A “milestone” new home in our area is the first in the UK to be constructed using a new form of low-energy earth building.
CobBauge House in Fakenham, designed by Hudson Architects, is the first ever Buildings Regulations-compliant form of cob building, making an ancient building technique fit for purpose in the 21st century.
It involved a combination of hemp straw, water and earth - or mud - being used to construct the property.
Building this way is a technique that is considered to be highly sustainable and is centuries old - around 50% of the world’s population still lives in earth-based houses.
Work at the Fakenham home, located on Norwich Road, kicked off in 2022, and was recently completed - with a first look inside now on offer.
Anthony Hudson, director at Hudson Architects, said: “It is very exciting to see the CobBauge House finally complete, and it has been fascinating to be part of both the research phase as well as the construction of the house itself.
“Developing a traditional crafts-based system for modern-day application has been an extraordinary process, and it is amazing to think that this small house in Norfolk could be a milestone on our 21 st century journey to net zero.”
While earth is considered an ideal building material, it is thermally inefficient, and traditional cob walls would have to be more than one metre thick in order to comply with contemporary building regulations.
In contrast, the CobBauge House has demonstrated how earth building can reconcile modern building standards with viability, while using standard industry equipment.
The CobBauge system uses a 300mm inner layer of structural cob alongside a 300mm outer layer of insulating cob with hemp shivs – the chopped up, woody core of the hemp plant.
These materials are mixed separately with water, before being laid in a timber framework to dry out.
The resulting structure is well-insulated, and sufficiently airtight to satisfy modern building regulations.
In addition, CobBauge contains less embodied energy than conventional masonry, and the use of locally-extracted clay further minimises the building’s carbon footprint.
CobBauge House in Fakenham sits beneath a shallow roof designed to reduce the impact of the building’s volume and to complement its residential setting.
It sits upon a reclaimed brick plinth that lifts and protects the building material from the ground, while it also has a covered entrance area featuring an unrendered CobBauge wall.
The house has been carefully designed to minimise energy use. Large south facing windows are triple-glazed for winter solar gain, with shading for summer months.
Deep eaves also provide shading, and help to keep water away from the walls. Woodfibre insulation is used for the floors and roof. Heating and hot water is provided by an air source heat pump.
During construction, the team hosted a series of open days on-site as well as providing regular online updates.
However, Hudson Architects admitted that the prototype construction project revealed issues that will need to be addressed if earth building is to be made truly viable for the mainstream construction industry.
It said labour costs are relatively high, construction can be slow as it is weather dependent, and time needs to be given for each layer to dry sufficiently before work can continue.
Prefabrication is seen as a potential solution to these obstacles, and the next phase of the research project will now examine how CobBauge could be adapted to incorporate off-site construction.
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