A self-build Devon cob house demonstrates how smaller projects can be hugely considerate
Dingle Dell is one of the most ambitious and spectacular buildings to have featured on the popular Channel Four series, Grand Designs.
Lovingly crafted from traditional Devon cob – a hardy mixture of clay-based sub-soil, straw and water – Dingle Dell is in the heart of the east Devon countryside near Ottery St Mary.
A self-design and build house featuring an accommodation annexe, garage/workshop and distinctive green wildflower roof, Dingle Dell is a zero-carbon project.
Dingle Dell is thought to be the biggest cob-built house in the UK and has taken three years to build, with a further year before it was fully habitable. Kevin said the secret of its durability was the clay in the soil which resists water and makes the building waterproof:
“What’s amazing about cob is how resilient it is to the weather. You would expect it to dissolve away but actually it is incredibly resilient. Cob has its limitations, but if it is used intelligently it is a really wonderful material.”
“I love the fact that it is from the site. It is non-toxic and is sculptural and most of all it is so beautifully comfortable to live in. A lightweight concrete block is three times as strong as this, but this is still strong enough for most situations. In terms of compressive strength, it is about a third as strong as lightweight block, but it is much more flexible and therefore versatile in its use.”
Building the house virtually single handed, Kevin estimates the project to have cost £750,000, not including his labour. Around 2,000 tonnes of raw material was sourced from the site itself; buying it in would have cost Kevin about £30 a tonne, so he has saved about £60,000 on raw materials.
The project has also cost Kevin thousands of hours of work – he was working 70-hour weeks during the summer for three years on Dingle Dell.
Kevin’s expertise at Dingle Dell included a striking tree sculpture connecting the two parts of the house. Outlining the main challenge of the project, he said:
“There have been times when I have felt pretty daunted at the scale of the project but I have never really wished to do it in another material. It is beautiful and so appropriate for this part of the world.”
Here are some examples of best practice initiatives carried out by Kevin McCabe to comply with the Considerate Constructors Scheme:
- External appearance of the project reflects its rural location, with boundary hedges laid two years before the Monitor’s visit showing regeneration.
- The removal from the boundary of a semi-collapsed barn leading to increased viewing of the construction work and its setting in open countryside enhanced the project’s appearance.
- The access lane and its hedging was free of litter and kept in good order, enhanced by the provision of a sponsored dog waste bin.
- The use of local, natural materials such as stone, clay and so on, meant few typical building materials on display, and limited mechanical plant, which enhanced the external appearance.
- The underlying values of the project, its use of materials, relationship to the landscape and its respect for resources were fully integrated into how the work progressed.
- Wide-ranging presentations were made to local groups and colleges and through other higher level presentations at academic seminars.
- A presentation was made in a high level academic seminar on ‘Earth Building in the Modern World’.
- Kevin highlighted the project through the town’s sustainability group, and Dingle Dell was opened to the public on its ‘open homes’ day, with proceeds given to local good causes. School children have also visited his remarkable dwelling.
- The earth building sector of the construction industry is being positively promoted by the project with its progress being tracked by Channel 4’s Grand Designs programme. This led to visits to the project by European students and national and European earth building organisations.
- The isolated position of the project limited the impact on others, however, close working relationships were formed with neighbouring farmers and walkers passing the site, all of whom were treated with respect.
- Kevin’s presence working on site and his relationship with local residents meant that any issues could be immediately addressed person-to-person.
- Information about the project was displayed at the entrance and further updates provided to reflect progress.
- The few deliveries made were directed to avoid the narrower roads in town.
- There was ample on-site space for vehicles and the lane was kept free of parked traffic at all times.
- Due to the location, the construction processes and the limited scale of the works, the project created the absolute minimum of nuisance and intrusion.
- The local economy was supported by using local labour (including the family) and the town’s independent building supplier.
- Timber came from a nearby Duchy source and slates were sourced from a local farm.
- This zero carbon project had an overriding commitment to the environment.
- There were links to academic research programs involving Plymouth and Bath Universities.
- One area of academic interest was the introduction of new materials into traditional construction techniques for the purposes of enhanced environmental performance.
- There was a short environmental policy but it was the overarching approach to complementing the environment that makes it absolutely clear that it was ‘deeds’ rather than ‘words’ that drove the project forward. This was promoted in the progress summary on public display.
- The project was a net exporter of energy to the grid from the large solar array installed on the earlier completed workshops. A total of 95% was exported and only 5% used on site, with very little diesel used in mechanised plant.
- A coppice comprising 850 mixed native trees was planted to provide a long-term supply of fuel for the wood burner stove.
- New reed beds were also established to further encourage wildlife, in addition to the coppice.
- Seed from a native ash tree was collected as a reserve supply in the event of disease.
- The carbon footprint and embodied energy was monitored as part of the Code 6 for sustainable homes.
- The cob construction process did not create any noticeable noise, dust or light pollution.
- Harvested water provided for all construction needs, which enabled independence from the mains water supply.
- There was virtually no waste; only one skip over a two-year period and nearly all materials were locally sourced.
- Unusable timber off-cuts and sawdust was fed to the workshop’s wood burning stove.
- The enhancement of the natural environment – its flora and fauna – was a core driver. The need to protect existing hedges and habitat was identified at the outset; hedges were rejuvenated, wild flowers have self-established and dormice have taken up residence.
- The ‘green roof’ created a wildlife meadow to complement surrounding meadowland.
- Further new habitat was created by leaving timber to biodegrade.
- Water courses crossing the site were protected from pollution and have been cleaned up.
- When implementing safety systems, advice was taken into account from the HSE (Health and Safety Executive) website and this reflected the micro-nature of the business.
- Safety training was provided at the outset for apprentices and visiting students.
- Kevin’s intimate involvement in all of the site works ensured a good balance between the work in-hand and safety standards.
- Near miss events were reflected upon as learning points and there was a focus on instilling the safety basics appropriate for the work in hand; the very small team and close working relationships provided unique opportunities for securing acceptable standards.
- The close working relationship between Kevin and the on-site team meant that levels of positive engagement remained high.
- Working hours were flexible to meet individual needs.
- Work clothing was provided and meals – breakfasts and lunches – taken communally with all on site (including specialist subcontractors), with the wholesome fresh food provided free of charge.
- Training on earth building techniques was advanced through the site team, visiting overseas students and an apprentice.
- Welfare facilities were available in Kevin’s home and the associated stand-alone annexe, with breaks taken in the dining area and the toilet and washing and showering facilities provided.
