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Robert E Lee

Tree roots

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At one of todays inspections there is an oak tree approx. 5-6 feet from the foundation of the house. The house was built in 1972, and this tree most likely was there at that time as it has about an 18 inch diameter. The client and I were talking about this tree and the possibility of damage to the foundation (not even a hint of a crack in the mortar at this time). While I've always read about the potential of damage to a foundation due to nearby trees, I've never run into such damage. What have some of you seen when trees are allowed to grow near the foundation, and what is the likely hood that this one may become a problem?

Robert E Lee

GENERAL Home Inspections

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General Lee,

I don't put too fine a point on this issue. An oak tree matures at over 100 feet. I don't think it belongs within 6 feet of the house, and always advise clients to have them removed. It's never going to be cheaper or easier to remove it than it is today. In my practice, it is unusual to see tree roots damage a foundation, but branches and trunks either abraid, or fall and hit houses commonly, and gutters are perpetually clogged by falling leaves and acorns.

Nothing good, and plenty of bad stuff will result from having an oak (or any other large tree) that close to the house.

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I've never seen roots damage a foundation from pushing or heaving against it. Ever. Trees are a lot sneakier than that. Trees are looking for water & light, not mortar, brick, or concrete.

A huge oak tree drinks anywhere from 100-300 gallons of water a day; if there's drought or dry conditions, it sucks the soil totally dry. The lack of any water causes soils to settle (smart folks say it "subsides"). Footings settle, & foundations crack. Takes a long time, but the tree surely damages the foundation. The official term for this phenomenon is "soil dessication".

Personally, I'd rather see a house settle than to cut down a 100 year old oak. Professionally, I advise my customers that settlement is a substantial concern, and that the tree should probably be removed.

If the house has been there long enough to see that there aren't any problems related to subsidence, I'd prune back any branches that might whack the house, but otherwise, I'd leave it right where it is.

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Hi All,

About two miles from my place there's a little brick ranch on a side street just up from Lake Washington with a 150 tall fir growing about 3ft. from the corner of the foundation. Across the street and up the hill are about 5 or 6 homes that can't get a view of the lake because of that fir.

When I inspected it, I crawled underneath it and found a root about 5 inches in diameter had cracked the uphill corner of the foundation and was growing into the crawlspace and had lifted the house and sills about an inch off that foundation at that corner. During the inspection, a couple of the neighbors came down from up the hill. They were eager to meet the client. Seems they'd been trying to get the occupant to cut down that tree for years but he refused. My client, a young fellow in his twenties, told them to talk to his agent. I figured that, knowing about the foundation, he'd be happy to get that damned tree out of there.

A couple of years later I bumped into him waiting to be seated in a local restaurant. Since the tree was still there, I asked him what was up with the tree. He explained that the neighbors regularly come down off the hill and offer him a little more each time to remove the tree. I asked him why he didn't - pointing out that it's damaged his foundation and is actually stressing the house. His answer: He's waiting until their figure is high enough to both remove the tree and repair the home.

That was about 6-7 years ago. That damned tree just keeps getting bigger and I bet it's blocking the view of at least 7 or 8 neighbors now. Why he hasn't removed it is beyond me, but I sometimes worry that the danged thing might, since the roots are obviously not gripping as well as they should on the foundation side, one day fall into the street and, in the process, knock that house partly off the foundation.

I'd love to be able to get into that crawl and see what things look like today in there.

ONE TEAM - ONE FIGHT!!!

Mike

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In our area, trees next to the foundation either means there is bad news, or there will be.

Check out this site and browse through their PDF's. This is a think tank of Engineers located here in Houston. This association specializes in slab on grade foundations.

One of the papers had some good pictures of trees vs. foundations, driveways, sidewalks and a garage.

http://www.foundationperformance.org/te ... apers.html

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Slab on grade is a different story; never see them, but can imagine a tree a few feet away would lift it up & mess it up badly.

I suppose the young guy and his tree are still waiting for the better offer. I hope he never gets it.

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Jeez Kurt, thanks a lot! Imagine if that damned thing decides to go down across the highway and dislodges the house from the foundation. The way the world is today, I'm liable to receive notice that I'm being sued for not predicting such an event when I inspected the home for him. [:-headach

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I guess one never knows. Do you think that it could actually cut loose it's grip & fall over? If I honestly thought that, I'd probably send the guy a letter telling my concern & recommending he remove it.

It'd break my heart though. Any folks that'd complain about a tree "blocking their view" apparently don't know what to look at.

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Originally posted by Jim Morrison

Nothing good, and plenty of bad stuff will result from having an oak (or any other large tree) that close to the house.

I always warn clients about potential problems and recommend removal if they're too close, but there is one benefit to having them. Down here we call it "shade", and in the summer we treasure it.

Brian G.

High 90's Every Day and in a Drought As We Speak...SEND RAIN! [:-crazy]

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An engineer friend told me that that you do not want any tree closer to the house than it is tall. The worst invasive tree I have ever seen is the Sycamore.

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Originally posted by Scottpat

An engineer friend told me that that you do not want any tree closer to the house than it is tall. The worst invasive tree I have ever seen is the Sycamore.

That's just silly. Sounds like personal folklore. If that were a problem, the 157 year old house I grew up in wouldn't have survived; our house was ringed by 120+ year old oaks & maples. What about all those fine old homes in Savannah & Charleston? They've got big trees in their yards, right? I suppose some of them are problems, but can you imagine Charleston w/out trees? Horrible thought....

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Originally posted by Scottpat

An engineer friend told me that that you do not want any tree closer to the house than it is tall. The worst invasive tree I have ever seen is the Sycamore.

And that's why we keep engineers locked up in cubicles. We don't want them running around loose where they could harm others or themselves.

- Jim Katen, Oregon

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My grandparents house has an oak 12 feet from the foundation that was probably germinating sometime around 1700. It's 20 feet in circumference 5 ft off the ground. When I was a kid, the trunk had a big rotten hollow spot maybe 2 feet wide and six feet high which my Dad carved out and then filled with concrete.

The scar on the trunk today is no longer visible; the tree has healed completely. I'll admit I get some pleasure knowing that the tree has some defense against a chainsaw.

The house was built in 1800 or so and the foundatuion is no curvier near the tree than it is anywhere else.

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Niiice..... That must be a magnificent tree.

My cousin has a smooth skin Beech tree on her property w/similar size characteristics; it has to be at least 175+ years old; a remnant of the climax forest that covered western Michigan. It doesn't do anything to her foundation other than shade it & make moss grow.

Hardwoods have better manners than some conifers I know. Pesky pine trees seem to like to push stuff around.

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Originally posted by Scottpat

An engineer friend told me that that you do not want any tree closer to the house than it is tall. The worst invasive tree I have ever seen is the Sycamore.

It doesn't take an engineer or a rocket scientist to figure out that if a tree is farther away from a house than it is tall, then it can't hit the house if it falls over. My guess would be that's his reasoning, and it's good advice if you want to reduce the risk of the tree causing damage to the house to zero. But most of us are comfortable with bearing some level of risk. I might mention that fact to my client to inform him of the risk, but stop short of recommending a tree be taken down simply because it was closer to the house than it was tall (assuming the tree has no obvious signs of disease or decay). The client can weigh the risk vs. enjoyment of the tree and decide.

Regarding the tree's root system, it extends out to roughly the spread of the tree's branches (in other words, where the shadow line would be if the sun was directly overhead). However, the roots out that far are the little feeder ones, not the kind that would move foundations, but the kind that like to find their way into your house sewer line or your leach field piping as they search for water.

The big honking roots are closer to the trunk. They're the ones you see still attached when the tree is uprooted and falls over. Mature (not ancient) oaks, maples and pines I've seen around here that have fallen over have roots sticking up in the air about 12-15 feet from the trunk. So a rule of thumb that a large tree should be at least about 12-15 feet away from the foundation sounds about right to me (to reduce the risk that the tree roots would grow large enough at the foundation to damage it).

Of course a mature tree growing that close will likely have large branches which overhang the house, so if the branches fall, or if the tree falls over into the house, it could damage the roof or framing (but the foundation would probably be fine).

At my own home, there are three large red oaks near my house, one about 2 feet in diameter located 6 feet from the corner of my 30 year old CMU block foundation, and the other two are about 3 feet in diameter and about 14 feet from the foundation. I have no cracking or damage to the foundation walls visible in my basement. The one 6 feet from the house will be taken down this summer, as I feel it is too close to the foundation, and I don't want to let it get any larger before bringing it down. The other two will remain, and will probably grow better because they were being crowded by the one that will be taken down. They overhang the house, but if they fall, that's why I have homeowner's insurance. I'll enjoy the trees and the house, and pay my insurance company to bear the risk.

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I have seen lots of large live oaks (1 to 3 feet diameter) next to slab foundations, and many were there when the house was built. Apparent foundation damage from these trees is rare; roof and fascia damage is another story.

Anyway, I have heard it said that the tree is looking for moisture and nourishment and there is very little of either under the slab. Therefore the tree roots don't grow under the slab foundation and no damage results. I'm not an arborist, but it makes sense to me.

Another consideration is that the tree sucks a tremendous amount of moisture from the soil daily. If the tree is removed soil moisture conditions are dramically altered, and in Central Texas expansive clay soils, that can result in heaving clay soils that will damage a slab foundation.

In my reports, I always commented on the tree and the possibility of damage to the house (roof and fascia), but I never recommended removing the tree. If the buyer was concerned, I'd pass the buck to a structural engineer and an arborist and let them fight it out. The arborist always said save the tree; the engineer would worry about future damage, but was usually hesitant to recommend changes because nobody knew what the result might be.

Around here a large oak on the lot, even next to the house, is worth thousands in appraised valve.

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In Maine-160 years old Fed. Colonial. Old tree next to the foundation lifted the rubble and sill 5+". New owner cut down the tree and chipped the roots. Town was pissed-tree dominated that side of the house and driveway. New? foundation positioned and new kitchen and family room installed. Siding saved and reapplied. I think the tree was there and some old yankee built an addition and carriage house too close. Boy --old houses are fun![:-banghea

Jack Ahern Needham on the Charles and Bridgton,Maine

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"Anyway, I have heard it said that the tree is looking for moisture and nourishment and there is very little of either under the slab. Therefore the tree roots don't grow under the slab foundation and no damage results. I'm not an arborist, but it makes sense to me."

Paul...

About 12 or 13 years ago, I saw a heaved slab in a house with a slab-on-grade foundation. Since the house was 40 or so years old, I said, and wrote, something stupid like "the movement likely won't continue". Gosh I said some idiotic things when I first started. Anyway, I was greener than the large tree next to the house, not even realizing the tree's roots were the culprit of the heaval.

Fast forward 10 years...my prior Client can't sell the house. Three home inspectors with three different buyer's all flagged the *abnormal and quite serious* structural movement. Naturally I got a call from my old Client.

After meeting him at the house again, I realized what I missed the first time...roots from the large tree next to the house obviously had heaved the slab. And, thank goodness, my stupid ten-year-old statement had held; the movement did not continue. Thank goodness for mature trees. Anyway, I recommended a review by a structural engineer to add *meat* to the root assumtion. The engineer concurred, wrote a fancy report, the Client showed the report to the next buyer, and voila!

May be rare, but perhaps there was a water source under the house. Goodness, that was the most sleep I ever lost over an inspection issue.

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Trying to remember your question...

This house of yours with a mortared block foundation has a greater chance of a major issue with nearby mature trees because, unlike integrated poured-concrete foundation/floor systems, roots can find their way into cracks in the mortar, where they can grow and damage things as they do. Your choice of inspector now becomes more critical in getting a quality assessment that will help you avoid or prevent such a failure.

There used to be an excellent inspector on this forum from Lexington, John Bain, perhaps he won't mind driving over to help you. He's about as good as they get.

Marc

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Check with the local bylaws.

These days, in a suburb, you don't just walk up to your tree and cut it down. But, you can prune it. The best way to know what is going on is to dig down to the footings along that side and cut any roots you encounter.

Then replace all that old perimeter drain pipe. The roots will be in there.

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