New Home Build: What on Earthworks is it all about?

Jayde Ferguson

Building a new home isn’t just about the design and trappings. Whilst this tends to be the most exciting part for homeowners, the most important part of the process is getting the foundation ready.  Without a good starting point – a strong foundation to prepare the site on – it’s simply not possible to get the house of your dreams. One you’ve chosen your home design, the block to build on and all the finishes, the construction process begins. And it’s a big one!

Every homeowner should understand the construction stages to familiarise themselves with the build. For the foundation to be prepared at its absolute best, it’s essential the following steps are included in the development. Building a new home is an exciting project. But if the foundation and earthworks aren’t set up properly, it can be costly and stressful. Here’s what you need to know:

Soil Testing

Good foundations start at soil testing and reporting. Because it’s the soil that ensures the ground is adequately supporting your home, tests will need to be done to determine how secure it is. If the soil moves under the property after its built, the foundation of your home can be compromised. Geotechnical engineering reports decide how reactive the soil is (how much it will shift) and tests it for shrinking and swelling. Samples are taken from the site and studied in detail to outline their soil classification.

Each soil class relates to how much the soil moves. Soil that’s higher in clay content tends to shift more, resulting in a higher rating. This is because the clay absorbs water in wetter months and shrinks once it dries out. It’s these expansions that need to be measured in the soil to ensure the movement is combated. If the soil testing stage is skipped, it’s unknown how secure the foundation is and what subfloor suits the build. This can lead to significant structural damages to the home, which result in costly repair bills.

Site Classification

The site where your new home is to be built will be classed based on the soil testing. The site classification will give a detailed report for the property and what’s required to ensure the build has its required foundations. In accordance with the Australian standard, sites usually fall into an A (stable, non-reactive soil with little or no ground movement) or S (possibility of slight ground movement, often clay sites) category. These classifications determine what concrete footings and slabs are better suited for the foundation.

Earthworks and Ground Levelling

In preparation for the construction, earthworks and ground levelling need to be completed on site. A qualified earth worker will be provided with the soil classification and build plans to effectively remove stumps, roots and other organic materials left. This preparation ensues the land is completely cleared ready for construction so the build runs smoothly and safely. It’s important to note, earthworks can be delayed due to expected rainfall. Because of the work that goes into the site prep, land location, time of year, site and soil conditions are weighed up before a starting time is set.

Levelling and grading will ensure the house is being built on strong foundations too. Erosion and runoff are controlled as best as possible and machinery is used during these stages to level the soil on site.  

Preparing the Foundation for Strip Footings

Concrete footings and slab are poured after the stable earthworks foundation has been created. Pipe work is pre-laid and in place before the foots and slab are set. If the soil classification falls into a high category, it means the site soil is highly reactive clay. Ground movement is common as moisture changes and the site will require strip footing to keep the foundation solid.

Strip footing, when a concrete slab is placed in the trenches and reinforced with steel, supports the load of external and internal walls. Strip footings are always recommended as part of the construction process, but are vital for the higher soil classifications.

Keeping Your Foundation and Build Protected

Site preparation and earthworks are paramount to protecting your investment. There’s no use putting your money into building a new home that doesn’t utilise the proper resources for solid foundation or underestimates the importance of earthworks and soil testing. When the foundation is good, your home will be more secure with less structural and costly issues long term.

Author Bio:

This article is written by Jayde Ferguson, who writes for DM Civil based in Perth, Western Australia – providing tailored and sustainable civil earthworks and site remediation to Australia’s leading construction companies.