Seeking advise on house cracks

That's a good point. I guess because all of this is new to me; should the builder have acquired an indenpendent report? Or is it well within their right to just go back to the same people?

With regards to the trees (gumtrees to be more specific), these were there on the reserve before the house was built.

From your opening post, the above comment from the builder was noticeable given that they had already apportioned blame for the cracking to the landscaping. They shouldn't be making early assumptions like this.



The BCA requirement calls for a 1:20 minimum fall over the first 1 metre from the building edge. I am not aware of "a minimum fall of 1:50 over the first 1.5m from the building edge" also being acceptable but if it is, then someone is sure to clarify it.


Take it from me...a plumber's compliance certificate means diddly. The only guarantee that the drainage is compliant and sound is to have it investigated.

When building, it is important to take lots of photos, did you do this? Photos will show the builders attention to site drainage during the build and whether the site was graded away from the slab. If you do have photos, do they show water pooling next to the slab during construction or other areas of concern?

Also, because you are almost certain to have slotted gutters, do they overflow through the slots during heavy rain? New home stormwater drainage is often not compliant in Victoria and overflowing slotted gutters pooling water next to house slabs is common.

I could not see any reference to the age of the house in your posts. It is important to include this information. Also, how long after you moved in was the landscaping done? It is difficult to assess an issue when no time frames are given.

Hi SaveH2O thanks for chiming in.

Regarding the builder's comment, I did try seeking clarification as to why they jumped on the landscaping side of things and (seemingly) ignored to comment on say the plumbing side of things.

But as someone else had already mentioned, it seems it is not uncommon for the builder to apportion blame to the landscapers.

I don't really have anything else to add to that as I am really not sure what else I can do at this stage with that. Ideally I would have liked them to facilitate the plumbers to come and investigate. But what we like to have doesn't always equate to what we will get.

I wont comment on BCA requirements as I have absolutely zero clue about it. I can understand somethings but a lot of this does go over my head.

As for plumber's compliance, I did hint that to the builders. But they pretty much said if the plumber I get in shows that the plumbing work is faulty etc they will be more than happy to get the original plumber back to fix it up.

As for photos of the place, I will say I have no photos that can be used as evidence. Hindsight is always good but when I bought this place, I was learning the ropes and missed a lot of the 'should have done' items.

As for overflowing gutters at this stage no. There have been signs where water has flowed back into the ceiling/roof?? when there have been heavy downpours.


The house was finished late November 2008. The Landscaping was pretty much done when we moved in. Nothing else has been done since. Apologies for not including this later but it is my intention to provide any details required here that will help but I just didn't want to go unnecessarily overboard.

Thanks again for taking the time to read and prompt me.

Yes, this is standard fare.

The pipes will be easy to check. I think it was insider who posted on another thread that leaking/damaged pipes were responsible for nearly half of the slab heave cases that he has investigated.


Water from overflowing gutters won't over-top the fascia and flow back into the house unless there is non compliance. It is a concern that you have had water flowing back into the house during heavy rain but you first state that you haven't had overflowing gutters and so I am assuming that there is a typo somewhere in one of the sentences.

I was actually asking whether you had slotted gutters, whether they overflowed during heavy rain and whether the overflow resulted in pooling around the slab. People wrongly accept slotted gutters overflowing during heavy rain that is nevertheless below the 1:20 ARI intensity that roof drainage compliance is based on. If overflowing gutters cause pooling next to the slab, the pooling can easily contribute to heave but this is often overlooked as a cause.


Ok...6 1/2 years. That certainly brings the landscaping into contention. Having the pipes examined is obviously the first step.

A friend of mine had the front of his big dollar house drop and an independent engineer found that the fill didn't extend out far enough from the slab. I forget the exact details but I can ask him and post the findings if you are interested given that you are on a P site. The builder's engineers who did tests failed to find the true cause. His house is built on a slope.

Good luck.

Interesting. Seems like getting a plumber in is definitely the right thing to do. Or if nothing else, most definitely worth doing.



I just realised how silly it was for me to say the gutters didn't overflow and yet there were times when our ceiling presented signs of water marks. I apologise for that. So yes, based on the fact that I've seen water marks in various spots of the living room, the gutters can overflow. However I am not sure if they are slotted gutters. I am trying to google what slotted gutters look like.

Having said that I've not seen pooling on the ground....but then again I will say that I hadn't been on a look out.[/quote]


One other question I've got is what is defined as landscaping in this context. With my ignorant mind, I've only ever associated landscaping with the types of plants planted, look of the garden. I never though drainage was part of landscaping.

I've been getting some quotes from plumbers since getting the report. But I think I am wary of getting the 'wrong' plumbers. I would like to engage someone who will do a good job from the get go. Otherwise I'd end up wasting more time (and potentially more money).

If you or anyone else - Insider perhaps?? - could recommend a reputable party I'd appreciate that very much.



Thanks for this. I wouldn't mind having a look and I'd be interested to even get the contact details of the independent engineer to see if they service my area - if I should need to go down approach. Would you know if the builders have a responsibility to engage an independent engineer when addressing these things?

Once again thank you so much for your time and input. I really appreciate it and it's helping me learn as I go too.

Being a double storey on moderately reactive soil the chance of heave are reduced but not impossible.How close are the gum trees to your house?
You need a geotechnical engineer to
1 drill boreholes and take samples
2 confirm the original classification is correct (may require tube sample for shrink/swell test) and geology
3 take floor levels
4 engage a forensic plumber to confirm condition of the plumbing
5 make recommendations in regards to the cause and solution.

My first suspicion would be the trees.Hopefully the trees were taken into account originally with the "p" classification.Clayton generally has more settlement issue than heave but the best way to really confirm this is to look at the soil under your slab.
A good geotechnical investigation will set you back $1000 to $2000.
If you want the name of some geotech companies send me a PM

Slotted gutters are gutters than when you look at them from the outside you see slots just below the top edge. The slots allow water to come out of them when the downpipes are not coping with draining away the water in them. The water comes out of the slot and falls to the ground below. That is not ideal but better than water flowing into your ceilings. Better performing down pipes are the best option either by being larger diameter or just more of them draining water into the storm water pipes and away from the slab.

Here is an image of the trees relative to house. It's right next to our fence.

http://screencast.com/t/JgDDlRohSivV

Just to clarify Insider, the geotech. engineer is pretty much what Intrax is? Just trying to get my head around it all.

$1000-$2000 gulp...but if it has to be done it has to be done.

I will PM for the companies. Thanks again Insider.

Thanks goody59. That was extremely helpful. I do not have slotted gutters as I do not see any water pouring over the gutters and unto the garden pavers etc.

After seeing the photo, I agree with insider as the trees being the most likely culprits. Large gum trees are inappropriate in an urban environment where there is a low % area of permeable surface.

People tend to think that tree roots are the primary cause of house foundation issues but the roots don't need to reach the house to cause damage, the damage is usually caused by a natural phenomena known as matric suction. If you enter matric in the forum's search facility, you will come up with some of my posts where matric suction has been discussed.

There have been some landmark court decisions the past few years where matric suction has been determined through geotechnical evidence to have caused property damage. I may have linked some of those cases in my Homeone posts...otherwise I will have them on file somewhere.

Thanks for that. I guess it's safe to say that it'd be best that I get:
1. A forensic plumber in
2. An independent geotechnical engineer in

I've also just requested for the builder to provide me with copies of the original geotechnical report and structural engineer report.

Just a question though, as the trees are council owned, what happens there if the trees are indeed the cause of the heave? I've previously contacted the council to have them remove the tree as it overhangs on my gutters but they've hardly budge. So I am just wondering what happens in this instance?

I also find it interesting though that the heave is occurring on the complete opposite side of where the trees are. I am not saying that the heave is not happening elsewhere just that the area that is currently being affected the most furthest away from the trees. (see area in blue in the image)

http://screencast.com/t/oaEakc5ZnM




Thanks again for everything.

The trees won't be the cause of the heave.It is tricky sometimes when looking at floor levels alone to determine whether there is heave or settlement or both.The area away from the trees may in fact not be heaving but is relative level and the area near the trees could be lower giving the appearance that the none tree side is heaving.
This is why it is essential to drill test holes to confirm this with moisture samples.
Moving the zero point for the floor levels can give you a completely different understanding of cause of the damage so be careful.
Was your slab designed with piers or a root barrier to counter the trees effect ?

I would be interested to see what the independent soil test classifies the site as.

Is your neighbour having any issues?

I will be following this closely.

Ok. It appears that I need to two key terms that I need to be mindful of - heave and settlement. Each play a part in house movement.

Could you elaborate on what you mean by "moving the zero point"? And how can I or what should I be looking / asking for when the geotech. engineer comes on site to ensure that they are doing the 'right' thing?

Thank you Insider.

Alright for those interested in how this is going:

1. I'm getting quotes for a forensic plumber.
2. Depending on the results, I will forward the findings to my builder.
3. Depending on the results there I might go get my own geotech. engineer.

For those in the know, do you think I should use my home insurance in the event that the builders (rightly or wrongly so) don't come to the party?

The post below had links to two such topics but both links are no longer functional.

viewtopic.php?p=909577#p909577

One link was a Knox Leader news article about local residents battles with the Knox council over council planted gum trees and the councils refusal to accept that the trees were the cause of damage to adjacent houses. After the residents had a report from a geotechnical engineer that the damage to the houses was indeed caused by the trees through the process of matric suction, the council changed its mind before matters proceeded to court. The Knox Leader will have archive copies.

The second link concerned Thomson Vs the City of Unley in South Australia and I still have this court judgement on file. I have pasted it further below.

There was also a landmark case in the City of Goulburn from memory a short time before the Unley case but I can't find it. There have been several similar cases since.


Environment, Resources and Development Court of South Australia

DISCLAIMER - Every effort has been made to comply with suppression orders or statutory provisions prohibiting publication that may apply to this judgment. The onus remains on any person using material in the judgment to ensure that the intended use of that material does not breach any such order or provision. Further enquiries may be directed to the Registry of the Court in which it was generated.

THOMPSON v CITY OF UNLEY

[2008] SAERDC 62

Judgment of Commissioner Mosel

18 September 2008

ENVIRONMENT AND PLANNING - ENVIRONMENTAL PLANNING - DEVELOPMENT CONTROL

Development application to remove a significant tree (Eucalyptus camaldulensis) - Residential A560 Zone - consent refused by the Council - the tree is a structurally sound and healthy specimen about 40 years old - whether the roots of the tree are the cause of soil dessication and thus structural damage to the dwelling and whether the remedial options are reasonable are the two principle issues - damage found to be "substantial" - on the balance of probabilities the tree is found to be the major contributing factor - all remedial treatments canvassed in the proceedings found to be either ineffective or unreasonable in the circumstances - appeal allowed - consent granted.

Development Act 1993; Development Regulations 1993, referred to.

Summer v City of Unley [2002] SAERDC 113, considered.

THOMPSON v CITY OF UNLEY

[2008] SAERDC 62

THE COURT DELIVERED THE FOLLOWING JUDGMENT:

1 The appellant, Mr Anthony Thompson, owns the land at 42 Northgate Street, Unley Park (“the subject land”). This appeal is against the decision of the City of Unley (“the Council”) to refuse Development Plan Consent to the appellant’s application to remove a significant tree from the front yard of the land.

2 The tree sought to be removed is situated near the southern wall of the dwelling on the subject land. The appellant contends that the tree is causing structural damage to that part of the dwelling. He further contends that the removal of the tree is the most appropriate remedy to avoid further damage occurring as the tree grows and to restore the dwelling to a satisfactory state. It can be reasonably inferred from the evidence that the stabilisation of the superstructure of the dwelling would provide the confidence needed to embark on certain additions and renovations.

3 Some relevant information about the proposal is set out hereunder:

Subject land address:


Lot 141 in Filed Plan 11444 (Certificate of Title 5127/349

Proposed Development:


Removal of a significant tree (River Red Gum: Eucalyptus camaldulensis)

Development Application No.


090/1062/2007/C2

Existing use:


Residential (detached dwelling)

Relevant Development Plan:


Unley (City) 11 May 2006

Relevant Zone:


Residential A560 (“the Zone”)

Date of Decision:


21 January 2008

4 In these proceedings the Court heard evidence from the following:

Mr L Thompson – father of the appellant who presently resides on the subject land;
Dr P Mitchell – Geotechnical engineer (Statement: Exhibit A1);
Mr R Liney – Consulting engineer (Statement: Exhibit A2);
Mr T John – Consulting engineer (Statement: Exhibit R2); and
Mr K Knight – Consulting arborist (Statement: Exhibit R3)

The Existing Dwelling and the Tree to be Removed

5 The subject land is occupied by a solid masonry dwelling. The original part of the dwelling is about 100 years old. The main bedroom and entry hall were added forward of the original dwelling in the 1920s. It is this part of the dwelling that the appellant says has been structurally damaged by the tree.

6 Between the dwelling and the front boundary of the subject land is a large garden. Within the garden is a large lawn, garden beds near the front (southern) and side (eastern) walls of the dwelling and a number of trees and shrubs.

7 The tree sought to be removed is identified and described by Mr Knight in his statement of evidence (Exhibit R3). It is a River Red Gum (Eucalyptus camaldulensis) which is about 15 metres tall and has a crown of about 7.6 metres. It is situated about 6.1 metres from the southern wall of the dwelling. Nothing turns on the differences between the measurements taken by Mr Knight and those recorded in Mr Whitehill’s letter to Mrs Thompson dated 27 October 2007 (Exhibit R1).

8 It is common ground that the subject tree is a “significant tree” within the meaning of that term in Regulation 6A, Development Regulations 1993.

9 Mr Knight also recorded in his statement other species of trees near the dwelling which he opines are either associated with structural damage to buildings or have the potential to affect soil moisture and, in turn, building stability. They are as follows:

Weeping bottlebrush (Callistanon vininalis) – 10.4 metres tall, 11 metres diameter, 1.6 metres diameter trunk situated 1.8 metres from the corner of the verandah, 5.9 metres from the southern wall;
Monterey cypress hedge (Cupressus macrocarpa) – extending along the western boundary 5 metres from the western wall of the residence;
two medium size trees;
Wild Plum (Pronus amygdalo “persica”)
Umbrella Tree (Schefflera actinophylla)

10 The subject tree is described by Mr Knight as healthy and structurally sound. In oral evidence he said “the tree is about 40 years old and has a life span of 100 years or more”. Mr Knight said the tree could be expected to reach a height of 20-30 metres and a diameter of the same magnitude.

The Damage

11 That the front rooms of the dwelling have suffered cracking in the walls both internally and externally is not contested by the respondent. The Court observed cracks in the entry hall, main bedroom and living room (the latter room as I understand the evidence, is part of the original dwelling). The cracks inside the dwelling are obvious and on my observation are numerous, active and could not be regarded as minor or cosmetic. Neither are the cracks observed externally (some of which have been filled in with mortar).

12 In order to properly apply the relevant principles set out below it is necessary to have appropriate regard to the expert evidence as to the nature and extent of cracking and distortion. Dr Mitchell, in Exhibit A1, was very broad in his description and, in this respect, was not particularly helpful. However, in oral evidence he explained the relationship between the cracks and the distortion of the footings along the southern wall of the house – a consequence he said of soil shrinkage following a loss of moisture. The front portion of the building, he said, is rotating in a southerly direction with a pronounced distortion and subsidence near the subject tree. Since his first inspection some months ago, the cracks have opened further.

13 Mr Liney’s evidence about the damage to the dwelling was consistent with that of Dr Mitchell. He opined that some cracks were 30mm in width and that the floor had subsided much the same distance. He said in reference to AS 2870 (Residential Slabs and Footings – Construction Code), the dwelling “would be considered to have significant Category 3 damage to the walls”. He confirmed Dr Mitchell’s observations that the cracks have opened further in recent months.

14 Mr Liney also observed that there was little or no cracking in the south eastern part of the original dwelling noting, in that aspect of his evidence, that it was further from the tree and most probably built on inferior footings.

15 Mr John in Exhibit R2, described the cracking as “noticeable”. In oral evidence he was reluctant to place the cracks within a classification under AS 2870 but if he “had to put a number to it” it would be a Category 2. He opined that the movement in the walls are in defined locations and more in the nature of joint movement. He could not conclude, on his analysis, that the damage was substantial.

The Relevant Provisions of the Development Plan

16 Principle 179 speaks most directly to the substance of this appeal:

179 Significant trees should be preserved and tree-damaging activity should not be undertaken unless:

(a) in the case of tree removal;

(i) the tree is diseased and its life expectancy is short; or

(ii) the tree represents an unacceptable risk to public or private safety; or

(iii) the tree is shown to be causing or threatening to cause substantial damage to a substantial building or structure of value and all other reasonable remedial treatments and measures have been determined to be ineffective; or

(iv) it is demonstrated that reasonable alternative development options and design solutions in accord with Council-wide, Zone and Area provisions have been considered to minimise inappropriate tree-damaging activity occurring.

…

17 It is common ground between the parties that item (iii) of Principle 179(a) is most relevant. There is no evidence to suggest that the tree is anything other than a healthy tree or that it is a risk to personal safety.

18 Objective 56 and Principle 177 are also for consideration:

Objective 56: The preservation of significant trees in The City of Unley which provide important aesthetic and environmental benefit.

Trees are a highly valued part of the Metropolitan Adelaide and Unley environment and are important for a number of reasons including high aesthetic value, preservation of bio-diversity, provision of habitat for fauna, and preservation of original and remnant vegetation.

While indiscriminate and inappropriate significant tree removal should be generally prevented, the preservation of significant trees should occur in balance with achieving appropriate development.

177 Where a significant tree or significant tree grouping:

(a) makes an important contribution to the character or amenity of the local area; or

(b) forms a notable visual element to the landscape of the local area; or

(c) contributes to habitat value of an area individually, or provides links to other vegetation which forms a wildlife corridor;

development should preserve these attributes.

19 The weight to be applied to the foregoing provisions might also be determined by certain provisions for the Residential A560 Zone: Summer v City of Unley [2002] SAERDC 113. Objective 2 for the Zone is in the following terms:

Objective 2: Preservation of the existing residential character, provided by the preponderance of detached dwellings, uniform set-backs and a high standard of landscaping.

20 The reference in this objective to “a high standard of landscaping” is reinforced by an aspect of the Desired Character as follows:

Streetscape

The mature age and generous allotment sizes of various subdivisions within the Residential A560 Zone has ensured a preponderance of mature trees comprising remnant native vegetation and mature exotic species. Street reserve planting has generally complemented the species in private gardens. This attractive living environment where buildings are enclosed by the surrounding landscape should be maintained and enhanced.

Assessment

21 The Development Plan seeks, in the Zone, to preserve attractive living environments by, among other things, maintaining and enhancing private gardens and street trees. Insofar as a private garden has within it a significant tree (the subject land being one example), the terms of Objective 56 clearly act in support of that goal.

22 Does this mean all significant trees are to be preserved? The answer to that question is “no”. Objective 56 qualifies the type of significant trees sought to be preserved; namely those which “provide important aesthetic and environmental benefit(s)”. Principle 177, curiously worded as it is, provides particular tests to assist the determination of whether a significant tree falls within the ambit of Objective 56.

23 Whether the subject tree meets one or more of the criteria in Principle 177 and thus Objective 56 appears to me to be a threshold question to be answered before the tests of Principle 179(a)(iii) should apply. Mr Knight, a qualified and experienced arborist who appeared in the case for the Respondent, on p 7 of Exhibit R3 said in respect of part (c) of Principle 177 the following:

The tree is one of many native trees in the locality that would assist with bird and animal movements across the area. River Red Gums are one of the most biologically diverse species supporting numerous organisms.

24 Somewhat surprisingly, Mr Knight’s views in this respect were not seriously challenged by the appellant. Mr Knight is a well qualified arborist with many years of practice and experience behind him. He is not, with respect, a person who is sufficiently qualified to provide expert advice about the habitat value of the subject tree insofar as that issue is a matter for consideration in Principle 177(c). I think the same can be said for his views expressed in respect of parts (a) and (b) of that Principle.

25 Whether the subject tree meets any of the criteria in Principle 177 is an important test in the resolution of this appeal. Nevertheless, the appellant did not seriously challenge the proposition that Principle 177(c) applies. That being the case and there being no specialist or expert evidence to the contrary, I accept the subject tree meets the criteria set out in Principle 177(c).

26 The proposal to remove the subject tree must therefore be assessed against Principle 179(a)(iii). There are a number of aspects of this principle that require specific consideration. That the dwelling is “a substantial building or structure of value” is not a matter of disagreement between the parties. That is a conclusion that can be reached upon viewing the subject land and upon consideration of the evidence of Mr Thompson.

27 Thus, in determining whether the removal of the subject tree should be permitted it is necessary to decide:

(a) whether the damage to the dwelling is “substantial”;

(b) whether the tree is the cause of the damage (or threatens to cause damage); and

(c) whether the remedial treatments canvassed during the hearing are considered by the Court to be reasonable and, if so, whether they are determined to be ineffective.

Substantial damage

28 Is the damage to the dwelling “substantial”? There is a considerable measure of subjectivity necessary to decide this question. It is also a question that is to be answered without having regard to its possible cause or causes. This is a distinction that was not fully appreciated by Mr John in his evidence. He was by no means dismissive of the nature and extent of the cracking and evidence of distortion. However, it appeared to me when addressing this aspect of Principle 177(a)(iii) in oral evidence, he thought the cracks were acceptable because they are to be expected in the circumstances. To put it colloquially, it seems that he thinks the damage is “par for the course”.

29 As I have said, the cracks cannot be regarded as minor or cosmetic. They occur internally in three rooms and externally at various points along the southern wall. From my observation some would accord with Mr Liney’s measurements.

30 The position, severity and number of cracks are a consequence of the subsidence of the footings. The subsidence has been measured to be in excess of 30mm. The distortion of the footings, in my view, would be an element in the damage to the superstructure.

31 I find that taken together, the cracks and footings distortion amount to “substantial damage”.

Cause of the damage

32 There are two facts that have a bearing on the structural stability of the house that are agreed between the parties. First, the evidence from all expert engineers indicates the soil type to be a Red Brown Earth Type 5 soil classification. Using AS 2870 it would be defined as a Class H highly reactive clay site. All generally agree that a class H soil can experience ground movement of up to 70mm as the moisture in the soil changes.

33 Secondly, the expert engineers agree that the footings supporting the front portion of the house are most probably “strip footings” (about 450mm wide and 450mm deep). They also agree that footings of these dimensions would not meet present day design specifications for the soil type and conditions. I do not think there is any disagreement about the following opinion expressed by Dr Mitchell:

This footing type has been found to be unable to adequately resist the soil movements associated with a class H soil profile. As a result, wall cracking is commonly associated with this footing system on class H soils, and even more so when the effects of trees are imposed.

This is evidenced in this house by the presence of previously repaired cracks.

34 There is a third issue to which the expert engineers have expressed general agreement. It relates to the connection between trees and the stability of the superstructure of a dwelling. Dr Mitchell in his statement of evidence summarised the connection in the following terms:

Trees for their survival require water both to undertake the process of photosyntheses, and to provide nourishment to the tree, this water being drawn from the subsoil by means of their fibrous root systems. When the soil is expansive, this reduction in subsoil moisture results in a shrinkage of the soil, the footings of buildings overlying the soil profile will undergo a settlement in response to this soil shrinkage. The footing settlement can be sufficient to distort and crack structure if it is incapable of accommodating this movement.

Case examples of tree damage to structures throughout the world have been well documented. Generally, it has been found that the problem becomes adverse with younger developing trees and during periods of dry weather, when the tree demands more water that is available from rainfall. It has also been found that native Australian eucalypt trees are prone to lead to damage to houses.

35 Dr Mitchell is a highly qualified and long experienced geotechnical engineer. He specialises in that aspect of geotechnical engineering that “relates to the impact of soils and geology and other geological materials on the built environment” (Transcript p 17). During his work-life (including work overseas as a Churchill Fellow) he estimates he has examined in the order of 8000 cracked houses, 60% of which he opined were due to the effect of trees. His PhD thesis was related to the effect of trees on buildings. He has also undertaken studies to determine the zone of influence of River Red Gums in soils similar to that on the subject land.

36 Dr Mitchell (and Mr Liney) have no doubt that the subject tree is the cause of the damage to the house (Transcript p 22). The former’s conclusion is based on the proximity of the subject tree to the house, the high water requirements of the River Red Gum species, the likelihood of the soil suction gradient extending beneath the dwelling, the pattern of cracking and subsidence and the influence of the continued dry conditions in metropolitan Adelaide.

37 Mr Knight agreed that the subject tree is a species that is known as a “luxuriant water user” (Transcript p 179). Also, the likelihood of the soil suction zone of the subject tree extending under the house or to a point where moisture depletion may affect building stability was not a proposition seriously challenged by him (Transcript p 181).

38 Mr John in his statement of evidence opined that the tree “may be a contributor to the cracking now evident in the walls, and may be a contributor in the future, but not to such a degree that it can not be reasonably controlled by appropriate site and building and management practices”. He further concluded as follows:

Reasonable methods of reducing the cracking now evident have not been implemented.

It is my opinion, based on the information currently available, that the building has been performed to a quite acceptable standard over most of its life considering the type of building construction and the footings, and that the distress now evident can be addressed without the removal of the tree.

39 The principal difference between the opinions expressed by Dr Mitchell (and Mr Liney) and that of Mr John was whether the damage was primarily attributable to the subject tree (by way of soil desiccation) or whether it was due to inadequate footings design/strength and poor site management. On this question I prefer the evidence of Dr Mitchell largely because of his specialist knowledge and research on this very issue. I am reinforced in taking this course by the following. Had poor site management and inadequate footings been the primary cause of the damage they, together, would manifest in cracking in the original part of the dwelling nearest the tree which, according to Mr Liney, is constructed on bluestone footing material – a more inferior footing type. Mr Liney said that horizontal defection (Transcript p 89) or movement in the walls in that part of the original dwelling nearest the subject tree was not evident (Transcript pp 98/99).

40 There may be factors other than the subject tree at work. It is not the only cause of the damage. However, when the expert evidence is carefully considered, I have found, on the balance of probabilities, the subject tree to be the major contributing factor. The evidence also indicated that as the tree grows and matures there is a high likelihood of further instability being caused to the superstructure of the dwelling.

41 There is nothing in the relevant provisions that suggest I should regard the type of footings under the dwelling as a factor acting in support of the respondent’s case.

Remedial Treatment

42 Four means of remediation were canvassed during the course of the hearing:

(a) installation of root barriers;

(b) underpinning of the footings;

(c) installation of control joint;

(d) re-hydration of the soil.

43 The evidence in respect of (a) and (b) above appears to me to be consistent in the case of both parties. Root barriers are inordinately expensive (and unreasonable in the circumstances), are difficult to install and are prone to failure. In the same vein, the underpinning necessary to achieve stability is cost prohibitive and unreasonably disruptive to household needs and functions.

44 I have considered, at some length, the other methods canvassed. Dr Mitchell and Mr Liney opined that the installation of control joints would not be sufficient or effective. The former opines that articulation of the house will be necessary to increase wall flexibility even if the tree was removed. The prime problem he said is the inadequacy of the footings to cope with the desiccation of the soil occasioned by the removal of moisture by the subject tree. The soil desiccation will continue as the tree continues to grow and soils continue to dry. In other words, control joints are not a viable alternative to tree removal simply because it does not deal with the cause of the problem.

45 Although Mr John opined that the installation of control joints would “improve the performance of the building”, I do not think that he disagreed with the fundamental tenet of Dr Mitchell’s evidence about this method as a means of eliminating the problem. Mr John’s evidence on this point is, understandably, influenced by his views summarised earlier. That is, the cracks are not caused by the tree and are to be expected given the footings and soil types.

46 At best, the installation of control joints is a holding measure. While the major cause of soil desiccation remains and magnifies over time so will footings rotation and distortion and therefore wall cracking. Cosmetic improvements would be made with the control joints in place. However I find that it is not likely to be effective in the long term.

47 It remains now to consider re-hydration of the soil. On this point I prefer the evidence of the expert engineers to that of Mr Knight. In the end it is a geotechnical problem to be solved. Simply put, this method involves the injection of water into the soil to quite some depth. The evidence of the expert engineers indicates that the method is not cost prohibitive and could be easily installed. However, that is not the end of it. Dr Mitchell’s opinion that it would take a long time, perhaps many years, to properly re-moisturise the soil was not seriously challenged by the expert engineers. Nor was his opinion that, to be effective and to avoid over-saturating the soil, it is necessary to constantly test moisture levels and adjusts flows accordingly.

48 It appears to me that re-hydrating the soil requires a regime of monitoring that is onerous and unreasonable without any guarantee of it being successful. In reaching this conclusion I have not disregarded the ability to have an automatic water delivery system installed. Such a system, however, would not solve the practical problems of measuring and monitoring moisture content and wall movement in order to test the effectiveness of the treatment and to avoid the rebound effects that may be occasioned by over-saturation. As a remedy it becomes all the more problematic when one has regard to the likelihood of on‑going (and perhaps more severe) water restrictions in metropolitan Adelaide.

Conclusion

49 There being no evidence to the contrary I accept, for the purposes of these proceedings, that the subject tree provides an important environmental benefit. The tree is in good health and is yet to reach maturity.

50 However, I am prepared to uphold the appeal, reverse the decision of the Council and thus allow the removal of the subject tree. In light of its health, its expected longevity and the desire in the Zone to maintain landscaping I am on the one hand, reluctant to do so but on the other, satisfied that the evidence, when properly weighed and considered, justifies this course being taken when one has regard to Principle 179(a)(iii).

51 This conclusion is reinforced by the terms of the text in support of Objective 56. I do not think that the decision to grant consent, when the evidence is properly considered, would be construed as allowing the indiscriminate or inappropriate removal of the subject tree. The subject tree is a major contributor to the desiccation of the soil upon which the footings of the house sits. The water needs of the subject tree are causing the desiccation of the soil and thus the footings to subside. This, in turn, has caused the rotation of the superstructure and in turn cracking of the walls. There are, no doubt, other factors at work. They might need attention as well. However, while the subject tree remains, desiccation and footings instability will continue.

52 I informed the parties of my conclusions in the above terms by memorandum dated 20 August 2008 and opened the question of the imposition of conditions. It is often the case where a significant tree is to be removed, a Council seeks to impose conditions that have the effect of replacing the tree and generally enhancing the landscaping. This is all the more important in circumstances where, as in this case, the objectives for the Zone and its stated desired character make specific reference to the importance of vegetation in the streetscape.

53 By email dated 16 September 2008, Mr McElhinney advised that the Council does not seek any conditions being imposed.

54 The appeal is allowed.

55 Development Plan Consent is granted to Development Application No. 090/1062/2007/C2 for the removal of a significant tree (Eucalyptus camaldulensis) at 42 Northgate Steet, Unley Park.

56 There will be an order to that effect.

Just unbelievable that a council dig their heels in that deep to prevent a property owner from dealing with an issue without having the property owner taking legal steps to allow a commonsense fix to the problem.

If it was a Council building receiving damage from a tree, it would be felled in a heartbeat I bet.

I actually disagree ( to an extent ). I've seen too many cases where mature trees have been felled for somewhat dubious reasons although as in the description above there was sufficient reason to do so. I'm lucky ( or is that unlucky depending on your point of view ) to live on the so-called " Leafy North Shore " where most of our local councils have a pretty strict policy on tree removal and I'm thankful for that. We have a very green suburb unlike some of the wastelands I see in other areas. If there are major structural reasons why a tree should be removed I don't have a problem with that and I know some species like the RRG above shouldn't be within a bulls roar of a house. I do think though that if a tree is to be removed another non-invasive or one that doesn't get higher than say 6m should be planted in its place.

Stewie ( waiting for Qebtel and his chainsaw to chime in here )

There is also a responsibility on the design engineer to allow for the effect of existing tree
in their footing design.
And in justme15 situation this is a very important point.
Did the engineer design accordingly, assuming the trees are the problem which has yet to be established.