You are currently browsing the tag archive for the ‘building foundations’ tag.

This Camphor Laurel is a very big tree. The 3rd floor of the house is visible in the photo. Although many people don’t like this species of tree because they say it wrecks house foundations, this one stands no more than 2 metres from the house without any ill effect. It can be baking at the front of the house, yet a cool oasis in the back garden because of this tree. The owners love it.

I am always serious on this site, so to lighten things up, here is a paragraph about the value of trees from the book, Villa Incognito by Tom Robbins.  Well, he made me laugh despite his penetrating insight.

“….why would they fell trees, but leave men standing?  Trees are a damn sight more useful than people & everything in the world knows that except people.”  Maybe he had a point.  Trees do generate oxygen; men just breathe it up, stink it up & generally misuse it.  Trees hold the soil in place, men are constantly displacing it.  Trees provide shelter & protection to countless species, men threaten the existence of those species.  When in sufficient number, trees regulate atmospheric temperatures, men endanger the planet by knocking those regulations askew.  You can’t rest in the shade of a human, not even a roly-poly one. And isn’t it refreshing that trees can undergo periodic change without having a nervous breakdown over it?  And which has more dignity – the calmer spiritual presence – a tree or typical Homo sapiens?  Best of all, perhaps, what Maple or Cypress ever tried to sell you something you didn’t want?  Trite?  Probably, but so what?

Here ends the wisdom of Tom Robbins.

Advertisements

Marrickville Council is currently building a large swale on Thornley Street, Marrickville South.  It is located at the bottom of the series of parks that descend  the hill at The Warren.  It’s a big swale & I think it is going to be very beautiful. There has done some fabulous landscaping done around here over the last few years.  It’s also going to be great for local wildlife & I bet the frogs move in within days.

Building the swale in Thornley Street

A different type of swale, which is amazingly simple as well as very good-looking is happening in Portland USA.  I continue to be very impressed with this city’s approach to public trees & other green infrastructure.  The picture below has come directly from http://friendsoftrees.org/blog/2010/03/04/next-generation-street-trees-live-in-swales/

brilliant swales in Portland USA

The Cumberland Courier reported on a massive swale built in Cheltenham by Hornsby Council.  It’s well worth a look.   http://cumberland-courier.whereilive.com.au/news/story/stormwater-treatment-system-takes-root/

Moving away from swales to planter boxes with a difference, I found something truly fabulous happening in Hatertseweg, Netherlands.  The council had built a huge underground planter box that was going to ensure no tree messed with the foundations of a building ever again.  Great stuff.  http://jim-labbe.travellerspoint.com/21/

The Cambridge Street Stanmore Lemon Scented Gum tree is going to be chopped down soon.  I feel very sad about this.  During the Council meeting to decide the fate of this tree, the people who wanted this tree removed spoke about a large branch that fell on the street needing 2 people to carry it away.  The danger the tree posed from falling branches would have been one of the major factors why their request was granted.

Gum street tree in Petersham - 2 Currawongs have a nest in this tree

Gums trees do drop dead branches as a normal feature of their species.  Unfortunately, I think this is the reason why Marrickville Council appears not to not regard Eucalypts favourably.  Then include the fact that they grow tall & have a significant canopy.  In comparison to the usual street trees Council plants, Eucalypts are an anomaly.  I would guess the Gums are left over from the 1970s & before.

Suburbs like Petersham which have a lot of Eucalypts as street trees look fabulous as a result.  Everyone I have spoken to in this area always mentions the trees, most saying they were a major reason why they chose to buy in Petersham.  However, the Cambridge Street issue is likely to repeat itself for two reasons unless these are managed.

Firstly, building movement that causes cracking.  The Inner West is mostly clay soils & when there is drought (we have had a long one which is still continuing) the clay soils shrink. This results in movement of buildings & cracks to the walls, porches & paths, especially as most of the housing is 100 years old & the mortar used then was of very poor quality.

Roots of mature trees would have stopped growing years, perhaps decades ago. Often the tree has nothing to do with movement.  Arborists constantly have differing opinions about the impact of tree roots on house foundations.  Personally, I think it is too easy to blame the tree.

This Gum street tree in Brighton St Petersham deserves a medal for surviving pruning by Energy Australia for power lines

Even buildings that do not have a street tree out front can suffer from movement & cracking, especially during drought.  If your property is built on clay soil, removing most or all the trees on or around your property is unlikely to prevent further house movement.  It is a fact of life in the Inner West.

To minimize cracking to your house during drought, you need to water thoroughly along the exterior walls on a regular basis.  If you keep the soil moist, the clay will not shrink & your foundations are less likely to move.  Many people have concreted their yards, so they will definitely have house movement & cracking, drought or no drought.  If you already have cracking, you can assist by watering around the building to get the moisture back into the soil.  Our front door, which had started sticking, returned to normal 2 months after I recommenced watering our front garden.  I have written more fully about clay soils in the following post –

https://savingourtrees.wordpress.com/2009/12/11/11th-december-09-much-ado-about-clay-soils/

Managing dry clay soils does take time & patience.

Secondly, Eucalypts develop dead branches, which they shed as a normal feature of their development.  This does not make the species dangerous.  The process of the branch dying off until it eventually drops is not a quick one.  I have been watching trees with dead branches for 12 months now.  (It’s been one of my ‘must do posts’ which hasn’t happened until now.)  However, Gums are called ‘widow makers’ for a reason. A falling branch can kill a person if they drop on their head, but then again, so can most things that drop from a height.  I was young when I first heard the term ‘widow maker’ & I remember being told the following with much laughter:

The tree branch is dying over many months, sometimes years.  The wife asks the husband to do something about it.  Time moves on.  She nags & nags, but he watches footy & says he will prune the branch later.  Then, one day when he is mowing or something, the dirty big branch falls on his head & the wife is left a widow. The moral of the story is that men should do what their wife asks when she asks it to be done, husbands are lazy & her nagging is warranted.

Maybe you had to be there & times have changed.  The story made a big impact on me because ever since I have a keen eye to notice these branches.

This tree cnr Illawarra & Addison Rds has multiple dead branches. 3 other Gums further down towards Marrickville Rd also have dead branches

Whether or not Council should be responsible for checking trees for dying branches is not something I have an opinion about.  However, I do think we see the street trees in our neighbourhood almost daily & if we notice a tree branch is dying, a quick call or e-mail to Council should have the branch pruned before it becomes a problem & drops.

If we leave it until the branch drops, Council is likely to say the tree is dangerous & needs to be removed.  Then the community suffers another loss of a tree & eventually we lose all remaining Eucalypts & other tall trees.  Our suburbs suffer as a result because we lose the beauty that tall trees offer.  We also lose out on property values because great street trees have a surprising positive impact on local property values.

The street trees near our homes, especially the large ones, remove pollution & particulate matter which causes breathing problems.  They collect CO2 & emit oxygen making the air cleaner & cooler.  They lower temperature which helps lower our power bills, they slow down traffic, make the footpaths safer for pedestrians & generally make people feel happier.  I have written more about the value of trees in the page 100 Tree Facts, which can be located on the left hand column of this site near the top.

Lastly, if Sydney’s North Shore can have hundreds of thousands of Eucalypts as street trees, why can’t Marrickville LGA?  Let’s look after & keep the ones we have left.  They are necessary for our wildlife.

What concerns me about the removal of  street trees when they have been accused of causing damage to property is the following:

  1. We have just experienced a long & protracted drought & more than 3/4s of NSW is still regarded as drought-affected.  The long-range weather forecasters say we have entered into another phase of drought. The Inner West has been affected, as has the whole of the Sydney metropolitan region.  This drought has resulted in severe water restrictions & this has affected our soils to a great degree.  Trees are stressed & quite a few have died within our local LGA.  Many of the saplings Council plants do not survive the summer because they are not watered.  This must result in significant financial loss to Council.
  2. Even though we had quite a bit of rain over winter, we are still on water restrictions.  The park trees were able to capture much of the water when it rained, but our street trees have only a slight chance at getting a proper drink.  Most of the street trees in our LGA have been given very little ability to capture rain water or storm water run-off.  Most have a small opening left open amidst the cement or

    Newtown street tree

    bitumen. I have only seen 4-5 street trees planted in cement where I feel they have been given adequate soil space around them to give them a fighting chance to capture rainwater.  Two were in a back street of Newtown & I doubt Council did this, as the kerb had been removed.  Both these trees had a lot of soil around their trunk.  The other example is new plantings bordered by raised brickwork on Unwins Bridge Road Tempe.  I think it would be wonderful if all our street trees that are in cemented areas could be planted in this way.  I would also very much like to see Council give funding for the watering of young street trees as they do in other Councils.

  3. Much of the Inner West is built on clay soils.  Clay soils are quite volatile as they shrink when they do not get sufficient water & expand when there is too much water.  Both these extremes affect the foundations of buildings & footpaths.  The term Seasonal Fluctuations describes the normal variations of the moisture content of clay soils through the seasons.  When clay soil gets a lot of water it is called Field Capacity.  When the soil is dry due to evaporation, heat  & lack of rain during drought it is called Desiccated & suffering from Soil Moisture Deficit.  If a drought is lengthy & the soil does not return to Field Capacity after some rain & then enters into another dry period, it is called Persistent or Permanent Moisture Deficit.  This is likely to have already occurred in the Inner West or will do during the next period of drought in which we are now entering.
  4. Soil movements cause what is termed Subsistence & Heave.  With Subsistence, the soil moves downwards.  With Heave, there is an upwards or lateral move of building foundations or footpaths.  While the clay soils go through Seasonal Fluctuations foundations of buildings don’t move much, though that depends on how much clay soil is directly under the foundations.  When the clay soil suffers from Persistent Moisture Deficit, foundations of buildings move & walls start to show cracks, paint peels & doors & windows are suddenly off balance.  Just last week our front door over night became hard to open & stiff on its swing.  It is recommended that you don’t fill in the cracks or shave wood off door or window surrounds when the ground is dry, but wait until the soils have returned to normal moisture content before doing repairs.  Most times the doors & windows will realign & the cracks will come closer together though paint work will need repairing.  If you do fill cracks while the soil is dry, the space will not be available for the building to move back into place & new cracks will appear, generally on the other side of the building.
  5. The experts suggest occasional watering of the exterior of the house as this will help keep the clay soil moist so that your foundations don’t move during a drought.  In my case, I have been keeping the water up to the back garden, but to save water, I have left the front garden manage as best it can.  Here is the reason why our front door has moved. Also, it is our hallway & the front room that are suffering the cracks & peeling paint.
  6. My research has shown that trees can increase the seasonal movements of clay soil, however, engineers also stress there are too many factors to consider before one blames the presence of a tree for causing the damage.  One of the problems is, if a mature tree is removed, this has a major impact on clay soil moisture & the property can actually sustain more damage as the soil fills with water & starts a process of Heave.  It is hard to stop Heave because there is no longer a tree to be taking up the excess water.  Because it is so difficult to categorically say that tree roots cause damage even if the roots do go towards & under the house, many engineers recommend using water to restore the water levels to clay soils rather than removing the tree.  I have read that a tree is not able to lift a house because of the weight of the house. A footpath is a different story.

Trees ... we need them

There are things we can do to minimize or prevent further cracking or movement of buildings which do not involve removing trees.  According to eminent scientists, we have entered a dangerous period of existence with CO2 levels actually threatening life on this planet.  All agree on the supreme value of trees.

Just today in Copenhagen, the Food & Agriculture Organisation of the United Nations & Brazil’s National Institute for Space Research signed an agreement to work together in the field of emissions measuring and reporting by monitoring forests & calculating CO2 sequestration.  Essentially they are going to map & monitor the green canopy of forests of the world.  This clearly demonstrates the value of trees in dealing with climate change.  We should only be removing them after all options have been exhausted.

Archives

Categories

© Copyright

Using and copying text and photographs is not permitted without my permission.

Blog Stats

  • 619,976 hits
Advertisements
%d bloggers like this: