Basement window wells keep soil away from foundation windows and block water while permitting light into the basement. Find out your local building codes regarding basement windows and the installation of window wells. A permit usually is required for construction.
Some windows wells are decorative masonry structures custom-made of stone or concrete blocks. Most people elect to go with prefabricated window wells constructed from heavy-gauge galvanised steel, which are available in various heights and widths. At minimum, a window well must be as wide as the window and should protrude at least 3 feet from the foundation wall.
Determine the elevation for your window well. Usually, the top of the well should be at least 6 inches from the bottom of the siding, but 2 or 3 inches above grade. Dig out the ground for the new window well. Make sure you have plenty of room to work, so the dimensions of the hole should two times the size and depth of the window well you are installing.
Also, excavate the trench for your drainage pipe. Run water from the window well away from the foundation, or connect to the current foundation drainage system.
When you're ready to install the widow well, position the well against the foundation wall and mark the points for the mounting holes. Use a masonry drill bit to create the fastener holes. Caulk the area with mastic and secure the window well to the foundation. Use pea gravel to backfill the perimeter. Once you have the drainage method complete, put about 12 inches of pea gravel below the base of basement window well. You can also put 2 or 3 inches of gravel at the bottom of the well.
If you window well doesn't drain properly, excess water can run through the window back into the basement. Consider constructing your window well with a drain that connects to the foundation drain, which runs around the perimeter of the house. Make sure that the soil in the well is several inches below the basement window. The soil should be sloped toward the drain. Cut out a small section of the drain. Install a "tee," and a riser for the drain connection. Wrap the new connections with landscape fabric. This will keep out dirt and debris.
Another approach is to construct a "stone under" drainage system. The trench must slope "downhill" or away from the well. Use 1-inch or smaller crushed stone or pea gravel as a bed for the 4-inch plastic drainage pipe used to collect the water. Install solid 4-inch pipe to carry the water away from the window well.