Design of foundations and footings can vary considerably depending on the type of soil and design of home.

A typical slab-on-ground base may have a number of engineered features to deal with the natural soil movement, the more reactive the soil type, the more extensive the engineering of the slab. Thickening beams, piles, and waffle design may be employed to further stabilise foundations.

Apart from the design and engineering of the base  it is also just as important that the base is constructed correctly.

What We Inspect at Base Stage...

This depends on slab design but for slab-on-ground constructions the following are checked:

• The site identified by means of Builder's sign or survey pegs. Site conditions including access, driveway slope, retaining walls and fences.
• Orientation of the building in relation to the access road. Weather conditions and site gradient.
• The position of the external wall location in relation to the footings and the inclusion of reinforcement starter bars tied to the slab mesh. The steel visually checked for clearance from the base (40mm) and from the slab finish (no less than 20mm).
• Under-slab services including drainage, plumbing, electrical, phone/data checked for defects, and quality of materials used. Installation of stormwater pipe system.
• Termite control including the type and location of barriers relative to drainage pipes.
• The location of the electrical meter box including the provision of a safety switch.
• The site checked for possible termite nesting sites and other conditions conducive to termites.
• Visually check that the site is clear of building rubbish and materials are stored appropriately.

More of What We Inspect at Base Stage...

Site Conditions:

• Site Gradient
• Cut/Cut & Fill/Fill
• General Soil Type
• Orientation to road
• Weather: Raining/After rain/Dry
• Surface drainage
• Subsidence
• Seepage
• Retaining Walls & location

Site Improvements/Conditions:

• Landscaping
• Driveways/access/slope
• Crossover
• Paving
• Fencing
• Builder's sign/site identification
• Stormwater pipes

Floor Structure:

• Footings
• Formwork/brick base
• Damp-proofing membrane
• Steel placement and fixing
• Thickening beams/piers
• Sub-base compaction
• Floors below ground level
• Suspended floors

Under slab Services:

• Sewage pipes
• Plumbing
• Electrical
• Phone/data cable
• Termite control

Information on Foundations:

A house needs a foundation to shoulder its considerable weight, to provide a level base for construction and separate wood-based materials from ground to prevent decay and undetected termite infestation. Concrete is the most common material used for foundations.

Most houses have a raised, perimeter foundation that supports floors and load-bearing walls. Some are built on a flat, concrete slab that provides both a base for the structure and the bottom floor of the house. Older homes tend to rest on a series of concrete piers. Other houses utilise all these methods for different portions of the house. Houses with perimeter foundations for example, often have post-and-pier supports beneath a beam that runs under a load bearing wall along the middle of the house.

The base of a foundation or footing is generally wider than the foundation wall and is designed to distribute the house's weight to prevent future settling or movement.

There are three types of conventional concrete foundations: poured concrete, concrete block, and post-and-pier all regulated by Building Codes. A poured-concrete foundation may be a raised perimeter foundation, a flat slab, a combination of the two or a monolithic slab where footings, foundation and slab are a single, integral unit.

A conventional perimeter foundation has a poured concrete wall supported by a poured concrete footing. Both are strengthened by steel reinforcing rods and used in connection with both raised floors and slabs.