the outer frame where it contacts the concrete. Proper window, well installation, grading and a good quality window well cover installed correctly will ensure trouble-free basement windows.