Concrete Relevelling in Brisbane

What concrete relevelling in Brisbane actually involves

The test is simple enough to try before anyone is called. Lay a straight edge 3 m long across the crack or step, centred on it, and measure the gap beneath. Under 15 mm sits within what QBCC treats as acceptable under the Standard, and over 15 mm does not. The result says whether the slab has moved more than the Standard allows; it does not say why.

Raising a slab, or fixing why it sank

One way to level a settled foundation is by injection. Buzzi, Fityus and Sloan, in a 2010 paper in the Canadian Geotechnical Journal, describe injecting expansive polyurethane resin under a structure in small steps until it reaches the level wanted, and call the method not well documented in the literature. The resin injection page sets out what they found. Whatever the method, CSIRO says the remedy for movement caused by a water service or drainage failure is to repair that failure.

When a subsidence complaint is lodged, QBCC's inspectors take a set of floor levels and record them on a floor plan for later assessment. A slab that has sunk within the builder's responsibility window, 6 years and 6 months from the start of the work, is a matter to raise with the builder first. A dated measurement of your own, taken before anything is touched, is worth having either way.

Concrete Relevelling in Brisbane — common questions

Is a sunken slab always a foundation problem?

Not necessarily. A slab that fails QBCC's tests can still have several causes, and CSIRO lists erosion, saturation, tree roots and leaking pipes among the usual ones. Which one applies to a given slab is what an inspection is for.

Is relevelling a slab licensed work in Queensland?

Building work above A$3,300, materials included, needs a QBCC licence. QBCC's list of licence classes has none called relevelling, and we have not been able to establish which class covers it, so ask the provider which class they hold and what it covers.

Will a levelled slab stay level?

The one peer-reviewed study we have read, abstract only, found that resin cannot stop the soil rehydrating, that rehydration may swell the levelled foundation, and that the long-term risk of lifting it too far is limited. It says nothing about a slab whose cause is still active.