I discovered some foundation cracks last night in my 1936 brick colonial in Western Pennsylvania.
The foundation is ungrouted tri core concrete block.
The prior owner allowed rose of sharon bushes to
spread too close to the house, and they are growing in
the basement window wells. I knew this, and it was on
my list of things to take care of, but apparently too
far down on the list.
The window has cracked, and when I moved things in the
basement to access the window, I discovered two cracks
in the concrete block under the window. The cracks are
about 1/4″ wide, are straight cracks that do not
follow the mortar joints, and are angled down and
toward the middle of the window (but don’t connect).
They look fairly fresh – no prior repairs, no paint in
them – so I am assuming the damage is recent.
I’m assuming the roots of the bushes caused this,
given no other signs of structural issues and the fact
that the cracks only extned about 4 feet down, and
don’t go to the floor.
Any advice or recommendations on how to repair this?
Replies
It sounds like the cracks are most likely due to the wall bowing inward. This can be caused by expansive soil, by ice in the well, or by vigorous root growth. You need to figure out and fix the cause, then simply caulking the cracks should be sufficient (since the cracks are primarily on the inside, not the outside).
If you want to move the wall back into place probably one of the outfits that specializes in this (using anchors that pull the wall outward) is probably worth considering.
No electrons were harmed in the making of this post.
Good point Dan--the wall could be pushed in and this can be verified by putting a level to check the plump of the wall. My home's foundation is only 8" block ungrouted with no rerods just a couple of pilasters. I noticed a lateral crack in the 2d course from the top and saw that the wall was out of plumb an inch and a half. So I and my two sons dug a trench outside 2' wide and all the way down to the footing and filled the void with pea pebbles. As soon as we had dug the dirt out the crack closed. The wall is still out of plumb but I don't expect it to get worse, but I could be wrong.
I'd suggest measuring the plumb condition of the wall with a four foot level. I typically use the plumb condition as a benchmark of the advancement of the problem. i.e. if it is still relatively plumb, perhaps little work is needed. If the wall is out of plumb by close to an inch or more, usually more significant measures are appropriate.
If the wall is being pushed in, it is most likely by soil pressure. Often water in the soil is a factor but it is the soil reaction to water that is the source of the pressure. The roots might exacerbate the problem but the primary source of such pressure will almost always be the soil. Clayey soils can be prone to this problem. Do you know much about the soil type present?
If the wall is being pushed in, and the wall has cracked because it is not strong enough to resist the pressure, I'd be concerned about additional pressure development. Often the wall should be strengthened as well as the pressure being reduced.
Thanks for the comments. Upon further investigation, I am finding some evidence of prior repairs.
The soil is clay, but the grade slopes toward the back of the house fairly steeply (the basement floor is at ground level in the back of the house). There does not appear to be a drainage problem.
The wall seems to be reasonably plumb, and does not appear to be bowed. There is also a crack in the concrete floor at that point, extending toward the middle of the house. That crack appears to be a normal expansion crack, at least to my untrained eye. I have not found any other cracks in the basement walls.
I also do not see any expansion joints in the concrete block wall. That wall is 22' long. Is that long enough to need an expansion joint? Might this be a case of the wall making it's own joint? BTW, the cracks are about 18 feet from one end of the wall, 4' from the other.
Thanks.
I don't think the Rose of Sharon are responsible for the cracking. They typically do not have the heavy roots needed for that . As far as making a mess in a window well, that they could do, especially if it's nearby and filled with water etc.
Your wall problem is probably due to soil/water combination, or it could be something as simple as poor mortar joints. I would have someone local come in and look at it. Be careful about who you get. Some of these hacks that deal in basement waterproofing will come in and try to tell you the building will collapse unless you pay them lots of money to fix it. I might even consider an engineer, but that's probably overkill given your circumstances.
Your comment about the earlier repairs means this has been ongoing - for how long? As far as putting in expansion, that is typically not done on basement walls or floors. Some people prefer to put an expansion joint around the perimeter of the floor where it meets the wall. I personally do not agree with that practice.
Don K.
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