The most common basement cracks we see all over New England are the cracks off of a corner of a basement window, or one off the "step down". This is where the concrete goes from about 8' to about 6' and the concrete steps down.
These cracks are common because this is the weakest part of the concrete. In residential construction, they don't put re-bar going horizontal in the concrete for additional strength. And, these are weak points and stress points that often crack. Ninety percent of the time this is not a structural issue, but it is an issue for water infiltration, odor, cold, insects and the smell of organic material breaking down.
Because these basement foundation cracks are so common we can decide between two methods. One is to drill holes along the crack every 6 inches, put ports in, and fill these with closed cell polymer resin. Another method is to put a material into the crack and then a weave carbon fiber mat on top of that. In each case, the repairs are warrantied.
For more information, contact A1 Foundation Crack Repair.