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Cob builders & lime specialists in Dorset
Cob wall repair, lime render and breathable repairs that let historic buildings work as they were built to — across Dorset and the New Forest.
Our team have the specialist skills and experience required to construct or repair traditional cob walls, with a range of different approaches depending on what the job requires.
Colin’s knowledge of cob is recognised beyond our own projects: he provided his services in collaboration with the New Forest Conservation Department to put together a publication advising homeowners about cob buildings.
Cob wall repair & construction
Cracks in cob walls can be repaired structurally and/or cosmetically — either with cob blocks, cob made by reworking materials from the site itself, or cob made from quarried materials. The right method depends on the wall, its condition and the cause of the problem.
Damp problems are frequently caused by modern building practices being applied to older buildings — in particular hard, impermeable renders, mortars and plasters that trap moisture in walls that need to breathe. These can be effectively combated by removing the damaging materials and replacing them with traditional, breathable alternatives.
We can undertake any rendering, plastering or pointing in lime mortars, finished in the traditional way.
Lime render, plaster & pointing
We can undertake any rendering, plastering or pointing in lime mortars, finished in the traditional way. Lime is naturally breathable and flexible, which makes it the correct partner for cob, stone and other historic fabric — protecting the wall while allowing trapped moisture to escape.
How we work with cob & lime
- Cob wall construction, repair and maintenance
- Structural advice regarding cracks in walls
- Advice on damp and water ingress
- Removal of problematic, impermeable cement renders
- Lime plastering, rendering and pointing
- Specialist finishes — limewash, claypaint, distemper, mineral and silicate paints
There is rarely a ‘one size fits all’ approach to tackling problems in historic buildings — it often comes down to a careful choice between different approaches. That is exactly the judgement four decades of cob work brings.
New to cob? Our guide to caring for a cob & lime building explains why these walls must breathe, what damages them, and how they are correctly repaired and maintained.
Frequently asked questions
Why must I use lime, not cement, on a cob or old solid-wall building?
Old cob, rubble-stone and soft-brick walls were built to breathe — moisture moves through them and evaporates harmlessly. Cement render and gypsum plaster seal the wall, trapping damp inside. On cob this is especially damaging: trapped moisture can soften the earth, rot embedded timbers and cause render to blow off, taking the wall face with it. Lime mortar, render, plaster and limewash stay vapour-open, letting the wall regulate itself. It is the correct, compatible material for these structures.
Do I need Listed Building Consent for lime repairs or removing old cement render?
For routine like-for-like lime repairs on a listed building, consent is often not required, but you should always check with your local conservation officer first. Removing cement render and replacing it with lime can constitute an alteration that needs Listed Building Consent, and using cement on a listed building without consent is an offence. We routinely work to conservation standards and can help you prepare method statements and material specifications to support an application. When in doubt, confirm before work begins.
How long does lime render take to cure, and when can it be limewashed?
Lime cures slowly and on its own timetable — that is part of how it works. As a rough guide, a thin coat may firm up in a day, while thicker scratch and float coats typically need around a week each before the next is applied, and hydraulic lime can take up to about 90 days to fully cure. Limewash is then applied in thin coats — never fewer than five on fresh render — roughly one per day. Cold, wet or very hot conditions slow things further, so we plan the work around the weather.
How often does limewash need redoing, and is lime high-maintenance?
Limewash is a traditional, breathable finish but is not as durable as modern masonry paint — expect to refresh exterior limewash every three to five years. The upside is that re-coating is simple and inexpensive, with no stripping needed. Lime render itself, properly applied and maintained, can last decades. Lime render is best thought of as a sacrificial, self-healing coat that weathers in place of the wall behind it — modest upkeep in exchange for a building that stays healthy.
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