If you are buying vacant land with the intention of constructing a dwelling, we recommend that a soil test be carried out prior to purchasing the land, provided the vendor does not have a recent report to provide you.
Reactive soils are clay-type soils that swell on wetting and shrink on drying.
The soil type is classified by a testing procedure as part of the building planning/approval process. However, we suggest that soil testing to be carried out prior to purchasing the land as if the result is reactive soil it would more than likely be required that your builder will need to install additional reinforcements to the slab of your home. Obviously, this would be an additional cost by your builder but would eliminate or diminish the chances of your slab cracking due to dryness or sinking when the soil dampens.
For ‘highly’ and ‘extremely’ reactive sites and problem sites a structural engineer will need to do a special assessment and advise on how to safely build a house without the risk of damage due to soil movement. You may even wish to have a structural engineer inspect the land prior to signing a contract who will assist you in determining whether certain slab reinforcements are going to protect your home or whether it might be worth looking at other blocks of land for your home purchase.
We do not want to see anyone buy land that they want to build their dream home on, to be advised that they can’t construct or that even if they did a decade or two down the track of the soils creating forces that would damage your home.