Firm foundations

If you’re new to self-build, working out which foundation application is best for your project can be one of the most daunting aspects of all the construction phases and is difficult to budget for accurately. Therefore, it is important to clearly identify the best foundation solution for your project early on.

Before you even set foot on site, it is strongly advisable to employ the services of a specialist engineer or soil expert to conduct a soil analysis. The integrity of your build may ultimately depend on the stability and strength of the underlying soil or rock. However, this is no usually a straightforward mater. In many cases the underlying matter may be a mixture of elements and form superimposed layers, each of which may contain a mixture of soil types.

Thankfully, there are a range of foundation solutions to meet every type of subsoil, ranging from traditional trench-fill or strip footing through to an engineered raft or even a pile solution. Make sure you consult with a local building inspector who will be able to agree you trench-depth on-site.

Informed specification

Where there is soil instability or potential settlement, your structural engineer will design a raft solution. This essentially integrates the foundation and slab into one concrete core with suitable reinforcement holding both together. Heavy clay soil usually requires deeper foundations, which can incur additional costs.

If conditions on site mean that you have to employ a special foundation, don’t panic. In reality, the costs can be easily absorbed during the build or covered by your contingency fund. In very worst cases, extra costs are unlikely to exceed 10% of the original budget.

In most cases home built with either timber frame or masonry will share precisely the same foundations and no distinction will be made between the two. In a few cases - where loads are critical - the lightweight timber frame or other prefabricated-type  structures may be able to have lesser foundations. This is particularly applicable with a piled and rig beam foundation, where it might sometimes be possible to reduce the number of piles.