Frame the bottom shelf with an angle so that the water striking the window will run away from it.
Installing a basement window in a concrete wall.
Most modern homes are made out of concrete blocks which can make fitting a basement window seem very difficult in actuality installing basement windows is very easy as long as you have the right tools and materials.
Flash the entire wood casing using the proper primer.
Secure the window in place by installing double threaded concrete screws along the sides and top of the window.
Install window in the flashed opening and leave adequate space all around the window for insulation.
Build a wood casing screwed to the concrete opening.
The sashes easily come out through the inside.