Embedded Files
We walk and run on the ground and minor ground movement is not a problem at all. In fact, we often see kids jump in and enjoy the mud puddle. This is all enjoyable because we have flexible bodies.
In contrast, your home is rigid and does not like any changes in ground conditions that push, pull, or twist on your building foundation.
Why is soil testing for construction necessary?
Imagine your home built on the ground as the diagram.
After a rainy day, the soil around your home absorbs water and expands. The expanded soil is blue in the diagram. The soil underneath your home will not expand. When this happens, ground movement will put pressure on your foundation. It will push, pull, and twist the foundation, especially at the edges where the wet and dry soil meet.
What is Soil Testing?
Soil testing, also known as geotechnical soil testing or geotechnical engineering, determines how much the ground will move after rain.
With the information in the geotechnical engineering report, your structural engineer can design a suitable foundation structure that can withstand the force from the soil movement after rain.
The Technical
In Australia, Geotechnical Engineering Report classifies your soil one of the following:
CLASS 'A' - Little or no ground movement
CLASS 'S' - Slightly reactive sites
CLASS 'M' - Moderately reactive sites
CLASS 'H1' - Highly reactive sites
CLASS 'H2' - Very highly reactive sites
CLASS 'E' - Extremely reactive sites
CLASS 'P' - Problem site or sites which cannot be classified as above
The amount of ground movement increases or becomes more unpredictable as your soil classification moves down the chart. This means your structural engineer will have to design a stronger foundation structure to make sure your home will stand the impact of the ground movements.
How much is Soil Testing cost?
Soil testing in Melbourne can cost anywhere from $600 - $900 for a standard home in 2020. It costs around $600 if your site is in Melbourne's metro area and you test on 3 locations in your site. The cost will increase if your engineer has to travel further, or if you need to test on more locations.
What's the Problem with Unknown Soil Conditions?
Poor design due to incorrect soil condition information will stop the whole building process until the structure is redesigned and a new building permit is obtained.
Waiting can easily add $3,000 of delay cost to you as the owner, plus any cost for redesigning, obtaining new building permits, and then building a stronger foundation.
The Common Mistakes to Avoid When Soil Testing
The two common mistakes that you should avoid are:
1. Avoid doing your soil testing too early
You need to map out the house footprint as you need to test where you plan to build your home. A meter or two away from the footprint is acceptable; but anything more than five meters away from your home footprint will increase your risk.
2. Not taking sufficient soil samples. You should take at least three samples so that your geotechnical engineer can work out a more accurate soil profile for you.
Call or ask us a question if you want to learn more about your project.
Disclaimer: We assume no responsibility or liability for any errors or omissions. The information is for general purposes only with no guarantees of completeness, accuracy, usefulness, or timeliness. You must engage a suitable consultant for your specific situation.
Google Sites
Report abuse