What is slab heave ?

For those interested here is a explanation of slab heave from first hand experience

Welcome to Cornell Engineers - Structural Engineerswww.cornellengineers.com.au

2019 was a very dry year in Melbourne metro but 2020 is shaping up to be very wet with total annual rainfall to date already exceeding the 2019 total by about 15% and the 1855 - 2015 January to May average total by more than 60% even though we are not halfway through May.

What advice would you give to those who built on highly reactive soil during last year's dry?

Inner Melbourne and just north of inner Melbourne experienced very dry soil moisture conditions and consequently a lot more tree damage which is still occurring in those areas.
There are not so many new constructions in those inner areas so we probably won't see the
large number of slab heave as we did see at the end of 2015 and 2009 in the outer new housing estates.The outer west and north housing estates soils are fairly moist and have been for a while so they probably won't see too much heave or limited heave.
Those who have built in the dry years should try to keep the soil moisture around their house from becoming very wet. There are several steps to do this
and the first and the most important is a properly constructed path around the outside of their home. Don't water along the house walls and don't put pebbles or gravel down as landscaping cover.
Properly maintain plumbing including gutters etc.
These are some of the biggest factors in reducing the potential for slab heave after construction especially the properly constructed path.

Insider - thank you for the link to this article. The information rings true with my property which has slab heave. Often the property owner gets the blame but with further investigation the slab heave has been caused by the reasons in this article. In my case, broken sewer and stormwater pipes but also the builder not using temporary downpipes when the roof was installed, plus many more instances of non compliance.
It will be interesting what the studies find with the methods for rectification that are being trailed. Unfortunately the damage to my home is substantial and the only option is knockdown and start again.

With a broken sewer pipe, does the water seep along the trench where it connects to other outlets, as well as into the surrounding soils and towards the natural fall of the property?

With settlement, does the edge of the house sink and you would notice this in brick movement as you would when slab heave occurs?

Harts
Yes the sewerage will flow along the trench and will flow into any other trenches that crosses it's path.It will also flow along the edge beam and can even flow back under the slab if the sewer trench does not have enough fall, slopes the wrong way
or does not have a clay plug to stop sewer flowing back under the slab from a sewer pipe breakage.

Settlement can occur different ways but in general the edge of the slab will sink first and usually the most compared to
the slab further towards the centre. This is a common scenario with tree drying and floor levels can give you
a good indication where the source of the problem is.
With differential settlement you first see the articulation joints open up, window frames distort and if it continues then brickwork cracking and internal plaster cracking.

Thanks Insider for the information. It would be interesting with my home how much water also washed away the soil underneath the slab. With both broken sewer and stormwater pipes including insufficient grading (back towards house) the whole build is a dogs breakfast.

I will upload a few photos of my property in 2012 as it went on the market and now in 2020. They will show the significant heave at the north of the property and it has me stumped that the Engineers for the 'other side' are saying I have settlement at the south of my property. Insurers are giving me the runaround. The plumber walked away with an 'educational approach'.

Harts

I really hope it gets resolved for you. The first photo goes to show how much ground movement there has been.

Thanks Insider, yes, a good example of slab heave.

Unfortunately, noone is there for the home owner. Not the regulators, the government, the insurance companies. I am on my own battling them all and it comes at an incredible cost both financially and on health.

One day, I hope the rules change, the regulators start regulating and those who decide to build substandard and non compliant homes and apartments are made accountable and not just an 'educational approach' but huge fines. The consumer may then start trusting the building industry again. It would be great for the industry and the economy.

Harts, any update with you slab heave situation? I am going through something similar so I'd be interested to know how your situation is panning out.

Hi Adman, sorry to hear of the issues you are having with your home and the builder, who looks like he is playing 'the blame game', which is exactly what my builder and his builder's insurance expert Engineer did. Read the post on this site called, 'The Blame Game'.

I finally got an outcome before Christmas. The builder and plumber had substantial non-compliance and I have significant structural damage and slab failure with extensive heave. The builder is being still being investigated through the VBA (Victorian regulator). I put in the complaint in June 2019.

I have now moved out of my home and my home is being demolished and rebuilt depending on the moisture levels under the slab how long before the building can start to be constructed.

It has been an 8 year battle, but I wasn't giving in. The builder did do some 'bandaid' fixing and in the end was told by his lawyer not to do any more or have contact with me. His mistake really.

My advice just like H2O has mentioned is arm yourself with knowledge, listen to the experts on here and take their advice and don't believe anything the builder has to say or his 'experts'. Get your own.
Ensure you have everything in writing. Take lots of photos including date stamping them. I took the same photos in the same spot every month for years. This certainly paid off.
I thoroughly read the Engineers drawings and saw where there were discrepancies with what was actually installed.

I hired my own Engineer and a forensic Plumbing expert and their reports outlined where there was non-compliance including CCTV of the underground drainage system (which was non compliant) and also where the original Geotechnical Engineer, Engineer and builder also went against the Act, Codes, Australian Standards etc.

Good luck and keep fighting. Knowledge is power.