Roots and foundations

L

Leafguy

New member
What are your guys typical answers for clients when asked about roots penetrating into the house foundations?

For me I tell people unless we dig around the foundation there is no real way to tell if it is affecting it. I do talk about root barrier systems as well.
 
It's quite common here in Florida for roots to damage foundations. Most homes are slab on grade, no basements, so roots can easily get under the slab and grow. High water tables and a long growing season exacerbate the problem. We also see a lot of sidewalk and driveway damage due to roots. I'll recommend barriers as long as the distance is sufficient. Other wise its removal or just live with it.
 
I usually tell them there is nothing in your basement that the tree is interested in. I live in a colder climate and most have poured foundations. I have only seen one house damaged by a tree and it was a volunteer poplar that had collapsed the basement wall with movement. Pretty amazing engineering though, obviously no roots on the house side and it was a 20" tree. I have a pic somewhere of it.

As far as roots breaking sidewalks and driveways - put the slabs or asphalt in on properly compacted substrate and there is little problem with roots as far as I can tell. The streets have no root problems as they are highly compacted. On a sandy soil, i'd bet you would have trouble...
 
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I'll recommend barriers as long as the distance is sufficient. Other wise its removal or just live with it.

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One other option is pruning; just dig down and cut the darn things, just like clearing the roof isn't it?

It seems the options that involve getting dirty always go to the bottom of the list, even when they make the most sense.
 
studies show just as many broken sidewalks where no trees are present. A good, reinforced slab is unlikely to be damaged by a tree. More likely, shifting soil will allow the slab to move, which might lever it over some fulcrum (which may or may not be a tree root) and damage it. This happens in Austin all the time (major clay soils here). Some friends were house shopping a while and finally stopped looking for an undamaged slab; they realized there was no such thing, and began looking for one that had been repaired correctly.

Next time you see a damaged piece of concrete, take a moment to note how much reinforcement it contains.
 
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studies show just as many broken sidewalks where no trees are present.

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I don't see that in my world. Can you please provide citations to those studies?
 
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I'll recommend barriers as long as the distance is sufficient. Other wise its removal or just live with it.

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One other option is pruning; just dig down and cut the darn things, just like clearing the roof isn't it?

It seems the options that involve getting dirty always go to the bottom of the list, even when they make the most sense.

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A temporary solution, at best. Roots, like branches, do grow back after cutting.
 
At the ISA Conference in Winnipeg last fall, one of the main speakers was not a tree guy at all, but an architect. This architect happened to have a keen interest in trees. He came out very strongly with studies to back it that properly installed concrete infrastructure does not conflict with tree roots. Even though many srborists argued with him, he adamantly maintained his position that tree roots cannot crack sound concrete. That fact that he was coming from a discipline asually on the other side of the argument was intriguing and held my interest. I wish I could remember more of it, and who the speaker was. then I could perhaps cite some references.
But I agree with Fireaxe that tree root would not normally be interested in your basement, unless it was already cracked and the root was seeking something, perhaps oxygen.
Roots seek perhaps the easiest path available, but maybe its not that simple. They also seek moisture and oxygen.
 
I also, as usual, can't remember where this comes from but IF the substrate that the asphalt or concrete is sitting on ground is properly compacted, the roots can't get through it. I just had the discussion with a homeowner over the weekend about a badly messed up driveway. I kept pointing to the public street as an example of a place where the compaction was too great for the roots to work with or was effectively sealed against moisture or air. The number 1.6g/cm sticks in my head for some reason. Most residential stuff is on completely or halfway compacted "soil".

Heavy vehicle traffic could crack on a root fulcrum - hadn't thought of that...
 
Nora, I believe you are refering to Jim Urban, a landscape architect(UGH!) that has done extensive work relating to urban trees and infrastructure. He has published "Up By Roots" which goes much deeper(no pun intended) into the subject than he does at conferences. He has developed the Silva Cell technology for trees planted in extreme urban situations. He is scheduled to hold a day long seminar in Atlanta sometime soon I believe.

Getting back to the question at hand, a number of years ago I did a Silver Maple removal that had a ton of top roots going everywhere. When I ground out the stump and top roots, I followed several toward the house foundation.These roots were easily 5 to 6 inches in diameter when the came in contact with a narrow sidewalk about 6 feet from the foundation. The roots essentially stopped at the sidewalk and did not affect the foundation at all. Granted the area was a heavy clay area which I'm sure had an effect.
 
In my experience, roots tend to follow the path of least resistance. I've done a lot of air spading around foundations, sidewalks, walls etc. I have never seen a root go through a foundation wall. Can't say it never happens but with todays poured foundations, it seems unlikely.
 
I don't think a root can GROW through a foundation, it's not a muscle. I think that can grow in a space so confined that sooner or later, something will give.

It's evident to me that roots are often the driving factor in foundation and sidewalk damage but it's not the root's fault. All it does it grow and reach nutrients, that's it's job.

Somebody put in a concrete something or other and then compacted the soil or created some other barrier condition. The root winds up in between concrete and a hard place. The cumulative pressure is huge because those cells keep on dividing. Earthquakes are caused by the same sort of slow steady pressure between plates.
 
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A temporary solution, at best. Roots, like branches, do grow back after cutting.

[/ QUOTE ]Yes, and roots, like branches, typically grow back from many points, not one.

Therefore, they do NOT fill the same area quickly.
Regrowth is far more diffuse.
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A temporary solution, at WORST. A long-term solution, quite often. And as others have noted, the soil around foundations is typically compacted and infertile, and roots stop short of the precious structures.
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I was just called out for a pre-home purchase consult, specifically for two large doug-firs near the house. All was well with the trees overall, except for the mulch and soil buried one, which the potential HOs will unearth.

There was a 2.5-3" root under the (seemingly shallowly poured) foundation. We don't freeze much here, so the frost line is relatively shallow at 12".

I just told her to dig around the outside of the foundation and cut it cleanly.

I wondered why it was growing under there, unless it was there before the shallow trenching for the foundation and/ or water was under the house. I mentioned that she should look into diverting water away (the inspector said to get splash blocks. huh???) from the foundation. Kinda in a low spot.

I did spot a crack in the foundation around the corner from the root that the inspector didn't. (nice work professional house inspector!)
 
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