Beautiful boulder clay

This unprepossessing grey mess I collected in a bucket is boulder clay. If you’ve got a house with clay walls, it’s like finding a seam of valuable minerals. There’s no clay to beat it.

Our part of Suffolk mostly sits on thick layers of the pale grey, white-flecked natural building material, laid down by glaciers grinding their way over chalk. But it’s usually deep down and hard to find.

It comes near the surface here, because that’s why our pond exists, sitting on an impermeable bed of clay. But it’s not so easy to dig out without draining the pond, which we think was once a clay pit.

Digging a trench to plant a hedge yesterday I kept finding lumps of it, deposited there after earlier work on the pond. It has got muddy, but that doesn’t matter – a bit of earth won’t spoil its performance.

Not only does it make a good, plastic clay for wall repairs when mixed with straw, it is also less prone to shrinkage cracks than ordinary yellow clay, and dries as hard as a lump of chalk.

If you have clay daub walls and come across any, store it till you need it. Wonderful stuff.

Repairing the damage 

The first step is to prepare some of our grey boulder clay, which we saved from the excavations for the extension. It is much better than the brown clay we used previously when we bought ready mixed daub from a farm in Essex.

We pounded the clay lumps with the end of a piece of timber until they became like smooth plasticine. Continue reading “Repairing the damage “

Back to daub

005 (3)
Exposed clay daub

After focusing on  a new timber framed extension for so long, we’re now back to repairing the old building. Weak bits of of a rough cement render have been dropping off  the front wall, as the picture shows. The cement is just a thin layer skimmed a few decades ago onto clay daub.

We’ve been expecting this, but took a decision early on to let it happen by natural weathering, and then patch repair bit by bit.  Looking at the evidence of what’s there, we think patching is the way the walls have been maintained for a very long time – any weakness, then they just slapped on a bit of clay and limewashed it, and owners only recently took to adding cement as well. Continue reading “Back to daub”

Wonderful clay

The grey, chalky pond clay makes a great building material
Pond cleaning in 2011: the pale grey, chalky pond clay makes a great building material. (The darker areas are pond mud on top of the clay).

Postscript on wattle and daub – 2013

We have a great resource in the pond, which we knew about from when we drained it in 2011, but we had not appreciated until this year its amazing building material potential: pale blue-grey boulder clay, which underlies much of Suffolk. Continue reading “Wonderful clay”

Wattle and daub – inside repairs

There was some damage to the inside panels of wattle and daub during the replacement of the sole plates. The building contractors re-rendered the bottom 30 – 50cm cm or so of the outside of the wall to weatherproof it over the narrow gap that appeared, using lime mortar. But on the inside there were a number of breaks and gaps in the clay where the old panel infill fell out when the building was lifted. Some thermalite blocks, which had been used in previous repairs, also fell out.

Fitting hazel ledgers and sticks to an empty panel

The empty panels were filled from the inside with clay daub. After letting the work dry and crack for six weeks we put on a clay plaster made from daub mixed 2:1 with lime mortar and finally a thin coat of haired lime plaster bought ready-mixed from Anglia Lime. This was also used to plaster the thermalite blocks which had been used to fill in the old kitchen doorway, and was very effective in strengthening a section of old crumbling plaster in the kitchen. Continue reading “Wattle and daub – inside repairs”

More repairs – 2010

  • Chris and I filled the very large number of holes left in the kitchen and living room by the replacement of the sole plates, including some complete damaged panels. Wherever possible, we used hazel lattices and clay daub for the repairs, with a skim of lime render inside, finished with limewash. We salvaged old clay and plaster. See ‘wattle and daub’ and ‘wattle and daub inside’ posts.
  • The interior ground floor woodwork was painted and the brickwork limewashed.
  • An electric storage heater Aga was installed in the kitchen.
  • We deliberately spurned a fitted kitchem. The idea is that separate pieces of kitchen furniture unattached to the walls allow the walls to breathe and stay dry – important given our repair philosophy of using the natural characteristics of the materials to keep the building dry through encouraging breathability.
  • We paid two local landscapers to lay hardcore and a stepping stone path from the entrance to the front door, and to make a small brick patio outside the front door, linked to the doorstep by limestone slabs on a brick plinth. They also made a low brick wall to hold back the slightly higher level area outside the kitchen window, which we gravelled. They erected a garden shed we had bought.
  • A fencing contractor installed a full size five bar farm gate. We later replanted the damaged hedge either side of the gate with hawthorn and field maple.

Continue reading “More repairs – 2010”

Further work – 2009

 Further work 2009

Summer, autumn, winter

Celebration - moving in!
Celebration – moving in! May 29, 2009.

  • The east wall was repaired with clay, but in patches where there were holes, and on the north wall there were also areas that needed repair.

    New Morso wood burning stove
    New Morso wood burning stove
  • We planted a beech hedge on the north boundary of the kitchen garden.
  • A Morso wood burning stove was installed by us in the sitting room. It has a rated output of 10Kw maximum, though we were toild to take all these measurements with a pinch of salt. It does however create a lot of heat that spreads throughout the building after a few days, as the massive chimney brickwork warms.

Continue reading “Further work – 2009”

Wattle and daub

We learnt the basics of wattle and daub on an Essex County Council course at Onchors Farm near Braintree. The course tutors were Lydia Bucknell and Peter Roe of Traditionally Plastered. This was a prelude to a long term programme of repairs to the daub, inside and outside.

The first thing to think about is a supply of clay daub. On the course, we learnt to make it ourselves. The basic ingredient in that part of Essex was a pale yellow clay, containing small chalk pebbles, from a pit on the farm, which was quite  similar in texture to the material in the walls of our cottage.

This was was the kind of repair we had to tackle – deep damage to the clay panels.

At Onchors farm, the clay was mixed with sand, chopped straw and cow manure and then trodden (literally) until the texture changed to plastic and doughy, not unlike plasticine. It took 3 people 30-40 minutes to tread one large wheelbarrow load into the right condition. Traditional builders used to short circuit this laborious process by leaving cows tethered in the clay pits to tread the mixture. Modern machinery can be used to make daub in quantity, but do not use cement mixers, because the material is too glutinous. Onchors farm has a machine very like a large bread doughmaker, with rotating arms. Given our experience of DIY daub making, we decided to buy ready made daub from the farm in tubs. Continue reading “Wattle and daub”