Leaky Window & Door Bottoms

How Do We Deal With Leaky Door And Window Bottoms?

A common place for leaks in foundations is at the bottoms of basement windows and the bottoms of the upstairs doors.
When a concrete basement wall is poured, the area where there will be windows or doorsills is blocked out. These window and door cutouts are always the same depth–about a foot below the top of the concrete wall. The windows and doorsills do not sit flat on the foundation wall. There is always a place on top of the wall and below the basement window that is on a bit of a bevel. You may notice this if you go down to the basement and look up at a basement window. Most of my customers look at the cut-outs in the wall and don’t realize there are actually two separate parts. We have the foundation wall, which is actually flat on top, and the part that the window sits on which is beveled. This bevel is adjusted by the carpenters and the bricklayers for the proper elevations.

The leak problem is actually caused by the area on the bevel below the window. The corners by these cut-outs are naturally places where the concrete is less strong to begin with, and the cut-out has mortar sitting on top of the foundation with a window or door frame sitting on top of that. When there is a layer of mortar sitting on top of a separate layer of concrete, a crack can happen due to the fact that the expansion coefficient between the concrete of the foundation wall and the mortar which holds the window, is just a little bit different. In other words, the two shrink and stretch in response to temperature changes at different rates. A split can form between the mortar and the cement because the two are not locked together, and eventually open, because nothing is holding them together.

Generally, a crack forms over a period of years.




This job on an office building was done like a window bottom. If outside dirt is high, we have to change things.

There may be no problem with this crack at all, except when the homeowner changes the landscaping on his house. Homeowners can bring in additional dirt, plantings and wood chips, etc., as they change or add to their landscaping. They may bring the dirt higher than the level of the basement windows. Where there is dirt, there is moisture. Where there is moisture up against walls there may be leaks. The landscaping changes the drainage. Instead of going away from the house, rainwater can pond near the house. If there is a crack in the wall at this point, and poor drainage, you are just about guaranteed basement water problems.

Say there is a horizontal crack underneath the windows 4 to 8 inches below the dirt. After a heavy rain there could be gallons of water sitting against the basement wall just looking for a place to go. We have seen some pretty serious flooding from these two areas. I think the moral of the story is to not raise the dirt outside against the house. The consequences is to do some basement waterproofing.

We at Oakbridge have a tried and proven method of sealing these two areas that is not too expensive and doesn’t really take a lot of time, so call us at 586-703-0112 and we can clear up your problem. We guarantee our work, so call us.

Author: Robert B McGuire