Tips & Tricks

The Two Pronged Assault on Slab Heave

Slab Heave in the News

I have been following, with interest, the recent spate of slab heave issues in the western suburbs of Melbourne. The recent VCAT decision against Metricon (Hooper v Metricon Homes Pty Ltd (Domestic Building) [2014] VCAT 277 (18 March 2014)) (and the latest decision against Metricon) is the very tip of the slab heave iceberg in Melbourne and the rest of the iceberg is yet to show itself. There are many more affected home owners with under-performing slabs affected by slab heave.

(Edit 2019: Ha! Opal Tower is now the tip of the iceberg – and it’s a big iceberg!!)

Construction Professionals Take Note

However I have been reminded this week that the assault on slab heave is not and should not be just a single pronged attack by individual home owners attempting to wrangle acceptable performance from their individual slabs.

The problem is an industry wide problem with indictments of under-performance by a whole swathe of contributors. Good performance of a waffle slab or raft slab is not an issue a single home owner nor one a single VCAT decision is able to make an impact on.

Construction industry professionals are putting themselves at risk by cutting corners or being coerced into accepting poor construction practices.

This needs to stop.

Consumers vs the Building Industry

The issues are numerous and complex and consumers and providers can both accept a portion of responsibility:

  • Consumers are demanding larger houses and better finishes for less money.
  • Suppliers are competing to provide more for less.
  • Earthworks testing doesn’t find every problem on a site which leaves houses at risk.
  • Builders are using cheaper construction professionals to cut costs and strong-arming suppliers into providing unsatisfactory designs.

What is the Solution?

We need a two-pronged attack on slab heave. These are my recommendations:

The proactive solution:

  • Builders shouldn’t be able to manipulate or coerce suppliers. An industry watchdog is needed to receive complaints  from industry professionals that are being forced to bend to the builder’s demands.
  • An overview committee is needed to review and monitor the way individual builders and their inspectors operate.
  • Regulations are needed to control and enforce professional indemnity insurance held by consultants in the building industry. Building owners and builders need someone to sue when something goes wrong.
  • Builders need to be aware that it is nearly impossible to protect waffle slab systems against uneven soil moisture conditions – particularly in highly reactive clay sites. Failure of the soil moisture maintenance system, even if it is within the homeowner’s care, will not necessarily void the builder’s responsibility for maintenance and/or replacement of the building (particularly those offering long (25 year) warranties.

The Fix-up Solution

  • A national taskforce is needed for soil testers, engineers, designers and builders to improve knowledge of slab heave and rectification methods. For too long this information has been a closely guarded secret held by senior engineers. Share the knowledge or loose it.
  • Improve public awareness of the importance of soil moisture maintenance. Improve the transmission of this information to future owners of houses on reactive clays.
  • Improve public awareness of acceptable cracking limits in brickwork and plasterboard walls.