New Forest Cob Cottage Restoration

In 2002 my wife and I purchased a property in Wootton, Hampshire, to be used as our main home. With so much potential this attracted a number of prospective purchasers, including some property developers with plans to flatten the site and construct two houses.
 

The property featured in a well known home magazine - described as a "stonking plot!" - by no means an architectural gem but bustling with character. 

The property at the start of the project...............original cob building on the left, with flat roof extension at front and brick extension on the right. What a mess!

 

A few days into the project.....note the awful flat roof extension! Going, going......

 

Gone.....

The orginal building comprised of a material known as cob - basically soil mixed with straw and stones. In 1980 a very ugly brick extension was added to the property and we believe that in the 1950's the glass conservatory, shown above, was constructed. 

Rear elevation - cob against brick (left)..........

 

 

A mortgage was taken out on the property and the building society instructed their surveyor to compile a report. The list of problems was endless - subsidence, damp, tree problems, wood worm, etc. etc.

The state of the flat roof once the felt had been removed........

 

Our first port of call was to invite a structural engineer to the property to report on the subsidence. He suggested a series of tie bars to run the length of the building - like you see on old properties that have circular or cross shaped brases on the outside walls which basically hold the building together or stop walls bulging outwards. A damp proofing company was invited to the property who reported that all of the cob walls were damp and needed to be damp proofed using a plastic membrane - almost a rigid form of bubble wrap. We were also advised to fell a 1000 year old (approx) Yew tree that grew by one of the cob gable ends.

I had worked with different period building materials (chalk, wattle and daub etc.) but never with cob. By chance one morning I was on the internet and happened to stumble across the web site of a company based in Winchester called The Lime Centre. The gentleman that I spoke to, Mr R. H. Bennett MBE, explained to me that the advice that I had received to date was incorrect and suggested a site visit to discuss the matter further. A few days later Mr Bennett visited the property and provided me with his professional comments on how to address the problems raised. Firstly, don't allow the damp proofing to go ahead. Cob needs to "breathe". The property had been unoccupied for approximately 12 months prior to us purchasing it, and the heating had not been on. Damp readings were bound to be recorded! Secondly, forget installing tie bars. Cob, later described by a specialist structural engineer that I used in central London, is a "plastic" like material. If it wants to move - it will! The tie bars would be a waste of time. Instead I was taught by Mr Bennett to "stitch" the crack in the wall back together. Imagine standing in front of a solid, 18" thick exterior cob wall with a large crack in, and removing on the inside at floor level enough cob to receive a cob "brick". Once completed and installed I then cut out the same amount of cob on the outer face of the wall, but at a "bricks" height difference to create a kind of stitching effect. This was continued along the seem of the crack. 

To date, no crack has returned and the works were carried out 6 years ago. The works are not structural, but certainly appeared to have done the job. I also learnt that  ventilation is important for cob, so we ran in a series of vents in order that the cob walls could be vented by the air from outside. Other useful comments from Mr Bennett comprised:

  • Keep your gutters clean of vegetation and debris - very improtant in the case of cob
  • Expose the orginal fireplaces (which we did) and use them as often as possible. This is an excellent form of convection
  • Never use any cement based products with cob. The entire exterior of the property was rendered using a lime based mix purchased from the Lime Centre
  • Do not use standard masonry paint on the outer rendered walls. Instead we used limewash - a painfully slow and laborous method of painting which allows the cob to "breathe" but at the same time does not allow the moisture from rainfall to penetrate into the lime based render mix.
 

Then came the issue of where to extend the property to provide more space. Numerous schemes were considered and a decision was eventually made to extend at the front of the property to provide an additional bedroom, open galleried staircase / landing and a family bathroom. All of our neighbours approved the scheme and soon afterwards planning permission was obtained from New Forest District Council. We did not want the new extension to stand out, so we sourced original second hand Welsh slates for the roof and rendered the exterior elevations of the new build, using lime, to match the existing building. This also applied to the extension constructed in 1980.

The extension at the front, where the flat roof extension once stood...........

The lime render been applied and installation of the timber windows....

The property today.....

The photographs only represent a very small portion of this complex project, however hopefully you will see what can be achieved when a great deal of time, thought, effort and care is applied to an old building. 

John Nimenko

East Book House
East Street
Wimborne
Dorset
BH21 1DX

Tel: 01590 381467
Mobile: 07968 395425
E-mail: jnimenko@mail.com