Solid foundations are the basis of a successful self-build project.
When it comes to a domestic building, the type of foundation required is often referred to as a ‘shallow’ foundation. Traditionally, this consists of a trench filled with concrete, usually around one metre into the earth. The house then rests on the concrete inserted into the earth and the weight of the walls and columns is transferred to the soil or bedrock.
If you are approaching a self-build project, it’s vital that before even beginning the first phase of construction work, you ensure you have done your research. Make sure you are aware of the previous use of the land and its suitability for building on. Arguably, paying for a professional ground survey is probably the single most important decision you can make when it comes to putting your budget to extremely good use.
Layout of services
After the ground survey has been completed and you are happy for work to begin, there are plenty of other factors that have to be considered to ensure that the foundations are a success. High on the list and absolutely crucial, is that you know the layout of services before breaking ground, laying foundations and constructing walls or subfloors.
Knowing where the services such as water pipes will be means that the necessary gaps can be left when constructing the walls. If services are not carefully considered, it could lead to changes to the foundations and walls having to be made in the future, which could result in a considerable amount of time and money being spent.
The issue of waste services is also probably one of the earliest decisions you will have to make. If you are building your home in the countryside – which a large majority of self-builders are – then it is likely that the property will be off-mains drainage. This means taking into account before the foundations go in — if the property will be serviced by a septic tank, a bio disc or connection to a sewage treatment plant.
So, in summary, once you have completed your ground survey, you know what type of ground you’re building on and you’ve talked to any trades working on the build about exactly where services will be going, then it’s at this point you should consider the foundation options available to you.
For many, the foundations have consisted of unsustainable wet concrete, however today there are other options available for constructing foundations which perform better thermally, are produced from recycled material and are less harmful to the environment.
A good example and worthwhile considering are foundation blocks which are made from aircrete (also known as Autoclaved Aerated Concrete, AAC). Aircrete is one of the lightest forms of concrete, but at the same time, it is fully load-bearing with a range of block strengths available up to 8.7N/mm2.
Foundation blocks offer excellent thermal performance and save both time and money which on a self-build project is a huge advantage. In fact, research by leading surveyors Davis Langon LLP has shown that constructing a foundation with aircrete foundation blocks is up to 24 per cent cheaper than cavity aggregate block foundations. They can also reduce ground floor heat loss by up to 25 per cent helping to reduce the need for additional floor insulation.
Sulphate & frost resistant
A further advantage is that below ground level, aircrete blocks are resistant to sulphate attack and frost damage, which means they can be used where other masonry types are unsuitable. They also have third party certification for use below the damp proof course (DPC) level in foundations.
If you are tackling the foundations of your home yourself, it’s worthwhile knowing that aircrete blocks are easy to use and can be cut using simple hand tools. One aircrete foundation block replaces two 100mm concrete blocks, which means that the laying rate is twice as fast. This means that foundation trenches can be backfilled as soon as installation is complete.
Building a successful foundation for your property is quite understandably a daunting task, even for the most experienced DIYer. There are so many different factors that can come into play and can cause serious and costly problems with the rest of the build, that it really is worthwhile looking into having a professional contractor install the foundations for you.
However, whether you decide to tackle it yourself or not, remember that as a self-builder you can turn to an experienced merchant for support in all areas of a project, from the foundations upwards. Jewson has been working with self-build customers for many years and has launched a dedicated, free Self Build Consultation Service designed to offer detailed guidance from the planning stages to final installation, regardless of the size or scale of the project