Foundations & Constructing Your New Eco Home
A self build eco home is a project that allows you to break from the normalities of construction and think outside of the box. It all sounds a surreal idea, after all, why change the whole concept of building in light of an entirely successful 20th century. But speak to the new age and they believe we have been building wrongly the entire time. Going eco can mean many things to different people.
Primarily it is energy saving but one can go further and suggest we need to build in an environmentally friendly way, not disturbing nature but blending in. While ensuring the carbon footprint of any new build is as low as possible and of course, ensuring from the top down, we make the use of most of nature’s offerings while ensuring the least amount of imported energy escapes. Eco centric foundations can not only cut labour costs but lower the carbon footprint of a home too. It can take less time to lay and also reduce the amount of required materials.
Firstly let’s look at the different soil types and foundation systems currently available and then move on to engineered and pre fabrication in tandem with other eco materials which can lessen on site labour and build duration and assist in furthering our aims of a home with ecology at its centre.
Soil Types And Foundation Systems
The objective of any foundation is to provide a load bearing platform that will not shirk during an earthquake or suffer subsidence and effective barriers are in place to deal correctly with natural drainage. There are a variety of different soil types around the UK which may prevent problems or not allow certain foundation systems from being used. Your architect will be able to advise on the best way to proceed.
Often build costs mount up depending on the foundation that is required so be sure to consider a soil survey when buying any plot of land.
- If you are lucky, the topsoil will have a bed of rock which is perfect to rest any home on top of.
- Requiring minimal excavation, any type of limestone, granite, sandstone, shale and firm chalk basing will simply need to be levelled off before minimum foundations are laid from which to build upon. Though you will need to pay special attention to drainage around the property as rock can be impervious and see standing water remain for a period.
- Softer chalk, gravel and sandy subsoil are best suited to a strip foundation system. Excavation to a depth of 700mm if often advised.
- Where firm clay lays over soft clay, or simply a clay subsoil then wide strip foundations and more commonly deep strip foundations will be required to ensure load bearing over a larger area with a deeper trench taking most of the stresses away from any movement in subsoil.
- On softer soil composites such as peat one of our more favoured solutions will bred to be put in place and that of a reinforced raft foundation. This in essence is a contained concrete base over a wider area than the build requires but has an excavation down to an accommodating load bearing depth. In most cases only 15omm is required with a raft foundation but peat being soft maybe need a reinforced platform with a 1.5 metre excavation.
Cancellation Of The Cold Bridge And Reducing Material Costs
One of the most popular eco home foundation systems are plays on the Scandinavian foundation system. They can effectively be built anywhere. We won’t recommend the best foundation to be used, as this really depends on the subsoil on your plot of land and that of the discretion of your architect and local authority planning department.
But through use of an insulated foundation strengthened by steel and overlaid by structural polystyrene with cement poured to an adequate depth, you can effectively cancel out so called cold bridging and have a base to your eco home which rates at a phenomenally low 0.10w U flooring value. Essentially, new building regulations are trying to achieve the eradication of a cold bridge in all new constructs.
The term’s definition indicates that heat can be lost to the cold of the ground and foundations themselves. With any eco home self build you are trying to achieve maximum sustainability, an environmentally friendly construction and one which maximises energy resources. Retaining heat while utilising natural products, natural energy resources and lessening expenditure on labour, materials and reducing build time.
Insulated raft foundations due to usually only requiring 15mm to 60mm of hardcore base can also bring down the cost of labour and materials further lowing your home’s carbon footprint. That said, there is still a revolution occurring across the foundation systems that are more traditional in the UK with a variety of different materials being tried and tested. Your architect may recommend different load bearing foundation systems on which to place your structure. A less intrusive system utilises pad foundations. These are put in place when structural columns require support for isolated loads.
While whole area excavation may be required for easier placement, you are effectively only laying concrete foundations where the columns will reside lessening the environmental impact and using less materials and labour. Other considerations might be Piled foundations, Trenchfill foundations (a cost alternative to deep strip foundations) and Stepped foundations for sloping grounds. These choices will depend on subsoil type and local authority requirements. In each instance it is possible to find a way to minimise environmental impact and decide upon material usage which aids in a much improved eco home foundation.
Floor Cassettes For Floor Structure And Alternative Base Materials
When it comes to laying the initial flooring over the foundations there are the usual considerations. Ones that run throughout a project. Those being
- Time, and
- Eco Efficiency.
However when it comes to flooring there are additional subsets of sound proofing, cold bridging and insulation. Much in the same as a timber frame can be assembled off site and imported, modern floor construction can be built the same way.
By using floor cassettes which are built in a factory and delivered you can save time on site and ensure strengthened joists and more increased spans and joint spacing allowing an architect to be more varied in the design process. Recent regulations insist that ground floors are insulated but many meet the bare minimum by using sheets of polystyrene with a screed on top. Though this can be tackled in many ways.
There are three types of flooring, solid concrete, pre-cast suspended concrete and or timber, which is obviously suspended by way of a joist hanger and Herringbone strut. Underneath the flooring you choose and as part of the foundations you could utilise a new material termed MISOPOR, a composite made of glass foam granulate. Which is highly load bearing, ecological – easily recycled and heat insulating.
Many self builds today choose the old Roman touch of underfloor heating. These can be electric or water based and tend to lay on top of the concrete flooring, once screed with stone or tiled floors laid on top.
It is important to consider your flooring options, as everything from door height to stairwells and height of the room will run off the initial plans. Failing to consider insulation options and underfloor heating at the architectural drawing stage may disappoint at a later stage in the build process.
Additional Ground Works, Supervision And Contractors
There are a multitude of contractors which are used in any self build. To reduce costs you can do a lot of the consulting work yourself but jobs such as bricklaying, roofing, new screeds, roofing carpentry, partitioning, suspended ceilings and dry lining, right down to building the timber frame on site will need organisation.
An architect can act as a liaison between building contractors to ensure this is a smoother process but as this is an eco home you may have additional requirements which you need relaying.
To reduce the carbon footprint of your self build and to maximise energy efficiency, ensure any schedule of on site time is coupled with that of projects which can be attended to at the same time. This may well result in length of build being shortened. Also consider which additional ground works need to take place, rather than seeing equipment leave site only for it to return.
- Do you wish to have solar panels in place? Will they be on the roof or on a separate area that requires a cement base?
- What about water efficiency? Do you wish to submerge a rainwater harvesting tank?
- Lastly, one item on the agenda that escapes many self build developers is who will watch the tools and materials on site and where will you live while house building? Some parts of an eco home project are not listed in an architect or builder’s construction plans but are equally deserving or hindsight.
When considering foundations, research ways in which to lessen the cold bridge effect
- A change in foundation system to utilisation of MISOPOR could be beneficial.
- When planning excavations, consider which other eco efficient accessories you may wish to put in place.
- Do you need to dig them in or attach them to the building before or directly after foundations are laid?
- If you wish to reduce noise on site and decrease site activity, and you are already having a timber frame sketch up and factory built, don’t forget the floor.
- Modern floor construction floor cassettes can be built off site too.
An eco home should be sustainable and alternative materials used wherever possible that are both renewable and recyclable should the building eventually go that way. Building construction is a large industry, be sure to check for the latest eco news and ensure your foundations are as environmentally friendly and have the least impact on the surrounding environment as much as possible and keep costs down by trying to source local materials (if possible) and labour.
To receive a free consultation and to discuss requirements for your plot of land, to draw up an initial concept before you submit planning permission, to ensure a proper feasibility study is undertaken and to gauge build costs. Fill out our no commitment, free consultation form so we can ensure a local architect attends to your needs straight away.