Buying or selling a property with foundation issues

Purchasing and maintaining a property is for many the biggest investment of their lifetime.

When a property is on the market, there will often be the need for compromise. For sellers, the final sale price is typically the biggest compromise, while buyers usually need to be flexible regarding the location, layout and size. However, expensive structural repairs may be a deal breaker for many homehunters.

Being informed is the best protection against major unexpected issues or costly repairs after the contract of sale is signed. A visual inspection is recommended to identify minor defects and potential maintenance issues, as well as a thorough inspection by a qualified building inspector to help identify major structural faults or safety hazards that may not be visible at first glance.

Understanding wall cracks and soil types

While many astute homeowners and buyers will recognise wall cracks as warning signs of potential subsidence, not all wall cracks indicate major foundation issues. The type, size and location of cracking can help to identify the extent of the issue, and possible solutions. For example, cracks that are 5mm or wider, extensive stepped cracks in brickwork, or complete separation in the mortar or cement between bricks may be cause for concern.

If the building foundations are affected by ground subsidence, the underlying reason may not be immediately obvious, and further investigations are highly recommended before finalising the sale.

The common causes of foundation ground issues often relate to moisture in the soil beneath the home’s foundations. Different types of soil behave in different ways to changing moisture levels, so consider the following when investigating the likely cause:

  • water ponding around the house,
  • excessive moisture leaking into the foundation ground, often due to broken pipes, making it too wet
  • invasive tree roots searching for water, making it too dry.

The value of building inspections

Fair Trading NSW recommends investing in a pre-purchase building inspection to gain specialist advice regarding any major problems, and how the issues may affect the property over time. The inspection report can help determine future maintenance plans, with the cost of major repairs able to be factored into the purchase price.

By inspecting the whole property, especially drains and gutters, sheds, pergolas, retaining walls, windows and roofing, inspectors look for signs of structural problems and differential settlement. It is recommended that you familiarise yourself with local pre-purchase building inspection guidelines as states and territories across Australia and regions of New Zealand vary and some things may not be checked.

Extensive foundation damage should also be fully assessed by a suitably accredited structural or geotechnical engineer, to identify the cause, how extensive the settlement is, and whether the underlying cause of settlement has been fixed.

Remediating the issue

In many cases, foundation issues can be resolved quickly and efficiently using modern ground engineering solutions that are less invasive and costly than traditional underpinning.

After purchasing a 12 year old property in England, the new owner discovered differential settlement had affected the site, leading to uneven subsidence by as much as 82mm. The subsidence needed to be addressed before other renovations could commence.

Mainmark was able to resolve the issue in less than five-days using JOG Computer-
Controlled Grouting which provides an extremely precise method for stabilising soils, consolidating weak ground, and raising foundations to deliver specific, engineered outcomes.

The process was completed without any need for structural demolition, destruction of landscaping, or interference with floor slabs. With access via a shared driveway, Mainmark worked closely with neighbours to plan works to minimise disruption.

Work together for a better outcome

If the new home of your dreams is affected by ground subsidence, it may not necessarily be bad news, however, you will need to make an informed decision. Do your research and consult experts, before agreeing on terms of purchase with the seller.

Some homeowners prefer to remediate issues prior to sale. The owners of a clifftop property in Auckland sought a solution for substantial ground settlement which had affected the front wall of the home, causing cracks in masonry walls, the driveway and lawn area.

Mainmark’s Teretek® engineered resin was injected through tiny tubes, rapidly expanding to improve ground bearing capacity, re-levelling the home in careful increments. The entire process was completed within a day, without any need for excavation works that may have further damaged the property or grounds, and allowing the owner to proceed with the sale.

Remember that fixing the problem for the long term requires correcting any issues that might have caused the foundation damage, and this may also involve consulting a plumber or other expert. The CSIRO guide to foundation maintenance is also a valuable reference.

Mainmark has treated tens of thousands of sites throughout Australasia, from single-storey homes to large commercial buildings. For more information and advice about ground engineering issues and remediation solutions, contact Mainmark on 1800 623 312 in Australia or 0800 873 835 in New Zealand.


By James O’Grady

James O’Grady is a Sales and Business Development Manager at Mainmark. He is a civil engineer with 25 years’ experience in structural engineering, construction materials and ground treatment.