Nambucca Engineering can provide Soil Classification to AS 2870 for your house or shed project. Soil testing is important as it informs the foundation design for the structure.
Why do I need a Soil Classification
Different soils act differently when subject to wetting and drying. Clay soils shrink and swell when subject to wetting and drying actions, meaning that the soil that your house is sitting on will expand or contract. House footings must be designed to take into account the movement of the soils due to wetting and drying.
Selecting the wrong foundation type can lead to structural issues such as cracks, misaligned windows and doors, and shifting foundations, making it vital to get this step right.
The optimal time to arrange for soil testing is after selecting the building location but before finalizing the construction plans.
When should I get a Soil Classification
If you are constructing a new home or a new shed that is ancillary to a residence then you will need a Soil Classification so that the structural engineer can design your footings.
If you are conducting renovations to an existing home, and are expanding the footprint so that the house will need more footings then you will likely required a Soil Classification. However, if you still have the Geotechnical report from when the house was constructed then you can use the Soil Classification provided in the report.
How does Nambucca Engineering do Soil Classification
When you engage Nambucca Engineering to do a Soil Classification you will be contacted by one of our Geotechnical Technicians to organise a time to visit your site for testing.
The Geotechnical Technician will then do a borehole and log, a Dynamic Cone Penetrometer (DCP) Test and collect one or multiple soil samples.
The soil is then taken back to a NATA accredited lab where Shrink Swell tests are conducted to calculate the characteristic surface movement of the soil, which is then used to give a Soil Classification.
What do the Soil Classifications mean
Soils are categorized using AS 2870 into the following classes:
- Class A: Typically consists of sand or rock. This type of soil is stable and unlikely to react or shift with changes in moisture content.
- Class S: Likely contains some clay content. The ground may experience minor movement with changes in moisture content.
- Class M: Contains a moderate amount of clay or silt. Changes in moisture levels are expected to cause a moderate degree of ground movement.
- Class H: A highly reactive clay site. Significant ground movement is expected as moisture levels fluctuate.
- Class E: An extremely reactive clay site. Substantial ground movement is anticipated with changes in moisture levels.
- Class P: Referred to as a “problem” site, where the soil may have difficulty bearing loads or where ground movement could be influenced by factors beyond normal soil reactivity. Sites are often classified as Class P due to issues like soft soils, poorly compacted fill, erosion, moisture problems, presence of dams or trees, and drainage issues, etc.
How long does it take?
If you are within our service area Soil Classification reports are generally completed within 2 weeks of commission. If the soil is more reactive then the testing will take longer, and the report will be completed within 3 weeks.
Do I need anything else?
For most houses and sites the geotechnical testing and soil classification is all that you need to inform the design of your footings. However in some rare circumstances you may need a specialist geotechnical engineer to investigate and provide advice. Some examples of this include very steep slopes, sites with a history of land slips, sites with sinkholes, ex mining or quarry sites etc.
Where do I go from here?
Contact our team today to arrange a Soil Classification.
