Wattle and daub is a composite building material used for making walls, in which a woven lattice of wooden strips called wattle is daubed with a sticky material usually made of some combination of wet soil, clay, sand, lime, animal dung and straw. Wattle and daub has been used for at least 6000 years and is still an important construction material in many parts of the world. Many historic buildings include wattle and daub construction.
Wattle and daub is the ancient equivalent of the plaster-board. Wattle and daub may not be the most rigid material, but therein lies its strength. It is able to accommodate even the most severe structural movement, it is usually well sprung into the timber frame and offers support to weakening timbers that other forms of infill might not.
Wattle and daub is not lightweight or flimsy. Its weight is not dissimilar to bricks, however its insulation is better and from a security point of view it can be far more difficult to break through than brick. Although wattle and daub is porous and moisture is absorbed when it rains, moisture levels are kept low because the daub acts like blotting paper to disperse the moisture and because of the high rate of evaporation from its surface.
To prepare, collect stout sticks that will be the posts. These are usually around 3-4 inches thick, straight, and about 6 foot in length, depending on the height of wall you want. Any wood will do, but the harder the better. Oak or Chestnut is best. Some say that if you char the wood over a fire, it lasts longer in the ground. Spike the end of the posts, and hammer them into the ground. Their spacing depends on how strong you need your wall. When it comes to depth, the deeper the better, but on the whole they don’t need to be very deep. About 40 cm is plenty for most applications.
Now harvest long, pliable sticks, that can be woven in and out of the posts. These can be branches, but they tend to snap more easily than young trees. Traditionally, the wood of choice is Hazel, for it naturally grows into long, pliable sticks. Then weave the bendy sticks, or ‘wattle’, in between the posts. They should be laid like bricks, in that a space between two sticks would have, above and below it, a stick of one continuous length. Where there is to a door, a post is to be inserted next to the door post, specifically to hold the wattle.
That’s the wattling done. Now mix together the daub of your choice. Daub is generally made up of a combination of ingredients shown in the table below.
|Chalk Dust||Crushed chalk||Flax||Urine|
|Limestone dust||Crushed stone||Hay or grass||Dung|
The binder holds the mix together, the aggregates give it bulk and dimensional stability, the reinforcement helps hold it all together, control shrinkage and provide long term flexibility. Some locally available materials may contain more than one of the aggregates and other ingredients.
For example, subsoil may contain clay, sand and earth. There is some debate over whether dung was deliberately added to daub mixes. It is probably reasonable to assume that the presence of dung in daub mixes was due to using old straw from animal sheds (why use fresh straw when it is valuable for animal bedding?) and using animals to do the hard work of treading the daub.
Water is added a little at a time until all has mixed and turned into a heavy paste. This mixture is the ‘Daub’, it protects the wattle wall from the elements, and prevents draughts. When the daub is ready, throw, or smear the it onto the wall. Both sides need to be covered evenly, and all sticks should be covered with at least an inch’s thickness of daub. Ensure that the daub is pushed into the gaps between the wattle. Now it needs to dry, and if desired after drying a finish plaster can be applied.