I just noticed a crack in my basement windowsill and wall that I don’t believe was present when we bought this 20 year old Wisconsin house three months ago. The crack begins at the windowsill, then “stepladders” down the wall (although does not reach the ground) along the grout lines. There appears to be no water seepage from the window, or the crack. I have not been able to assess this window/wall from the outside because it is beneath our deck.
Do I need to have my house evaluated structurally? Is this crack of concern? Should I have this crack professionally sealed? Should I contact the home inspector who inspected the house prior to purchase?
I have linked the pictures for visuals. Any advice would be appreciated!
It appears from your photos and explanation your crack is what is called a stair step crack in only the mortar joints. This is usually the result of uneven settlement on either side of the crack and normally is not of serious or immediate concern. (However if your having trouble sleeping at night get a pro out to evaluate.) This could be the result in change in bearing or loading or a soft spot in the soil. Weather conditions, faulty gutters, or any other changes to the house could cause this or seismic conditions for that matter.
First you should monitor the crack to see if there is any more movement or not. Measuring, photos or a simple trick of placing tape over the crack in various spots and cutting the tape so you have a slit for measurement. If there is no more movement after several months you can easily fix the crack by cleaning out the grout joints and re grouting. Of course you still have the problem of sealing the exterior of the foundation as the crack most likely has broken the exterior seal. This will obviously be more difficult but if you have no leaks may not be an issue.
If the wall is still moving or if you notice horizontal movement, the plane of the wall separating you may want to have an engineer look at it however it still may not be anything to be overly concerned about.
If the crack was not there as you say when you purchased the house, there was nothing for the inspector to note and an issue like this can not be fore-casted as to when or if it may happen or where. Most foundations, if not all, at some point will crack at least in a minor fashion due to shrinkage. Modern poured foundations reinforced with more steel usually fare better but still may show hairline cracks due to the drying out of cement from its wet state when poured.
To help matters, make sure the drainage from rain, snow melt is directed away from the building and that the gutters are operating and draining away from the building properly.
Hope this helps a bit.