The term “square” is a reference from the English Imperial standard of measurement which applied in Australia prior to the introduction of the Metric system. In its day one square was the equivalent of 10 square feet. One imperial square is equal to 9.294 square metres. Government advertising regulations require that whenever an imperial measurement is quoted, the metric equivalent also needs to be disclosed.



A waffle slab is an “on ground” slab system as compared with a conventional or “raft” slab which is an “in ground” system.

A waffle slab essentially uses styrene pods above the ground to provide the form for the concrete pour, whereas a conventional slab has trenches excavated in the ground. Both systems are engineered designed and therefore deemed to be fit for purpose. It has been well documented that in recent years some major builders have had issues with a form of slab failure called “cupping”. Because these builders exclusively use the waffle method, by association, the waffle system has been interpreted by lay people as being the problem. The problem rather has been more a case of under engineering the slab during a period of drought without making sufficient allowance for the fact that when the drought ends and clay sites are subjected to water, the clay will
expand creating pressure on the slab.

At Highmark Homes we do not have a “one size fits all” approach towards slabs. We do not use waffle slabs exclusively. We also use conventional raft slabs. The decision as to the most appropriate system for the site will be made once a contour survey and soil test is carried out.  The slab will then be designed and certified by a qualified engineer.



The letters actually apply to the classification of the soil. The slab then needs to be engineered to be compatible with the soil type. So, an M class slab is essentially a slab designed for M type soil conditions and an H class slab is one that is designed for an H class soil. In fact since the slab failures encountered at the end of the drought, engineers deemed it necessary to further classify the H type into H1 and H2, with the H2 being a more reactive soil than the H1. The reactivity is generally due to the clay content and therefore the propensity of the soil to expand and contract in response to the addition or deprivation of moisture.

In the North and Western regions of Melbourne, it is uncommon for the soils to be classified as M. In fact it is more likely than not for the classification to be an H2. This is important to remember when obtaining a quotation from a builder, because a lot of builder use a base price method of quoting, which only allows for an M class slab. If this is the case, you will be charged more at a later date when it is established that your site requires a stronger slab.

At Highmark Homes we include an H2 class slab as standard.



All builders are subject to the same warranty obligations. There are 2 types of warranties.

The first one is in relation to maintenance of minor items. Generally the period is 90 days from completion.

At Highmark Homes we provide an extended maintenance warranty period of six months.

In relation to the “Structural warranty” a builder must take out warranty insurance (Domestic Building Insurance) with an approved insurer as one of the requirements to obtaining a building permit.

The insurance cover will provide protection to the building owner (in certain circumstances)for a period of 6 years for structural defects and 2 years for non structural defects- from completion of the home. Beyond this this period the common allows for domestic building owners to take action against a builder up to 25 years after the issue of certificate of occupancy or date of inspection of report to initiate proceedings.

Note: this scant summary is not intended as legal advice: readers are to obtain their own independent legal advice from a qualified legal practitioner.