Solid Foundations

Western Australia consists of a range of different soil types, ranging from sands through to clays and rocks. Our Lead Architect, Mary Ong, talks about the importance of speaking to an expert when embarking on your home building journey.


Engaging a Structural or Geotechnical Engineer is imperative to determining the soil / site classification of your block and the classification should be completed to Australian Standards.


Choosing the correct Designer and Builder for your site is also critical. The appropriate Designer and Builder will deliver a home that will best suit the requirements of your site effectively and efficiently.


The type of soil that a house is built on affects site preparation and footing and slab details. More reactive sites will typically require additional site works and will in turn increase the overall cost of the building. 


Different Type of Soil in Perth Metropolitan


Predominantly, the Perth Metropolitan area has Class A sites – mostly sand and rock sites with little or no ground movement. However, it is best to have an expert determine your site classification. This should be done as part of the design and engineering phase.


*Other Classifications;

Class S – Slight reactive clay sites

Class M – moderately reactive clay or silt sites

Class H – Highly reactive clay sites

Class E – Extremely reactive sites

Class P – A problem site


*Source: A New House


Each classification determines the level of ground movement from moisture changes. It is important to have adequate drainage should your site be classified as reactive.


When we discuss designing and building houses, little is discussed about soil / site classification, more emphasis seems to be placed on orientation. As consumers perhaps we need to be better educated when purchasing a block, and if you don’t know…ask. 

Schedule an appointment with our award-winning team today.