Soil subsidence and trees

Roller · 10th September 2007, 08:02 AM

The trouble over here Ekka , some of the street trees here are over 200 years old, big old London Planes, root barriers won't work on them, so the only option is the chop, and that means even if a building has no signs of subsidence at all. Fair enough prehaps, I don't know the answer, sit and wait , only act when you're starring at 1'' wide cracks running down the wall!

I know one thing every single consultant when presented with clay soil and a tree within influeincing distance reccomends a TD

Roller · 10th September 2007, 08:16 AM

chech this firm out , what on earth do they charge!

Trees get criminal treatment - Press Release - Press and Communications - Newcastle University

Sean Freeman · 10th September 2007, 10:46 AM

We have had a similar DNA ID service available here following research at Melb Uni, though that was back in 2005, not sure if it is still being done there, was costly $500-$900 starting price (I think from memory...please don't get mad Melb Uni if thats wrong

)

Steve, if you're faced with a situation over there when you need other practical options than the removal valuable (some would say priceless!) vet trees try either Cheshire Woodlands Poynton, or the ArborCentre in Bath they are both excellent consutancy firms where the emphasis is the real situation between tree and environment rather than any prejudicial starting point.

Ekka · 10th September 2007, 12:52 PM

If the trees were there before the building then the building should be engineered strong enough to withstand the subsidence ... but in saying that maybe when the tree and building were on the scene the tree was much smaller.

Problem here in Australia is insurance companies do not pay out on subsidence. It comes out of your pocket to underpin a house.

bob w · 18th December 2007, 05:42 PM

Quote:

I thought I had posted this before but reading back through couldn't find it so apologies if you've seen it before, its from about 7yrs ago and by Bob Wulkowicz.

Thanks for the reference and for remembering some of my mutterings.

Heres another URL...

http://users.rcn.com/bobw.enteract/UKSubsidence2.2.html

Bob W.

Ekka · 18th December 2007, 07:28 PM

Hi Bob and welcome.

I read it all.

In Brisbane here we are in a pretty bad shape from drought.

Our dams for 2million people are down to 20%, they were down to 16% but recent rain had a small top up.

SEQWater - Dam Operations & Maintenance

Problem here is poor engineering which didn't consider clay soils and poor attitudes to trees and the species selection and location has led to lots of houses cracking.

The traditional rainfall was around 1200mm a year. I suppose the average in drought is 500mm. However it has been a couple of years of below average rain. That coupled with the fact that our primary dams for water are located to the west which is a lower rainfall area anyway.

Why do they build dams in low rainfall areas I hear you ask?

Because this is the smart state .... just having a dig.

I came from Adelaide in South Australia, average rainfall 550mm, in drought maybe 250mm, and they're sitting on 79% capacity.

On this map you just click the city and get the dam levels.
H2Overview - Dam level Map

So, it's about managing resources, collecting water where it rains, and being able to water. Due to water restrictions trees/gardens only allowed bucket watering certain times.

So you can imagine, drought, landscape neglect, houses cracking, engineers and geotechs loving it and under pinners booming. Pretty hard to stand up against an engineers report especially when they pull out some standard we dont have!

Now during all of this not many trees died really, sure a few did but not like say the beetle kills in USA or Dutch Elm Disease etc.

Anyway, the things I noticed here was no paths around houses and vegetation right up to the walls. Also a termite problem. Houses built up to late 70's didn't have to get the roof water into a drain, most just dump it straight out the down pipe onto the lawn/garden etc.

No-one really gave much thought to drought, heck it rains all year around and mainly in summer, so soil is always damp and dams always trickle filled.

The immediate solution for most people was installing rainwater tanks for roof run off. I did this to, I collect 3500 litres from 20mm of rain, I use this to top up the pool. State govt gives you $1000 as incentive to put in a tank greater than 3000 litres. Water is the answer, as you say rehydration.

Other thing is mulching, reducing that sun exposure.

Sean Freeman · 18th December 2007, 07:30 PM

Hello Bob and welcome

I was impressed with that article back in 2001 when I first read it and it still impresses me today.
You wouldn't be surprised I suppose to know that there are still a great many who believe and propogate the idea that trees are devilish organisms wantanly sucking water from our parched soils causing millioins of $$'s of damage to valuable realestate....
ah well you can tell a mug, just can't tell them much

azrael · 19th December 2007, 08:40 AM

Hi Bob...welcome
Good article .... rationale impressive ...and so eloquently put.
I can see you are passionate and committed to care of trees for their enduring landscape contribution.
I

TOO.
Azrael

Oldtimer · 19th December 2007, 09:05 AM

So far I have learned a lot from this discussion as usual. Here is a more stuff to add to the discussion. I have a fairly large tree about 10 feet from the side of the house. ( About 70 feet tall and 2 feet dbh). The tree was definitely there before they built the house. Recently I have noticed a small crack along the brick face on the side of the house ( the brick wall is not structural but ornamental mostly). Anyway I personally do not care about the cracks or the tree being there since it is my favorite tree for Recreational Climbs and it shades a large portion of the house in the hot Texas Summers. BUT what would happen in a few years when I will try to sell my house and the buyer decides that the tree must go and the foundation or wall re-leveled???? I can always tell the buyer to take a hike right!

Should I even try to excavate a barrier trench along the wall and try to install a Barrier to the roots? Is it even worth the efforts or the cost involved?? The roots are now completely under most of the foundation for the house so other than killing the tree the damage is slowly going on as the tree looks for water from the sewer lines under the house foundation. So far there is not obvious impact on the drainage pipes but the roots feeders will get there eventually. I will not hold anyone liable for your opinions so fire away.

Options anyone?????

By the way a few houses down from mine there is another house and that one has a tree that is actually touching the foundation and they cut a small piece in the roof line for the tree to pass by. That is cool! I will try to get a photo but there is not obvious damage to their foundation so far.

Ekka · 19th December 2007, 05:20 PM

It really depends on a few factors from an engineering point of view.

1/ Soil type, you need to know what you got.

2/ Engineered foundation, what have you got.

3/ Structure of the house. Our house is brick veneer, common here. The strength of the house is in the timber frame and the masonary or brick is a facade to a degree. It bears no loads.

4/ Type of tree.

Most people here when they buy a house get a building inspection, your house would be picked up for the tree and the wall. Even if the wall were repaired so it was unnoticeable the builders report would likely nail the tree anyway. But that's here, not where you are.

You need to get a pic of that crack ... close and distance, if need be trace the crack in MS paint etc so we can see it.

Builders can come out and check the levels with laser, they'll know where it's upheaval or subsidence.

Then it's suggested a soil test to know what you exactly have. Then it's also suggested the soil test is also done opposite side of house to a non affected area as a "control" hole. Check and compare for moisture and plasticity/strength.

Could be as easy as watering.

The root barrier should be about 3' away from the house too, but not done with backhoe or trencher. Need a clean cut, some use water cutters but there are machines similar to a concrete cutter where a rotating blade cuts a clean slot.

Oldtimer · 20th December 2007, 08:21 AM

"The root barrier should be about 3' away from the house too, but not done with backhoe or trencher. Need a clean cut, some use water cutters but there are machines similar to a concrete cutter where a rotating blade cuts a clean slot" said Eric.

I think that if we were to dig that close to the tree and remove all the roots to place the root barrier I am afraid that a couple of things would take place.

First the amount of damage to the root system will devastate the tree so may as well remove it and be done with it.

Second I am afraid that disturbing that much soil on one side of the tree will leave it unbalanced without strong root support on that side and easier to tip over in a strong wind storm either falling in top of the house or pulling in the other direction away from mine and into the neighbors yard. So in my view it is not a very simple solution either way for the owner of the house or for the tree.

The final alternative (cross the fingers here). Find a buyer that likes trees as much as I do and do not think that the damage to the brick veneer is a big deal and they will sign up in the dotted line without problems and hand over the check. ($250K more or less but who is counting!).
The way properties are changing hands in this city it could be possible!
Who knows.

I will try to post a photo of the tree. The crack on the brick is too small to see in a photo. It kind of follows along the grout used to keep the bricks together so it can be easily fill-in with a similar color material and very few people would even notice it. (tricky eh!)

The tree is a Cedar Elm (Ulmus crassifolia)
COMMENTS from Google search:
Found growing beside Ashe Juniper ("cedar") in Hill Country, hence name; wood hard and heavy, knotty; often planted as shade tree; if you need a vertical tree this on is more tall than broad, each one has its own individual shape.

Thanks for all the free advise. It is nice that you guys are willing to provide this type of info and long distance consultation. Thanks

Ekka · 20th December 2007, 01:37 PM

Well, according to Dr Coder's document about structural root plate here Tree protection zones| Critical root zones| Critical Root Radius| AUSTRALIA

If the tree is 24" DBH then the distance is only around 6' which fits in the plan.

However, you can plan and prepare this cut.

What you'd do is spoil the roots the other side of the cut and the other side of the tree. I've added a diagram.

I perhaps would encourage optimal root growing conditions away from the tree and between the tree and the root barrier just good conditions. My reasoning for such is to reduce the severity of stress after the cut between the barrier and the tree and to reduce the concentration of roots against the barrier by encouraging better conditions the other way. Also the majority of roots will be the feeders, you can lure them.

This way the tree should cope fine.

Oldtimer · 21st December 2007, 02:57 AM

That is a great diagram of my tree situation. Thanks for putting it together. I was thinking that this tree also may have a main deep penetrating central core of roots ( Tap root ) holding the tree upright and the peripheral lateral roots even the ones going under the house foundation are more of a feeding mechanism for the tree. They are smaller in diameter and mostly absorb water. Your recommendation to start treating the other side of the tree away from the house with more deep fertilization and watering will force (encourage) the tree roots to move into that area and leave the ones under the foundation starved from growth. The soil in this area are rather shallow, so deep root penetration is not very likely. Fractured rock can be found a few feet deep all over this property.

It is weir how the trees put roots in areas that we assume are not good for root develoment. In another tree (Live Oak) near the street. There is a tree betweeen the street and the sidewalk and I lifted a large piece of side walk and found a solid mat of feeder roots under it. I tried to cut some of them to reset the big piece of sidewalk back in place and they are solid like a mat so I gave up at left the side walk a little out of level ( about 3 inches lifted) and live with it rather than cause a bunch of damage to the tree roots. I was also afraid that the root damage would increase the chances of getting Live Oak Disease (Oak Wilt) that eventually got to the tree anyway and it is in bad shape now. I refused to treat it with Alama ( a roof Fungicide) microinjection but so far it has survived and maybe it will make it. Two other large Oaks already had to be removed from the yard becase of the disease that is pretty much killing all the oaks in our subdivision. You can actually see it moving down the street killing the trees! Pretty sad because that was the main reason why I purchased this house. The 3 Large Oaks in the from yard and the main reason why I became a Recreational Tree Climber just to be able to hang around my trees and now 2 are gone!

Ekka · 21st December 2007, 06:57 AM

Main thing the tree roots get under a slab is moisture as there's less evaporation of the soil. Also, could be a more stable temperature due to the insulating effect of the house above.

Bit different with paths as not as much weight to lift compared to a house.

When I say prepare roots for the cut it means more so surface treatment, mulch, organic additives like seasol, blood/bone etc.

I'd just work on that, if anything for deeper root work I'd be just aerating.

Mulch is the real key though.

Oldtimer · 23rd January 2008, 08:36 AM

Hey, Ekka That picture that you posted of the outside of the building looks exactly like the outside of my house!
cracks2.JPG (249.1 KB, 9 views)
I am not about to cut my tree down just because of that. There are people that hate leaves from trees and they blame them for everything including their house foundation cracking and all it takes is some silly "engineer" to sell them the story that injecting a little bit of foam under the foundation will solve their subsidance/cracking wall problem. What a rip off!

Those trees in the photo are too far away from those foundations to be of much impact of those houses IMHO.

wulkowicz · 31st January 2008, 07:42 PM

I did a little digging and came across a post that speaks to a few issues here. It is changed a tiny amount to correct past tense, etc. since it is an antique, but I can theoretically edit my posts and escape complaints of plagiarism.

------------------------------------

Conference:
1) General Forum
From:
Bob Wulkowicz (bobw@enteract.com)
Topic:
Urban Myths and the Slaughter of Trees (1/1)
Date:
Saturday, September 15, 2001 10:35 AM

Original Message: non-invasive trees

http://www.oak-wood.co.uk/cgi-bin/an...u=1148&zu=1148

Posted by R. Richards , Sep 14,2001,11:53

I wish to plant a 20--30 ft. high screen of trees next to my garden wall and am concerned about the root systems damaging the wall and foundations. I wondered about False Pepper trees or Mimosa Trees
being ok and would be grateful for any suggestions from you. We live in the Costa Blanca area of Spain.

----------------------------------------------------

People have been planting trees next to their walls and buildings for a few dozen centuries.

In the past dozen years however, we have suddenly discovered what a threat they are to our structures. The surprise is not that we have found something new, but that it took us so long to do it.

The hysteria that abounds in the UK is a consequence of a 20 year protracted drought with a significant reduction in average rainfall, along with building practices and designs that never anticipated these conditions. The expectable actions of the insurance businesses who figure it is cheaper to cut down trees than fix up foundations are now coupled with the familiar human tendency to jump on an arboreal band wagon when there's money to be made.

The results are letters like yours where the writers are understandably concerned and are looking for advice. Once spread, the myths couldn't be beaten to death with a stick, let alone refuted by a simple examination of facts. Roots do not push through walls, but they will explore and may grow into existing cracks--and perhaps appear at first to have caused the cracks. But they did not; roots simply do not have the strength.

Roots cannot lift structures or buildings; they can't engage in those pressures and still stay alive. If they could, there'd already be an clever old farmer's trick of planting willows next to, or under, something that needed to be demolished. Well, there aren't any such techniques because roots can't do what the farmer would have wanted.

As a direct answer to your concerns, here is one of the very few overview studies done somewhat recently, this one from the UK by Cram and McLeod (Arbor, Research Article, AAIS 4/13/96 EXT), where we find two conclusions pertinent to your questions.

Regarding Primary growth which is a root pushing forward through the
soil or against an obstacle:

...growth of tree roots can occur over long distances, but roots cannot exert sufficient pressure to penetrate compacted soils or even soft masonry...

And as to structures and buildings, with Secondary or Radial growth which is the increase in diameter along the length of a root,

...the forces generated are not sufficient to displace loaded structures such as dwellings, or to force apart brickwork or drainage pipes.

--------------------

Now, in fairness to the readers, I have been campaigning against the misinterpretations of physics, engineering, and tree biology that give rise to the slaughter of trees and help spread of myths that cause the public unfounded worries about their trees.

I also cannot agree with a number of the civil engineering examples in the above study, but that is my task later to disprove or present alternatives. All that I ask now from any of us readers here is a fair consideration of the issues and healthy open discussions of the points of view.

At the present time in the UK, trees are clearly the enemies of people’s properties and vast sums of money are spent to cut them down.

In my efforts, I was frankly worried about the spread of this delusion to the States and also upset watching the needless felling of many innocent trees along with a corresponding cost to insurance companies and public agencies.

--------------------------------------------------

Tress do take moisture out of the soil. But so does any vegetation. An expanse of grass, without trees, is a remarkable extractor of water. All sorts of things will pull water out, or dry up a soil. Sunlight on bare earth
will obviously desiccate a soil; and ironically trees that are cut down out of fear will no longer provide shade that once significantly reduced full exposure drying.

When top layers of soil dry, no matter what the reason, the lower levels of the earth will move their moisture upwards to try to maintain an equilibrium of water over a distance.

Ordinarily, top levels were always replenished with the usual UK rains and the lower levels did not necessarily need to move their moisture up and away. Indeed, significant amounts of water have always been percolating and moving downward over millions of years. This process gave us our aquifers and underground rivers and the other geological products of gravity acting upon water in soils.

There had generally been a "natural" rhythm of rain that kept the soils at moisture levels we (and trees) had grown accustomed to over the many years. Now the UK has had a protracted drought, --"quite unnatural"--and there simply have been fewer rains to wet the ground and move that water downward. Whether or not there are trees, all soils will face the same future of drying when rain is denied.

There are a very few clay soils will expand and contract significantly with variations of moisture, and I do not wish to dilute this discussion with technical distinctions, but it is true that buildings and structures can be more vulnerable to problems on those soils. However there are many buildings built on those same soils that do not have any distress.

The difference? Often, the many decisions and designs by architects and builders, and then quality of construction work have determined the potential for future problems. There is no one to blame in a sense; no one anticipated the profound changes in the UK’s climate.

And any recent torrential rains were mostly channeled as runoff and could not percolate into the soils to replace lost moisture. Bringing water into the soils naturally might very well take about the same amount of time it took to lose the water. The processes are slow but are reversible.

A year or so ago, I proposed that we can now irrigate for both vegetation and buildings. It is a simple common-sense concept. The drought has been the enemy of both trees and buildings, but the victim trees are being cut down as if they are the criminals.

If we understand the need to keep soil moisture stable below the root zones of our plants and trees, as well as buildings above, we can control possible damage to those structures and buildings. If the present climatic
circumstances put buildings at risk, the most correct and obvious solution is to remedy the fundamental reason--the migration of soil moisture from under those foundations and footings of structures.

There are already a number of ways to do that; some are complicated; many are expensive; but all have the same goal.

I have put together a method that is simple, cheap and quick that has evolved from a system I invented to save trees during a drought. It works just as well for buildings as trees, and I’m still embarrassed I didn’t make the connection sooner.

In any case it is available to look at and can be found in this UK site either under my name or under the title, A Modest Proposal. One arborist remarked, “It can’t be that simple, can it?”

Well, it is exactly that. I intended to save trees from an unprecedented droughts in Chicago, and now perhaps if this is understood, I can
also save trees from an unnecessary chain saw.

I know that I will hit arborists in the pocket book with a reduction in felled trees, perhaps but practitioners should realize that they can sell irrigation services as well as chainsaw time. I simply want is to save the many magnificent trees that are at risk to myths, poor science, and aggressive salesmanship that feeds off the fears of the public.

I had decided to be aggressive as well and push these issues from a not-all-profit perspective. I consider myself a steward and so it must be part of my obligations to act in defense of trees. If I can save trees and save
money, perhaps that is exactly what i should be doing. Important issues often require an injection of passion, so I trust you’ll understand my intentions.

------------------------------------------

(To R. Richards)

Everything I have said applies to your home in Spain as well. You are correct to ask the questions and be prudent about possible threats of root systems. If builders and developers had been as
forward thinking when these older dwellings and structures had been built, we wouldn’t have so many of these problems.

The trouble is that the term “invasive root systems” has always been a description of a tree’s evolved ability to explore, and then collect water and nutrients.

It is not a description of any capacity to cause physical damage.

But it is now convenient and useful for those who would exploit our fears, building a persuasive pile of misinformation, pseudo-science and high-pressure tactics to convince us of the need for their services.

We will miss those trees that provided shade and shelter. And we should be embarrassed that we galloped so far already in a herd animal mentality into accepting a false diagnosis and a foolish remedy.

My best in your efforts,

Bob Wulkowicz
RR 2 Guysborough,
Nova Scotia Canada B0H 1N0
(902) 366-3000

Bob Wulkowicz
704 S. East Avenue
Oak Park, IL 60304
(773) 539-0003

bobw@enteract.com

The original report, done at the request of Paul Hawksford in the UK, is at:

http://users.rcn.com/bobw.enteract/UKSubsidence2.2.html

I will be revising it soon, tightening up my prose--if I’m capable of that--compressing the pictures , and making it faster to download.

Ekka · 31st January 2008, 07:58 PM

Quote:

Originally Posted by wulkowicz

Roots cannot lift structures or buildings; they can't engage in those pressures and still stay alive.

Bob, can you take a look at this thread/post.

Preventive design| tree planting selection guide

Oldtimer · 1st February 2008, 01:06 AM

I think that some trees are definitely able to push and shove foundations or porches up and out of alignment but as EKKA's photos show the tree was obviously planted in the wrong place and the homeowner should have noted early on the potential problem with the gum tree growing right next to the steps.

As global warming continues to show its impacts such as the reduction of rains in England or the uncontrolled floods in Bangladesh we will have to learn to cope with these problems on a case by case basis.

The problem with the one solution to solve all the problems is neither practical nor realistic. Cutting all the trees near a house not only will increase the soil temperatures and water loses from deeper horizons but it will increase the likelihood of cracks in foundations showing up more regularly specially on those soils with high content of clay. ( high shrink/swell capacity). Here in Texas large expanses of land previously under-cultivation have been bulldozed down and made into new subdivisions covered with cookie cutter track houses built on poorly designed and constructed foundations that show cracking and fractures even before the buyer signs up the paperwork. These are soils that should have never been covered with those houses but the destruction continues in order to provide the "American Dream" of owning a house outside town in the "country" to everyone. The problem is that city dwellers are not familiar with the problems of living in the countryside such as having to keep the soils around the house foundation moist even in dry conditions to prevent shrinking and swelling with extreme changes in soil moisture regimes.

wulkowicz · 16th February 2008, 04:57 AM

Depending on my mood, I could use the following photo for or against the claim of subsidence. Clearly, the sidewalk defletions are serious and would warrant the removal of the trees.

Wait a minute, those aren't trees; they're signs.

Now whatta we got?

Signs cause subsidence?

Oldtimer · 16th February 2008, 05:15 AM

Quote:

Originally Posted by wulkowicz

I could use the following photo for or against the claim of subsidence. Signs cause subsidence?

By looking at the photo I was thinking that was a natural way to slow down the traffic for safety reasons.

It looks better than the "speed Bumps and Speed Humps" they have tried in Austin.

One of the most ridiculous ideas was to plant gardens in the middle of the road and make little "round-abouts" in the middle of small intersection streets to force vehicles to slow down while crosing the intersection. After a few (drunk) drivers

run into the flower beds a few times they are considering removing them now.

Your tax dollars at Work!

A speed hump is a gradual rise and fall of the pavement surface along the roadway extending across the pavement width. Generally, speed humps used on residential streets are 12 to 22 feet long with a maximum height of 3 to 4 inches. Speed "humps" are different from speed "bumps", which are seen in many private parking lots.

Ekka · 16th February 2008, 07:47 PM

I remember back in Adelaide (notorious for active clay soils) there was a double lane road going past K-Mart near Parafield Gardens area.

It was wavey and you'd get that feeling in your stomach when driving over these waves.

So, finally the roads dept decides to rip it up and fix it.

Every day I travelled this road, for years. So I watched carefully.

The ripped it up and excavated a little, new rocks/road base etc and rolled the living crap out of it. They were meticulous and finally went down the tarmac and it was open again.

It drove like ice, beautiful. Then after a few months it was bumpy. About a year later the undulations were back. After 2 years you'd swear nothing was ever done and it was just as bad as in the first place.

Go figure that out, weird, the soil was mighty unstable. There were no trees about either.

They recorded in some test in Adelaide up to 75mm of soil movement up and down throughout the year. Obviously this one was a lot worse.

Ekka · 22nd June 2008, 01:45 AM

Well, here's another bad example.

200-year-old trees to be chopped down - Northampton Chronicle and Echo

Quote:

Saturday, 21st June 2008

200-year-old trees to be chopped down

Centuries-old trees in a Northampton street are being cut down to protect houses built only 25 years ago.
Six 200-year-old oak trees and one 120-year-old ash tree are being chopped down in Green Lane in West Hunsbury.

Mavis Wilmshurst, who lives in neighbouring Greenglades, said she was horrified at the decision.

The retired nurse said: "I thought they were just going to cut parts of them but then I realised they were going to chop them down completely.

"They have not made any attempt to underpin the houses to protect them. One of the houses has been under-pinned and the tree is still standing so why can't they do that with all of the affected houses?"

She believes the houses, which are very close to the old trees, should never have been built.

She said: "I just walked past one of the trees being chopped down and it almost reduced me to tears. Those trees are so huge and so beautiful. I'm not Northamptonshire born and bred but I know this was an original coach route from the canal, and it has historical significance for the town. Those trees are part of that and the houses were built too close to them."

Northampton Borough Councillor Trini Crake (Lib Dem, Boughton Green), cabinet member for environment said: "It is disappointing that we are forced to fell seven trees in Green Lane and they will be a loss to the area."

She said the trees had been causing subsidence problems for several years and added: "We have exhausted every alternative to felling these beautiful trees. This means we are forced to remove the trees at the earliest possible opportunity.

"After checking for nesting birds and other wildlife, specialist tree contractors are now felling the trees," she said.

"We have a duty to care for the local environment and will always fight to protect assets like trees. However in situations where a tree causes structural damage it will have to be felled when all other options have been exhausted."

A spokesman for the authority added he could not confirm if and when the trees would be replaced, but said as the soil had a high clay content and needed time to recover there were no plans to replace them in the immediate future.

Sean Freeman · 22nd June 2008, 09:31 AM

Sometimes you feel like its one step forward and five back! This kind of rubbish makes me almost give up on people it really does....200yr old trees with probably twice that left in them (maybe) removed. No there's no engineering solution.....rubbish there's always an engineering solution just comes down to cost and the will to do it.

There was a list of steps that Veteran trees should be subjected to before any consideration of any kind of damaging works is made...of course I can't find the darn thing now...but it summarises basically everything I have written on this topic before....

1) Review geotech data
2) Review foundation specs for buildings affected
3) Examine foundations and sub soil
4) Undertake comprehensive geotech assessment of the building and the sub soil
5) Establish if stability changes or cyclic or progressive
6) Install level monitoring/crack monitors
7) ID the species of the roots (if any) effecting the subsoil around foundations
8) Assess suitability of moisture barrier around building foundation
etc....

Now these steps may have been followed or some of them I don't know...though I doubt it.
There is literally heaps of things to be done long before anyone even considers picking up a saw, its too easy to simplistically point to the big old trees and say yes they are causing this foundation problem. When the trees under suspiscion are veterans, and of significance to the local (or wider) community the burden of proof should be on those wanting to damage the trees, since it is not a simple causal relationship that has not been proven incorrect.

Ekka · 22nd June 2008, 05:16 PM

25 years ago makes it built 1983

So in 1983 what were the specs? Did they have to reinforce for subsidence and trees? Here the foundation regs for trees came out 1995.

The other issue is the TPZ for development site tree protection simply is not the same as the subsidence perimeter. You might for example build 5m away from a large tree however the area for soil subsidence influence might be 10m etc. And as you know here they use tree ht as factor. If tree is 100' tall then it must be 100' away ... or top it to the right distance.

This is where we are in 2008 with trees and buildings, yet, for every soil engineer, structural engineer and arborist there perhaps 300 lawyers coming out of Uni.

Like the hoop pine I had to report on, which I never did. It was the anti-subsidence tree but earmarked for removal. When all else fails blame the tree. The good thing about many Queensland homes is they were built on stilts and out of wood. So they had movement but never cracked. The ole double brick is the worst, brick veneer next best and wood the best for reactive soils.

Do you remember the Kansai International Airport? I watched a documentary on it, amazing engineering. They drilled and drilled but couldn't find rock so they came up with a great foundation idea. They thought it would settle some 15m in 50 years but it settled around 11m in 5 years. To overcome they had alarms set to the building with huge jacks and would literally go around jacking it up. No shit, first floor would become ground floor, the entire building was modular with doorways being like slots and a fake ceiling.

Here's a ppt on it http://ecow.engr.wisc.edu/cgi-bin/ge...nalairport.ppt

Anyway, morale of the story is there were no trees to blame it on.

Oldtimer · 23rd June 2008, 04:48 AM

This is kind of funny. The reason why the houses were built there in the first place was because of the beautiful trees that "naturaly" were growing there, So, now trees are a "nuisance" to the owners and it is time to kill them-trees.

I hope their Electric utility bill triple or more now that they will not have the trees nearby to cool off their stupid-sinking-in-the-ground-houses!

Hopefully their land will become a desert and blow away in the wind.

Some land developers and home owners just do not have a sense!

Ekka · 23rd June 2008, 08:36 AM

You'd think they'd have taken more consideration for 175 year old trees, a subterranean retaining wall/root barrier would have done the trick.

Done it · 3rd July 2008, 11:24 PM

Quote:

Originally Posted by Oldtimer

This is kind of funny. The reason why the houses were built there in the first place was because of the beautiful trees that "naturaly" were growing there, So, now trees are a "nuisance" to the owners and it is time to kill them-trees.

I hope their Electric utility bill triple or more now that they will not have the trees nearby to cool off their stupid-sinking-in-the-ground-houses!

Hopefully their land will become a desert and blow away in the wind.

Some land developers and home owners just do not have a sense!

You're spot on there. Are you really an Agronomist? Must be a great job.

Just today I heard they found a bee in the Hunter Valley, NSW [wine grape growing area +] that comes from Southern Europe/Mediterranean that can be a huge problem. Evidently it got here in soil somehow as they are ground dwellers. I'll try and follow up on it, as bees here are having enough problems as it is.

Ekka · 3rd July 2008, 11:30 PM

We got those stupid fire ants up here too, came in soil.

Done it · 4th July 2008, 08:55 PM

Quote:

Originally Posted by Ekka

25 years ago makes it built 1983

So in 1983 what were the specs? Did they have to reinforce for subsidence and trees? Here the foundation regs for trees came out 1995.

The other issue is the TPZ for development site tree protection simply is not the same as the subsidence perimeter. You might for example build 5m away from a large tree however the area for soil subsidence influence might be 10m etc. And as you know here they use tree ht as factor. If tree is 100' tall then it must be 100' away ... or top it to the right distance.

This is where we are in 2008 with trees and buildings, yet, for every soil engineer, structural engineer and arborist there perhaps 300 lawyers coming out of Uni.

Like the hoop pine I had to report on, which I never did. It was the anti-subsidence tree but earmarked for removal. When all else fails blame the tree. The good thing about many Queensland homes is they were built on stilts and out of wood. So they had movement but never cracked. The ole double brick is the worst, brick veneer next best and wood the best for reactive soils.

Do you remember the Kansai International Airport? I watched a documentary on it, amazing engineering. They drilled and drilled but couldn't find rock so they came up with a great foundation idea. They thought it would settle some 15m in 50 years but it settled around 11m in 5 years. To overcome they had alarms set to the building with huge jacks and would literally go around jacking it up. No shit, first floor would become ground floor, the entire building was modular with doorways being like slots and a fake ceiling.

Here's a ppt on it http://ecow.engr.wisc.edu/cgi-bin/ge...nalairport.ppt

Anyway, morale of the story is there were no trees to blame it on.

Yep, blame the trees. Our house is just an old 50's timber, surrounded by trees [I have posted some pics in that tree hugger thread] it creaks & groans, when it rains the back door jams, when it's dry the front door jams, it's clay/shale around here & brick houses crack, trees or no trees. Do you think people will listen, no way. I just get sick of trying to explain it.

Those fire ants are bad news but last I heard they were doing a good job on them. The bee is an Emerald Furrow bee, this is the interveiw I heard, if anyone is interested. Invading bee threatens Australian environment: scientist - ABC News (Australian Broadcasting Corporation)

It's not long but seems to take a while to come up, might just be my computer.

Ekka · 18th July 2008, 10:29 PM

Appears UK has made a new tree valuation method to increase the value of trees and clamp down on the subsidence claims.

Ancient oak in Surrey tree valued at £500,000 - Telegraph

Quote:

In London alone, more than 16,000 trees including some over 100 years old have been chopped down because of insurance claims in the past five years, although the London Assembly said that only one per cent of those removals were justified.

Britain's most expensive tree valued at £750k - Telegraph

Quote:

Its value has been calculated by a new system, to be used by councils, which takes into account the size, health, historical significance and number of people living near to a tree who can enjoy it.

The method, known as the capital asset value for amenity trees (Cavat), will soon be adopted by every local authority in the country to try and prevent trees being chopped down if they are suspected of causing subsidence to nearby buildings.

If a tree is deemed to be particularly valuable, extra engineering work will have to be carried out to prove that it is definitely the tree which is to blame for the property sinking, rather than other causes such as bad drainage or poor weather.

Hundreds of older, healthy trees are currently being felled by insurers and councils on the suspicion that they are causing damage to homes.....

Andy Tipping, chairman of the London Tree Officers' Association, said: "Often an insurer will point the finger at the tree, it is chopped down and then subsidence problems in a house persist.

"People are still not understanding that subsidence is a problem of buildings not trees. In many cases trees are not the main culprit. It's other reasons such as Victorian drains, poorly installed double-glazing or climate change."

PDF and XLS attached of the system and how to use it.

10th September 2007, 08:02 AM	#31
Roller Semi-mature vigorous tree Join Date: Feb 2007 Location: Suffolk UK Posts: 156	Re: Soil subsidence and trees The trouble over here Ekka , some of the street trees here are over 200 years old, big old London Planes, root barriers won't work on them, so the only option is the chop, and that means even if a building has no signs of subsidence at all. Fair enough prehaps, I don't know the answer, sit and wait , only act when you're starring at 1'' wide cracks running down the wall! I know one thing every single consultant when presented with clay soil and a tree within influeincing distance reccomends a TD __________________ www.arboraeration.co.uk Tree healthcare specialists covering the UK

10th September 2007, 08:16 AM	#32
Roller Semi-mature vigorous tree Join Date: Feb 2007 Location: Suffolk UK Posts: 156	Re: Soil subsidence and trees chech this firm out , what on earth do they charge! Trees get criminal treatment - Press Release - Press and Communications - Newcastle University __________________ www.arboraeration.co.uk Tree healthcare specialists covering the UK

10th September 2007, 10:46 AM	#33
Sean Freeman PDF King & Arborist Extrodinaire Join Date: Feb 2007 Location: Townsville Nth Queensland & Gold Coast Sth Queensland Posts: 2,149	Re: Soil subsidence and trees We have had a similar DNA ID service available here following research at Melb Uni, though that was back in 2005, not sure if it is still being done there, was costly $500-$900 starting price (I think from memory...please don't get mad Melb Uni if thats wrong) Steve, if you're faced with a situation over there when you need other practical options than the removal valuable (some would say priceless!) vet trees try either Cheshire Woodlands Poynton, or the ArborCentre in Bath they are both excellent consutancy firms where the emphasis is the real situation between tree and environment rather than any prejudicial starting point. __________________ Sean Trees are poems that earth writes upon the sky, We fell them down and turn them into paper, That we may record our emptiness. - Kahlil Gibran http://wanderingarborist.blogspot.com/ http://veterantreegroup.blogspot.com/ http://www.youtube.com/user/VeteranTreeGroup

10th September 2007, 12:52 PM	#34
Ekka Admin - Dip Arb & Hort & Seldom Wrong Join Date: Jan 2007 Location: Brisbane Posts: 9,792	Re: Soil subsidence and trees If the trees were there before the building then the building should be engineered strong enough to withstand the subsidence ... but in saying that maybe when the tree and building were on the scene the tree was much smaller. Problem here in Australia is insurance companies do not pay out on subsidence. It comes out of your pocket to underpin a house. __________________ TAS Training & Assessment Services\| Arb and Hort Training available here Free Online Tree Value Calculator by TreeWorld Free Online TPZ and SRZ AS4970-2009 Calculator by TreeWorld Free Online Tree Surface Area and Tree Volume Calculator by TreeWorld Free Tree and Green Industry Deep Link Directory ... Yes, I also SEO (Optimize) and build websites that fly high in Google Qualified Brisbane Tree Lopping \| Stump Grinding Brisbane Brisbane - Gold Coast Consulting Arborist, Tree and Arborist Reports \| Project Arborist

18th December 2007, 07:28 PM	#36
Ekka Admin - Dip Arb & Hort & Seldom Wrong Join Date: Jan 2007 Location: Brisbane Posts: 9,792	Re: Soil subsidence and trees Hi Bob and welcome. I read it all. In Brisbane here we are in a pretty bad shape from drought. Our dams for 2million people are down to 20%, they were down to 16% but recent rain had a small top up. SEQWater - Dam Operations & Maintenance Problem here is poor engineering which didn't consider clay soils and poor attitudes to trees and the species selection and location has led to lots of houses cracking. The traditional rainfall was around 1200mm a year. I suppose the average in drought is 500mm. However it has been a couple of years of below average rain. That coupled with the fact that our primary dams for water are located to the west which is a lower rainfall area anyway. Why do they build dams in low rainfall areas I hear you ask? Because this is the smart state .... just having a dig. I came from Adelaide in South Australia, average rainfall 550mm, in drought maybe 250mm, and they're sitting on 79% capacity. On this map you just click the city and get the dam levels. H2Overview - Dam level Map So, it's about managing resources, collecting water where it rains, and being able to water. Due to water restrictions trees/gardens only allowed bucket watering certain times. So you can imagine, drought, landscape neglect, houses cracking, engineers and geotechs loving it and under pinners booming. Pretty hard to stand up against an engineers report especially when they pull out some standard we dont have! Now during all of this not many trees died really, sure a few did but not like say the beetle kills in USA or Dutch Elm Disease etc. Anyway, the things I noticed here was no paths around houses and vegetation right up to the walls. Also a termite problem. Houses built up to late 70's didn't have to get the roof water into a drain, most just dump it straight out the down pipe onto the lawn/garden etc. No-one really gave much thought to drought, heck it rains all year around and mainly in summer, so soil is always damp and dams always trickle filled. The immediate solution for most people was installing rainwater tanks for roof run off. I did this to, I collect 3500 litres from 20mm of rain, I use this to top up the pool. State govt gives you $1000 as incentive to put in a tank greater than 3000 litres. Water is the answer, as you say rehydration. Other thing is mulching, reducing that sun exposure. __________________ TAS Training & Assessment Services\| Arb and Hort Training available here Free Online Tree Value Calculator by TreeWorld Free Online TPZ and SRZ AS4970-2009 Calculator by TreeWorld Free Online Tree Surface Area and Tree Volume Calculator by TreeWorld Free Tree and Green Industry Deep Link Directory ... Yes, I also SEO (Optimize) and build websites that fly high in Google Qualified Brisbane Tree Lopping \| Stump Grinding Brisbane Brisbane - Gold Coast Consulting Arborist, Tree and Arborist Reports \| Project Arborist

18th December 2007, 07:30 PM	#37
Sean Freeman PDF King & Arborist Extrodinaire Join Date: Feb 2007 Location: Townsville Nth Queensland & Gold Coast Sth Queensland Posts: 2,149	Re: Soil subsidence and trees Hello Bob and welcome I was impressed with that article back in 2001 when I first read it and it still impresses me today. You wouldn't be surprised I suppose to know that there are still a great many who believe and propogate the idea that trees are devilish organisms wantanly sucking water from our parched soils causing millioins of $$'s of damage to valuable realestate.... ah well you can tell a mug, just can't tell them much __________________ Sean Trees are poems that earth writes upon the sky, We fell them down and turn them into paper, That we may record our emptiness. - Kahlil Gibran http://wanderingarborist.blogspot.com/ http://veterantreegroup.blogspot.com/ http://www.youtube.com/user/VeteranTreeGroup

19th December 2007, 08:40 AM	#38
azrael Former Member Join Date: Dec 2007 Location: Earth Australia Posts: 243	Re: Soil subsidence and trees Hi Bob...welcome Good article .... rationale impressive ...and so eloquently put. I can see you are passionate and committed to care of trees for their enduring landscape contribution. I TOO. Azrael

19th December 2007, 09:05 AM	#39
Oldtimer Semi-mature vigorous tree Join Date: Jan 2007 Location: Austin TX Posts: 105	Re: Soil subsidence and Root from trees So far I have learned a lot from this discussion as usual. Here is a more stuff to add to the discussion. I have a fairly large tree about 10 feet from the side of the house. ( About 70 feet tall and 2 feet dbh). The tree was definitely there before they built the house. Recently I have noticed a small crack along the brick face on the side of the house ( the brick wall is not structural but ornamental mostly). Anyway I personally do not care about the cracks or the tree being there since it is my favorite tree for Recreational Climbs and it shades a large portion of the house in the hot Texas Summers. BUT what would happen in a few years when I will try to sell my house and the buyer decides that the tree must go and the foundation or wall re-leveled???? I can always tell the buyer to take a hike right! Should I even try to excavate a barrier trench along the wall and try to install a Barrier to the roots? Is it even worth the efforts or the cost involved?? The roots are now completely under most of the foundation for the house so other than killing the tree the damage is slowly going on as the tree looks for water from the sewer lines under the house foundation. So far there is not obvious impact on the drainage pipes but the roots feeders will get there eventually. I will not hold anyone liable for your opinions so fire away. Options anyone????? By the way a few houses down from mine there is another house and that one has a tree that is actually touching the foundation and they cut a small piece in the roof line for the tree to pass by. That is cool! I will try to get a photo but there is not obvious damage to their foundation so far.

19th December 2007, 05:20 PM	#40
Ekka Admin - Dip Arb & Hort & Seldom Wrong Join Date: Jan 2007 Location: Brisbane Posts: 9,792	Re: Soil subsidence and trees It really depends on a few factors from an engineering point of view. 1/ Soil type, you need to know what you got. 2/ Engineered foundation, what have you got. 3/ Structure of the house. Our house is brick veneer, common here. The strength of the house is in the timber frame and the masonary or brick is a facade to a degree. It bears no loads. 4/ Type of tree. Most people here when they buy a house get a building inspection, your house would be picked up for the tree and the wall. Even if the wall were repaired so it was unnoticeable the builders report would likely nail the tree anyway. But that's here, not where you are. You need to get a pic of that crack ... close and distance, if need be trace the crack in MS paint etc so we can see it. Builders can come out and check the levels with laser, they'll know where it's upheaval or subsidence. Then it's suggested a soil test to know what you exactly have. Then it's also suggested the soil test is also done opposite side of house to a non affected area as a "control" hole. Check and compare for moisture and plasticity/strength. Could be as easy as watering. The root barrier should be about 3' away from the house too, but not done with backhoe or trencher. Need a clean cut, some use water cutters but there are machines similar to a concrete cutter where a rotating blade cuts a clean slot. __________________ TAS Training & Assessment Services\| Arb and Hort Training available here Free Online Tree Value Calculator by TreeWorld Free Online TPZ and SRZ AS4970-2009 Calculator by TreeWorld Free Online Tree Surface Area and Tree Volume Calculator by TreeWorld Free Tree and Green Industry Deep Link Directory ... Yes, I also SEO (Optimize) and build websites that fly high in Google Qualified Brisbane Tree Lopping \| Stump Grinding Brisbane Brisbane - Gold Coast Consulting Arborist, Tree and Arborist Reports \| Project Arborist

20th December 2007, 08:21 AM	#41
Oldtimer Semi-mature vigorous tree Join Date: Jan 2007 Location: Austin TX Posts: 105	Re: Soil subsidence and trees "The root barrier should be about 3' away from the house too, but not done with backhoe or trencher. Need a clean cut, some use water cutters but there are machines similar to a concrete cutter where a rotating blade cuts a clean slot" said Eric. I think that if we were to dig that close to the tree and remove all the roots to place the root barrier I am afraid that a couple of things would take place. First the amount of damage to the root system will devastate the tree so may as well remove it and be done with it. Second I am afraid that disturbing that much soil on one side of the tree will leave it unbalanced without strong root support on that side and easier to tip over in a strong wind storm either falling in top of the house or pulling in the other direction away from mine and into the neighbors yard. So in my view it is not a very simple solution either way for the owner of the house or for the tree. The final alternative (cross the fingers here). Find a buyer that likes trees as much as I do and do not think that the damage to the brick veneer is a big deal and they will sign up in the dotted line without problems and hand over the check. ($250K more or less but who is counting!). The way properties are changing hands in this city it could be possible! Who knows. I will try to post a photo of the tree. The crack on the brick is too small to see in a photo. It kind of follows along the grout used to keep the bricks together so it can be easily fill-in with a similar color material and very few people would even notice it. (tricky eh!) The tree is a Cedar Elm (Ulmus crassifolia) COMMENTS from Google search: Found growing beside Ashe Juniper ("cedar") in Hill Country, hence name; wood hard and heavy, knotty; often planted as shade tree; if you need a vertical tree this on is more tall than broad, each one has its own individual shape. Thanks for all the free advise. It is nice that you guys are willing to provide this type of info and long distance consultation. Thanks

21st December 2007, 02:57 AM	#43
Oldtimer Semi-mature vigorous tree Join Date: Jan 2007 Location: Austin TX Posts: 105	Re: Soil & Trees & Foundation Damage That is a great diagram of my tree situation. Thanks for putting it together. I was thinking that this tree also may have a main deep penetrating central core of roots ( Tap root ) holding the tree upright and the peripheral lateral roots even the ones going under the house foundation are more of a feeding mechanism for the tree. They are smaller in diameter and mostly absorb water. Your recommendation to start treating the other side of the tree away from the house with more deep fertilization and watering will force (encourage) the tree roots to move into that area and leave the ones under the foundation starved from growth. The soil in this area are rather shallow, so deep root penetration is not very likely. Fractured rock can be found a few feet deep all over this property. It is weir how the trees put roots in areas that we assume are not good for root develoment. In another tree (Live Oak) near the street. There is a tree betweeen the street and the sidewalk and I lifted a large piece of side walk and found a solid mat of feeder roots under it. I tried to cut some of them to reset the big piece of sidewalk back in place and they are solid like a mat so I gave up at left the side walk a little out of level ( about 3 inches lifted) and live with it rather than cause a bunch of damage to the tree roots. I was also afraid that the root damage would increase the chances of getting Live Oak Disease (Oak Wilt) that eventually got to the tree anyway and it is in bad shape now. I refused to treat it with Alama ( a roof Fungicide) microinjection but so far it has survived and maybe it will make it. Two other large Oaks already had to be removed from the yard becase of the disease that is pretty much killing all the oaks in our subdivision. You can actually see it moving down the street killing the trees! Pretty sad because that was the main reason why I purchased this house. The 3 Large Oaks in the from yard and the main reason why I became a Recreational Tree Climber just to be able to hang around my trees and now 2 are gone!

21st December 2007, 06:57 AM	#44
Ekka Admin - Dip Arb & Hort & Seldom Wrong Join Date: Jan 2007 Location: Brisbane Posts: 9,792	Re: Soil subsidence and trees Main thing the tree roots get under a slab is moisture as there's less evaporation of the soil. Also, could be a more stable temperature due to the insulating effect of the house above. Bit different with paths as not as much weight to lift compared to a house. When I say prepare roots for the cut it means more so surface treatment, mulch, organic additives like seasol, blood/bone etc. I'd just work on that, if anything for deeper root work I'd be just aerating. Mulch is the real key though. __________________ TAS Training & Assessment Services\| Arb and Hort Training available here Free Online Tree Value Calculator by TreeWorld Free Online TPZ and SRZ AS4970-2009 Calculator by TreeWorld Free Online Tree Surface Area and Tree Volume Calculator by TreeWorld Free Tree and Green Industry Deep Link Directory ... Yes, I also SEO (Optimize) and build websites that fly high in Google Qualified Brisbane Tree Lopping \| Stump Grinding Brisbane Brisbane - Gold Coast Consulting Arborist, Tree and Arborist Reports \| Project Arborist

23rd January 2008, 08:36 AM	#45
Oldtimer Semi-mature vigorous tree Join Date: Jan 2007 Location: Austin TX Posts: 105	Re: Soil subsidence and trees Hey, Ekka That picture that you posted of the outside of the building looks exactly like the outside of my house! cracks2.JPG (249.1 KB, 9 views) I am not about to cut my tree down just because of that. There are people that hate leaves from trees and they blame them for everything including their house foundation cracking and all it takes is some silly "engineer" to sell them the story that injecting a little bit of foam under the foundation will solve their subsidance/cracking wall problem. What a rip off! Those trees in the photo are too far away from those foundations to be of much impact of those houses IMHO.

31st January 2008, 07:42 PM	#46
wulkowicz Semi-mature vigorous tree Join Date: Aug 2007 Location: NOVA SCOTIA Posts: 55	Re: Soil subsidence and trees I did a little digging and came across a post that speaks to a few issues here. It is changed a tiny amount to correct past tense, etc. since it is an antique, but I can theoretically edit my posts and escape complaints of plagiarism. ------------------------------------ Conference: 1) General Forum From: Bob Wulkowicz (bobw@enteract.com) Topic: Urban Myths and the Slaughter of Trees (1/1) Date: Saturday, September 15, 2001 10:35 AM Original Message: non-invasive trees http://www.oak-wood.co.uk/cgi-bin/an...u=1148&zu=1148 Posted by R. Richards , Sep 14,2001,11:53 I wish to plant a 20--30 ft. high screen of trees next to my garden wall and am concerned about the root systems damaging the wall and foundations. I wondered about False Pepper trees or Mimosa Trees being ok and would be grateful for any suggestions from you. We live in the Costa Blanca area of Spain. ---------------------------------------------------- People have been planting trees next to their walls and buildings for a few dozen centuries. In the past dozen years however, we have suddenly discovered what a threat they are to our structures. The surprise is not that we have found something new, but that it took us so long to do it. The hysteria that abounds in the UK is a consequence of a 20 year protracted drought with a significant reduction in average rainfall, along with building practices and designs that never anticipated these conditions. The expectable actions of the insurance businesses who figure it is cheaper to cut down trees than fix up foundations are now coupled with the familiar human tendency to jump on an arboreal band wagon when there's money to be made. The results are letters like yours where the writers are understandably concerned and are looking for advice. Once spread, the myths couldn't be beaten to death with a stick, let alone refuted by a simple examination of facts. Roots do not push through walls, but they will explore and may grow into existing cracks--and perhaps appear at first to have caused the cracks. But they did not; roots simply do not have the strength. Roots cannot lift structures or buildings; they can't engage in those pressures and still stay alive. If they could, there'd already be an clever old farmer's trick of planting willows next to, or under, something that needed to be demolished. Well, there aren't any such techniques because roots can't do what the farmer would have wanted. As a direct answer to your concerns, here is one of the very few overview studies done somewhat recently, this one from the UK by Cram and McLeod (Arbor, Research Article, AAIS 4/13/96 EXT), where we find two conclusions pertinent to your questions. Regarding Primary growth which is a root pushing forward through the soil or against an obstacle: *...growth of tree roots can occur over long distances, but roots cannot exert sufficient pressure to penetrate compacted soils or even soft masonry...* And as to structures and buildings, with Secondary or Radial growth which is the increase in diameter along the length of a root, ...the forces generated are not sufficient to displace loaded structures such as dwellings, or to force apart brickwork or drainage pipes. -------------------- Now, in fairness to the readers, I have been campaigning against the misinterpretations of physics, engineering, and tree biology that give rise to the slaughter of trees and help spread of myths that cause the public unfounded worries about their trees. I also cannot agree with a number of the civil engineering examples in the above study, but that is my task later to disprove or present alternatives. All that I ask now from any of us readers here is a fair consideration of the issues and healthy open discussions of the points of view. At the present time in the UK, trees are clearly the enemies of people’s properties and vast sums of money are spent to cut them down. In my efforts, I was frankly worried about the spread of this delusion to the States and also upset watching the needless felling of many innocent trees along with a corresponding cost to insurance companies and public agencies. -------------------------------------------------- Tress do take moisture out of the soil. But so does any vegetation. An expanse of grass, without trees, is a remarkable extractor of water. All sorts of things will pull water out, or dry up a soil. Sunlight on bare earth will obviously desiccate a soil; and ironically trees that are cut down out of fear will no longer provide shade that once significantly reduced full exposure drying. When top layers of soil dry, no matter what the reason, the lower levels of the earth will move their moisture upwards to try to maintain an equilibrium of water over a distance. Ordinarily, top levels were always replenished with the usual UK rains and the lower levels did not necessarily need to move their moisture up and away. Indeed, significant amounts of water have always been percolating and moving downward over millions of years. This process gave us our aquifers and underground rivers and the other geological products of gravity acting upon water in soils. There had generally been a "natural" rhythm of rain that kept the soils at moisture levels we (and trees) had grown accustomed to over the many years. Now the UK has had a protracted drought, --"quite unnatural"--and there simply have been fewer rains to wet the ground and move that water downward. Whether or not there are trees, all soils will face the same future of drying when rain is denied. There are a very few clay soils will expand and contract significantly with variations of moisture, and I do not wish to dilute this discussion with technical distinctions, but it is true that buildings and structures can be more vulnerable to problems on those soils. However there are many buildings built on those same soils that do not have any distress. The difference? Often, the many decisions and designs by architects and builders, and then quality of construction work have determined the potential for future problems. There is no one to blame in a sense; no one anticipated the profound changes in the UK’s climate. And any recent torrential rains were mostly channeled as runoff and could not percolate into the soils to replace lost moisture. Bringing water into the soils naturally might very well take about the same amount of time it took to lose the water. The processes are slow but are reversible. A year or so ago, I proposed that we can now irrigate for both vegetation and buildings. It is a simple common-sense concept. The drought has been the enemy of both trees and buildings, but the victim trees are being cut down as if they are the criminals. If we understand the need to keep soil moisture stable below the root zones of our plants and trees, as well as buildings above, we can control possible damage to those structures and buildings. If the present climatic circumstances put buildings at risk, the most correct and obvious solution is to remedy the fundamental reason--the migration of soil moisture from under those foundations and footings of structures. There are already a number of ways to do that; some are complicated; many are expensive; but all have the same goal. I have put together a method that is simple, cheap and quick that has evolved from a system I invented to save trees during a drought. It works just as well for buildings as trees, and I’m still embarrassed I didn’t make the connection sooner. In any case it is available to look at and can be found in this UK site either under my name or under the title, A Modest Proposal. One arborist remarked, “It can’t be that simple, can it?” Well, it is exactly that. I intended to save trees from an unprecedented droughts in Chicago, and now perhaps if this is understood, I can also save trees from an unnecessary chain saw. I know that I will hit arborists in the pocket book with a reduction in felled trees, perhaps but practitioners should realize that they can sell irrigation services as well as chainsaw time. I simply want is to save the many magnificent trees that are at risk to myths, poor science, and aggressive salesmanship that feeds off the fears of the public. I had decided to be aggressive as well and push these issues from a not-all-profit perspective. I consider myself a steward and so it must be part of my obligations to act in defense of trees. If I can save trees and save money, perhaps that is exactly what i should be doing. Important issues often require an injection of passion, so I trust you’ll understand my intentions. ------------------------------------------ (To R. Richards) Everything I have said applies to your home in Spain as well. You are correct to ask the questions and be prudent about possible threats of root systems. If builders and developers had been as forward thinking when these older dwellings and structures had been built, we wouldn’t have so many of these problems. The trouble is that the term “invasive root systems” has always been a description of a tree’s evolved ability to explore, and then collect water and nutrients. It is not a description of any capacity to cause physical damage. But it is now convenient and useful for those who would exploit our fears, building a persuasive pile of misinformation, pseudo-science and high-pressure tactics to convince us of the need for their services. We will miss those trees that provided shade and shelter. And we should be embarrassed that we galloped so far already in a herd animal mentality into accepting a false diagnosis and a foolish remedy. My best in your efforts, Bob Wulkowicz RR 2 Guysborough, Nova Scotia Canada B0H 1N0 (902) 366-3000 Bob Wulkowicz 704 S. East Avenue Oak Park, IL 60304 (773) 539-0003 bobw@enteract.com The original report, done at the request of Paul Hawksford in the UK, is at: http://users.rcn.com/bobw.enteract/UKSubsidence2.2.html I will be revising it soon, tightening up my prose--if I’m capable of that--compressing the pictures , and making it faster to download.

1st February 2008, 01:06 AM	#48
Oldtimer Semi-mature vigorous tree Join Date: Jan 2007 Location: Austin TX Posts: 105	Re: Soil subsidence and trees I think that some trees are definitely able to push and shove foundations or porches up and out of alignment but as EKKA's photos show the tree was obviously planted in the wrong place and the homeowner should have noted early on the potential problem with the gum tree growing right next to the steps. As global warming continues to show its impacts such as the reduction of rains in England or the uncontrolled floods in Bangladesh we will have to learn to cope with these problems on a case by case basis. The problem with the one solution to solve all the problems is neither practical nor realistic. Cutting all the trees near a house not only will increase the soil temperatures and water loses from deeper horizons but it will increase the likelihood of cracks in foundations showing up more regularly specially on those soils with high content of clay. ( high shrink/swell capacity). Here in Texas large expanses of land previously under-cultivation have been bulldozed down and made into new subdivisions covered with cookie cutter track houses built on poorly designed and constructed foundations that show cracking and fractures even before the buyer signs up the paperwork. These are soils that should have never been covered with those houses but the destruction continues in order to provide the "American Dream" of owning a house outside town in the "country" to everyone. The problem is that city dwellers are not familiar with the problems of living in the countryside such as having to keep the soils around the house foundation moist even in dry conditions to prevent shrinking and swelling with extreme changes in soil moisture regimes.

16th February 2008, 07:47 PM	#51
Ekka Admin - Dip Arb & Hort & Seldom Wrong Join Date: Jan 2007 Location: Brisbane Posts: 9,792	Re: Soil subsidence and trees I remember back in Adelaide (notorious for active clay soils) there was a double lane road going past K-Mart near Parafield Gardens area. It was wavey and you'd get that feeling in your stomach when driving over these waves. So, finally the roads dept decides to rip it up and fix it. Every day I travelled this road, for years. So I watched carefully. The ripped it up and excavated a little, new rocks/road base etc and rolled the living crap out of it. They were meticulous and finally went down the tarmac and it was open again. It drove like ice, beautiful. Then after a few months it was bumpy. About a year later the undulations were back. After 2 years you'd swear nothing was ever done and it was just as bad as in the first place. Go figure that out, weird, the soil was mighty unstable. There were no trees about either. They recorded in some test in Adelaide up to 75mm of soil movement up and down throughout the year. Obviously this one was a lot worse. __________________ TAS Training & Assessment Services\| Arb and Hort Training available here Free Online Tree Value Calculator by TreeWorld Free Online TPZ and SRZ AS4970-2009 Calculator by TreeWorld Free Online Tree Surface Area and Tree Volume Calculator by TreeWorld Free Tree and Green Industry Deep Link Directory ... Yes, I also SEO (Optimize) and build websites that fly high in Google Qualified Brisbane Tree Lopping \| Stump Grinding Brisbane Brisbane - Gold Coast Consulting Arborist, Tree and Arborist Reports \| Project Arborist

22nd June 2008, 09:31 AM	#53
Sean Freeman PDF King & Arborist Extrodinaire Join Date: Feb 2007 Location: Townsville Nth Queensland & Gold Coast Sth Queensland Posts: 2,149	Re: Soil subsidence and trees Sometimes you feel like its one step forward and five back! This kind of rubbish makes me almost give up on people it really does....200yr old trees with probably twice that left in them (maybe) removed. No there's no engineering solution.....rubbish there's always an engineering solution just comes down to cost and the will to do it. There was a list of steps that Veteran trees should be subjected to before any consideration of any kind of damaging works is made...of course I can't find the darn thing now...but it summarises basically everything I have written on this topic before.... 1) Review geotech data 2) Review foundation specs for buildings affected 3) Examine foundations and sub soil 4) Undertake comprehensive geotech assessment of the building and the sub soil 5) Establish if stability changes or cyclic or progressive 6) Install level monitoring/crack monitors 7) ID the species of the roots (if any) effecting the subsoil around foundations 8) Assess suitability of moisture barrier around building foundation etc.... Now these steps may have been followed or some of them I don't know...though I doubt it. There is literally heaps of things to be done long before anyone even considers picking up a saw, its too easy to simplistically point to the big old trees and say yes they are causing this foundation problem. When the trees under suspiscion are veterans, and of significance to the local (or wider) community the burden of proof should be on those wanting to damage the trees, since it is not a simple causal relationship that has not been proven incorrect. __________________ Sean Trees are poems that earth writes upon the sky, We fell them down and turn them into paper, That we may record our emptiness. - Kahlil Gibran http://wanderingarborist.blogspot.com/ http://veterantreegroup.blogspot.com/ http://www.youtube.com/user/VeteranTreeGroup

22nd June 2008, 05:16 PM	#54
Ekka Admin - Dip Arb & Hort & Seldom Wrong Join Date: Jan 2007 Location: Brisbane Posts: 9,792	Re: Soil subsidence and trees 25 years ago makes it built 1983 So in 1983 what were the specs? Did they have to reinforce for subsidence and trees? Here the foundation regs for trees came out 1995. The other issue is the TPZ for development site tree protection simply is not the same as the subsidence perimeter. You might for example build 5m away from a large tree however the area for soil subsidence influence might be 10m etc. And as you know here they use tree ht as factor. If tree is 100' tall then it must be 100' away ... or top it to the right distance. This is where we are in 2008 with trees and buildings, yet, for every soil engineer, structural engineer and arborist there perhaps 300 lawyers coming out of Uni. Like the hoop pine I had to report on, which I never did. It was the anti-subsidence tree but earmarked for removal. When all else fails blame the tree. The good thing about many Queensland homes is they were built on stilts and out of wood. So they had movement but never cracked. The ole double brick is the worst, brick veneer next best and wood the best for reactive soils. Do you remember the Kansai International Airport? I watched a documentary on it, amazing engineering. They drilled and drilled but couldn't find rock so they came up with a great foundation idea. They thought it would settle some 15m in 50 years but it settled around 11m in 5 years. To overcome they had alarms set to the building with huge jacks and would literally go around jacking it up. No shit, first floor would become ground floor, the entire building was modular with doorways being like slots and a fake ceiling. Here's a ppt on it http://ecow.engr.wisc.edu/cgi-bin/ge...nalairport.ppt Anyway, morale of the story is there were no trees to blame it on. __________________ TAS Training & Assessment Services\| Arb and Hort Training available here Free Online Tree Value Calculator by TreeWorld Free Online TPZ and SRZ AS4970-2009 Calculator by TreeWorld Free Online Tree Surface Area and Tree Volume Calculator by TreeWorld Free Tree and Green Industry Deep Link Directory ... Yes, I also SEO (Optimize) and build websites that fly high in Google Qualified Brisbane Tree Lopping \| Stump Grinding Brisbane Brisbane - Gold Coast Consulting Arborist, Tree and Arborist Reports \| Project Arborist

23rd June 2008, 04:48 AM	#55
Oldtimer Semi-mature vigorous tree Join Date: Jan 2007 Location: Austin TX Posts: 105	Re: Soil subsidence and trees This is kind of funny. The reason why the houses were built there in the first place was because of the beautiful trees that "naturaly" were growing there, So, now trees are a "nuisance" to the owners and it is time to kill them-trees. I hope their Electric utility bill triple or more now that they will not have the trees nearby to cool off their stupid-sinking-in-the-ground-houses! Hopefully their land will become a desert and blow away in the wind. Some land developers and home owners just do not have a sense!

23rd June 2008, 08:36 AM	#56
Ekka Admin - Dip Arb & Hort & Seldom Wrong Join Date: Jan 2007 Location: Brisbane Posts: 9,792	Re: Soil subsidence and trees You'd think they'd have taken more consideration for 175 year old trees, a subterranean retaining wall/root barrier would have done the trick. __________________ TAS Training & Assessment Services\| Arb and Hort Training available here Free Online Tree Value Calculator by TreeWorld Free Online TPZ and SRZ AS4970-2009 Calculator by TreeWorld Free Online Tree Surface Area and Tree Volume Calculator by TreeWorld Free Tree and Green Industry Deep Link Directory ... Yes, I also SEO (Optimize) and build websites that fly high in Google Qualified Brisbane Tree Lopping \| Stump Grinding Brisbane Brisbane - Gold Coast Consulting Arborist, Tree and Arborist Reports \| Project Arborist

3rd July 2008, 11:30 PM	#58
Ekka Admin - Dip Arb & Hort & Seldom Wrong Join Date: Jan 2007 Location: Brisbane Posts: 9,792	Re: Soil subsidence and trees We got those stupid fire ants up here too, came in soil. __________________ TAS Training & Assessment Services\| Arb and Hort Training available here Free Online Tree Value Calculator by TreeWorld Free Online TPZ and SRZ AS4970-2009 Calculator by TreeWorld Free Online Tree Surface Area and Tree Volume Calculator by TreeWorld Free Tree and Green Industry Deep Link Directory ... Yes, I also SEO (Optimize) and build websites that fly high in Google Qualified Brisbane Tree Lopping \| Stump Grinding Brisbane Brisbane - Gold Coast Consulting Arborist, Tree and Arborist Reports \| Project Arborist

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