Some terms relating to Construction and Building Elements are:
Footings: Houses, sheds, garages, etc need to have adequate foundations to support them and reduce the risk of damage occurring to the structure. Footing types can be either isolated (pad) footings, strip footings, Raft Slab footings, Waffle Slab footings (using polystyrene blocks under the slab), special suspended slabs, and also footings to take account of poor ground conditions such as filled sites and sites affected by Mine Subsidence.
There is an Australian Standard for Footing Design that is referenced in the Building Code of Australia. This standard is AS2870 – Residential Slabs and Footings, with the current revision being issued in 2011. This code details dimensions, reinforcement details, layouts and construction constraints for various types of footing construction.
The required type of construction is dependant upon the type of ground encountered on the site, that is in turn specified by a Geotechnical Engineer following site testing of your lot (Refer to previous blog post for further details). Site Classifications defined in the Standard can generally be grouped loosely into the following types of soil:
- Class A – Rock
- Class S – Sand
- Class M – Moderately reactive Clays
- Class H1 – Highly Reactive Clays
- Class H2 – More Highly Reactive Clays
- Class E – Extremely Reactive Clays
- Class P – Problem Site, e.g. Filled Sites, Sites subject to Mine Subsidence
The type of site (or the Site Classification) is specified by the Geotechnical Engineer and is based on the results of their testing. Different site classifications may also limit the type of construction that you are able to build on the site. For instance, cavity brick construction is not generally allowed on Class H2 Sites due to the risk of footing movement damaging the brick walls. Our next Blog post will go into more detail on the benefits of various types of footing systems.