Cob Builder
Build and repair with cob — the traditional monolithic earth building material of South West England — for heritage conservation, new build ecological housing, and SPAB-compliant repairs.
High
Moderate
2–4 years: DEBA and SPAB courses plus apprenticeship with an established cob builder
No statutory registration; DEBA member/Craftmark accreditation; SPAB earth building courses; EBUKI training network; CSCS card for construction sites; practical experience-based learning is the primary route
common
What you do
Cob builders construct and repair using cob — a monolithic earth building material composed of subsoil clay, aggregate (sand and gravel), water, and long straw, mixed and built up in lifts without formwork to create load-bearing external and internal walls. Cob building is a living vernacular tradition in Devon, Cornwall, Somerset, and adjacent counties, where an estimated 50,000 cob buildings survive. New cob construction has experienced a revival as an ecologically sustainable, low-embodied-carbon building material with strong thermal mass properties.
Work encompasses both repair of existing cob structures — removing damaged sections, preparing the cut face, mixing matched cob, and building up replacement material in consolidating lifts — and new construction: testing and blending site subsoil, mixing cob by foot, mechanical mixer, or harrow, lifting and ramping cob onto the growing wall, and trimming the face on each lift as the material firms. Finishing involves external lime render to protect the cob from rain penetration, and limewash for the final breathable finish.
The Devon Earth Building Association (DEBA) is the principal professional and advocacy body for cob and earth building in the UK. The Earth Building UK and Ireland network (EBUKI) provides broader professional connection. SPAB and Historic England's guidance on earth building supports heritage repair work. Training is available through DEBA, the Building Limes Forum, Ty-Mawr Lime, and specialist courses at sustainable building centres.
Why this career is resilient
The stock of historic cob buildings in the South West requires ongoing maintenance and repair that can only be carried out in cob or compatible earth materials — cement repairs are damaging and incorrect. Planning authorities in Devon, Cornwall, and Somerset require cob repairs to be in cob. The revival of new cob construction — driven by sustainable building interest and the material's genuinely low environmental impact — is creating a growing new-build market that complements heritage repair work. DEBA's Craftmark accreditation scheme provides professional differentiation for qualified practitioners.
A typical day
Morning: begin repairs to a storm-damaged cob wall on a listed Devon farmhouse — cut back the damaged section with a hand saw to a sound face, rake out loose material from the base, and prepare a cob mix using site clay, coarse sand, and chopped barley straw. Afternoon: build up the repair in 150–200mm lifts — tamp each lift firmly, key the surface for the next, and cover with damp hessian to slow drying. End of day: assess the set of the morning's lifts, trim the face with a spade to a clean plane, and check the repair height against the coursework.
Routes in
Full-time college course
Study full-time at a further education college, usually for 1–2 years. You will need to fund yourself or apply for a student loan (available for Level 4+ courses).
Employer-funded training
Some employers — particularly the NHS, emergency services, and larger care providers — run their own funded training programmes. You apply for a job and train as you work.
Pay and costs
Earning potential: Employed cob builder: £25,000–£35,000. Self-employed cob specialist with heritage and new-build commissions: £30,000–£50,000.
Training costs: DEBA membership and training: £200–£600. CSCS card: approximately £36 plus test. Tools: £200–£400. Materials are generally site-sourced clay and straw.