Let me start out right away by saying that I am NOT a fan of windows in basement foundations, UNLESS the basement was intended in the original design as living space. Windows in the latter case are usually larger and in many cases intended to be alternate escape routes during emergencies. These windows are also usually insulated glass and of a better quality.
Windows in the former case are usually relatively small and are usually single-pane and relatively cheap. I guess they are supposed to offer some light into the basement and, since many can be opened, are apparently intended archaically to provide basement ventilation. They don’t, particularly in the modern home. I am especially not in favor of basement of cheaper basement windows because they are a security hazard. As cheap as most are, they could be easily compromised and allow a route for an unwanted to enter the home. If you think someone could not get int through the window, think again.
So, what does that discussion have to do with window wells? Pretty much every time I perform an inspection on a home with below-grade cheaper basement windows, I find water stains on the foundation wall beneath the windows, indicating that water has leaked through the windows. In these cases, water in the window well has gotten deep enough to partially submerge the window and then enter the basement around or through the window. If this problem happens often enough, windows with steel frames will rust through and windows with wood frames will rot.
Let me step back and talk about the basic construction of a PROPERLY installed window well. Window wells provide a space around the window to let in light and provide adequate room to maintain the window. (Most require periodic painting, window replacement and possibly caulk.) Most of the current window wells are a plastic or galvanized metal, and form a semi-circular space around the window. However, I have also seen window wells constructed from stone, concrete block and wood. Most window wells are 18″ to 24″ deep.
Manufactured window wells are supposed to be fastened to the foundation wall and should be caulked to prevent water intrusion through the gap between the well and foundation wall. The well wall should be above the grade at least three to four inches; but it also has be extend several inches below the window opening the foundation. Note that I did not say the window frame; I meant below the concrete edge of the opening. If stone or other materials that cannot be fastened to the foundation are used, I believe that landscape fabric with a layer of gravel should be installed over the outside joint between the well wall and foundation to prevent soil entering into the well through the gap. Just this past week, I witnessed a case where soil had extensively eroded into the window well through the gap between the well wall and foundation, partially plugging up the drain opening. Heaven only knows how much soil entered into the drain line.
Each well should have a drain, which is usually three or four inch PVC pipe, although I have also seen corrugated, non-perforated drain pipe used. The drain line should have a screen or strainer to keep larger debris out of the line where it could eventually clog the line, particularly leaves and grass clippings. The top of the drain should be two inches or, even better, more below the window opening in the foundation, again not the window frame. Pea gravel should cover the floor of the well to prevent soil erosion and mud constantly splashing up on the windows and foundation. BTW, NO other drain lines should be run into the window well from elsewhere, ESPECIALLY downspout drain lines. (I would not have mentioned it if I had not seen it myself.
Now, what about that drainage? Where should it go? In many cases, the window well drain line is run to the footing drain. I do not favor the window wells draining to the footing drain because debris from the window well could eventually plug up parts of the footing drain line, and that drain line is extremely important in many cases for preventing water intrusion into the basement. I first wrote that they could be tied into the downspout drain lines. After thinking about that arrangement, I decided that was not a good idea. If the downspout drain line plugged up, water could backflow into the window wells if their inlets were lower than the downspout drain line inlets. The best arrangement would be to run a separate drain line for the window well drains. This line could be tied into the downspout drain line if the tie-in were far enough below the window well drain line inlets to prevent backflow into the window wells.
I emphasized that the opening to the window well drain line should be inches below the opening in the foundation rather than the window sill. The reason is that in many cases, water leaks into the basement around the window frame, particularly beneath it. I have seen cases where the window frame has had the dickens caulked out of it on the inside, and just as well seen my share of leaks despite the caulk. What the homeowner usually does not realize is that on the outside, water has gotten into the gap between the foundation and the window frame. Over time, this water rusts metal frames and rots wood frames. Furthermore, gaps in materials form what we call a capillary gap which tends to hold the water in place even after the water in the window well has drained away.
One way to prevent, or at least slow down, water intruding through basement windows is to install glass block windows. These are basically mortared in place and provide about as much water intrusion prevention as concrete block. More importantly, glass block windows are more secure than most single-pane basement windows. If you still want a window vent, they are available for glass block windows. You can even provide an opening for a dryer vent, just be sure to put it higher in the window to prevent water entering through it should the window well flood. A word of caution, though, glass block windows CANNOT be installed if the window is an escape route. Those escape windows are required by building codes. I am talking about replacing the cheapy, single-pane windows.
Before I leave this subject, let’s talk maintenance. I have seen my share of wells nearly filled with leaves, grass clippings and trash. I have also seen small pastures in them; that is, a lot of vegetation. Creatures also have a bad habit of getting trapped in the wells—usually frogs or turtles, but the latest edition to the cats who run my house was also apparently born, and abandoned, in one of mine. My point is that window wells need probably as much maintenance as gutters. They have to be kept clean to prevent debris and vegetation clogging the drainage system. You should keep them clean if for no other reason to be able to periodically check your windows. One final note, if I have not convinced you to change to glass block windows, make sure that plantings around the foundation do not block view of the wells. Should an intruder choose that route into the home, at least make it possible for someone to see him/her. While your at it, maybe you should check the lock on the basement door.
Criterium-Cincinnati Engineers 