Imagine this: you’re gearing up to lay the foundations for your extension, and in an ideal world, you’d be working on untouched ground in the middle of a field with no trees nearby.

Unfortunately, for most of us, this dream scenario is far from reality. Extensions often take place in established gardens, surrounded by mature trees, and on soil that presents its own challenges.

In some situations, you may find yourself needing to dig as deep as 2.5 metres, depending on the soil type and the influence of nearby trees. This depth can quickly turn into a logistical nightmare, especially when working in confined spaces like rear gardens, and if you dig beyond 1.5 metres, you’ll also need to shore up the sides of the trench to prevent collapses, which not only adds time but significantly increases costs. This is often the point where people start considering alternative solutions.

Piled foundations may sound like a good alternative, but they come with their own set of complications, particularly if access to the site is limited. That’s why many builders and homeowners turn to raft foundations. While this method requires a significant amount of reinforcement steel, it eliminates the need for deep excavations, making it a popular choice in tricky situations.

Before you start digging, it’s worth consulting the NHBC’s foundation depth calculator app. This handy tool can help you determine how deep your footings need to go, giving you a clearer idea of what lies ahead. Ground heave is another critical factor to consider. In some cases, you may need to install a clay master system alongside your footings or a cordeck heave guard beneath your floor slabs to ensure the stability of your build.