Another defective house story

Ok Hart’s
When all else fails go and see the local mp . I have found that fur starts flying when they get involved. It’s a state matter so will be state mp.

If a large tree or a couple of trees in the same area are removed from the block on extremely reactive clay soils before house is built, what is sufficient time for soil moisture rehydration and normalisation of soil movements.

I have slab heave, one Engineer said 9 months, another 12 months and then another 6 years is sufficient time.

I was classified as E but I think it should have been P. The slab heave is occurring where the trees were removed.

Are there any documents or articles where I would find this information?

Were soil moisture levels taken pre build and normalised?

The drying effect trees have on soil is a phenomena known as Matric Suction. Googling that term will bring up a lot of information.

Responsible engineers often stipulate for constant watering to be applied to designated soil areas on kdr sites and the same should go for sites where large trees have been removed but unless things have recently changed, it is not mandated. For kdr sites, a two week watering regime is common but the length also depends on local climatic conditions.

As for waiting for normal rainfall to equalise moisture levels when there has been high matric suction in areas radiating from large trees, that again depends on 'normal' rainfall, the soil classification and the time of year but it could easily be up to 12 months,,,look at Melbourne's rainfall for the first 4 months of this year. Only soil moisture tests can give the answer, anything else is highly variant guesswork.

Thanks Save H2O for advice. Block was classified E and the statement on the site investigation report stated, “No existing vegetation on this or adjoining allotments within influence distance.”
A large tree was removed 12 months beforehand. There were a line of trees along the fence line and my garage was built against the fence line but apparently they say these aren’t an influence for the design of slab.
My house is 154mm out of level and one area has decreased 41mm in 12 months.
No one wants to take responsibility. Today I stuck my head up into the roof and see light coming through many areas. I just want someone to tell the truth. It’s not that hard.

I’ve been informed to get a quote from either a Quantity Surveyor or builder for a knock down rebuild of my home. Also informed I could get a quote from both.
Any advantages one over the other?

The saga continues. The 4 plumbers who each completed their separate plumbing works all completed non compliant work. Self-certification is a joke. They will all receive notices to return to fix, let’s wait and see how many do. One will be extremely costly.
Advice to new home owners, if you suspect there are issues, ensure you get it sorted within 6 years as you can make a claim on the plumbers insurance. This insurance is different to Builders Warranty Insurance which is junk insurance.

The regulatory bodies are also a joke. If plumbers or any other tradesperson are found to have performed blatant non compliant, sub standard work, they should be brought before a tribunal, fined, suspended and made to undergo reassessment and pass before being allowed to return to work under a monitored one year probationary license. If that happened as it should, the workmanship and adherence to compliance would improve dramatically, I am absolutely sure about that!

There should also be a thorough audit of all work they have done over the previous year and rectification offered to all previously affected home owners. Blatant non compliance/bad workmanship is rarely a one off situation.

Note that work can however be substandard yet compliant and what's more, the Australian Standards in part allow this. As an example and because you also have non compliant stormwater drainage, for urban housing blocks under 1,000 sq m and as per AS/NZS 3500.3.5.5, sub surface stormwater pipe design "shall be determined according to local practice and experience (without specific design calculations)". Plumber's self certification loves that one and is why (cheaper) 90mm pvc stormwater pipe is often used instead of larger 100mm pvc Drain Waste Vent (DWV) pipe even when the drainage volume for a 1:20 Average Recurrence Interval requires by calculation the larger 100mm pipe.

90mm pvc stormwater pipe is measured as an outside diameter, the internal diameter is 86.2mm which has a volume of 5.8 litres per metre.

The stronger 100mm pvc DWV pipe has an outside diameter of 110mm and an internal diameter of 104mm which gives a volume of 8.5 litres per metre, a volumetric increase of 46%.

SaveH2O, I totally agree with the fines etc. Until this happens, non-compliant work will continue and houses will suffer. The consumer is the one that ends up paying. All they need to do is fix there defective work and take a photo and send to the regulator to show they have. What sort of regulation and penalty is that?

It's like the term 'deemed to satisfy', deemed to satisfy who? Themselves and the Building Surveyor who ticks the boxes to continue getting more work from the builder? When did that AS come into effect or has it always been there?

No surprise I have majority 90mm pvc pipe and 100mm down the driveway, even though I have a letter from the Engineer to the builder stating a detention system was not required and reduce the pipe to 90mm pvc within the property. Also reduced pits to 300 x 300mm.

Deemed To Satisfy (DTS).

The National Construction Code (NCC) is a 3 part document comprising of the Building Code of Australia (BCA) which is Parts 1 & 2 and the Plumbing Code of Australia (PCA) which is Part 3.

The NCC is a performance based document, this means that the performance requirements of the NCC must be met but the NCC does not specify how this must be done. This is to allow for the introduction of new techniques and materials provided that those new techniques and materials satisfy the NCC's performance requirements.

At the basic level, the NCC is the primary document which calls up Australian Standards as DTS solutions. If there is a conflict between the NCC and the AS, the NCC has hierarchy because it is the primary document. A combination of the NCC and AS can be used.

On the same hierarchy level as AS are Performance Solutions. Performance Solutions need to be certified by an industry expert as satisfying the performance requirements of the NCC and many builders now include Performance Solutions into the contract. It should be noted that many certified Performance Solutions do not meet the AS or manufacturer's requirements. If there is a problem in the construction that cannot be rectified by a NCC or AS method, a Performance Solution often needs to be certified to affect a fix.

The NCC can also be overruled by local and State regulations even though the NCC is a national code. Some of these interferences are just plain ridiculous but don't get me started on examples of those!





I have the AS/NZS 3500.3 2003 edition and it is in there. As to when it was first introduced, I don't know. It has to be remembered that AS have no legal standing unless they have either been legislated or drawn into a contract. On 1 May 2011, the PCA was introduced into the NCC as volume 3. Prior to that, Victoria used the Plumbing Regulations which adopted the PCA in 2008 (2004 edition). Victoria has always excluded the BCA as a DTS roof drainage solution, using only the AS.

Section 5 of AS/NZS 3500.3 deals with SURFACE DRAINAGE SYSTEMS - DESIGN.

Two methods can be used to design drainage systems, the general method and the nominal method.

The general method requires calculations whereas the nominal method only requires local practice and experience.

Another problem with the Standards is the consultation of charts within the Strandards that show slopes and flow rates of different size pipes that show true diameters whereas most pipes are nominal sizes. For example, the internal volume per metre of a true 90mm internal diameter pipe is 6.36 litres per metre whereas the internal volume of a nominal 90mm pvc stormwater pipe with a true diameter of 86.2mm is 5.84 litres per metre. In other words, plumbers are basing compliance on smaller pipes from figures given for larger pipes! A true 90mm internal diameter pipe has 9% more internal volume than the commonly used SN2 (stiffness rating) 90mm pvc stormwater pipe which has 1.9mm thick walls and an outside diameter of 90mm.

EDITED: Typos.

With so many Standards, Codes, State and local government differences and top that off with self-certification, no wonder the building industry is failing.

Self regulation has left the lunatics in charge of the asylum.

Quis custodiet ipsos custodes?

Update:

My home is to be demolished. I have significant structural damage and it is no longer safe to live in. An 8 yr old home needs to be demolished because of absolute negligence. The regulators need to start regulating and not just token. The housing industry is booming and non compliance is rampant. Unfortunately for me and others going through this, it is way too late for anything to be done.

My neighbour cleared an area to prepare for the demolish and I was appalled what was found. So much for formwork, they used the existing fence the two years later fell down due to pressure. At least they used plastic. I will post these pictures up and lets have a game of spotting the defects!!

What a crack in the slab!

I'm sorry for how long this has dragged out for -thankfully, you received a positive outcome.

What do you mean by "they used the existing fence"? Do you mean they built the house against it?

WOW. All the best mate with the knock down and a new better home!

Hey Harts. Glad to hear your nightmare is coming to an end.

Who ended up paying for the rebuild? Are you out of pocket for just legal fees?

Yes, Lisa06, they didn't use formwork for the slab for the garage, they used the fence as the formwork. You can see it in this picture of the indents of the fence. Great brick work too. Interesting how the Building Surveyor approved this as one of the mandatory inspections is to inspect before the slab is poured.

Thank you. It's been a long battle and looking forward to my new and better home. Fingers crossed.