Thursday, 20 September 2007

wattle and daub

(from wikipedia) The earliest form of wattle and daub known was constructed with the wattles, commonly in the form of hazel branches, woven around evenly spaced vertical wooden posts set in the ground in a circular formation. Wet clay daub was then smeared onto the wattles, filling in the gaps. Archeology shows the techniques used were numerous and their boundaries ill-defined. A typical hut might have a conical roof that was steeply pitched to allow proper shedding of the rainfall. Hazel battens were tied horizontally to provide a framework for thatching to attach to the roof. The bottom ends of the rafters were tied to the vertical wall posts.
Wattle and daub arose from the combination of two wall forms: wattle walls, which used the same techniques as fencing for boundaries, and the earthen wall. Wattle walls may have been filled in to improve wind resistance with anything on hand such as straw, moss, leaves and earth. For binding, it was easiest to use soil that could be pressed into position and would remain in place. In a study conducted by G.D. Shaffer it was discovered that occasionally the daub was burnt, to be hardened like pottery. Hardened fragments of daub could be found in fresh daub coats, which Shaffer theorized was used to help strengthen the integrity of the wall (Shaffer, 2003).
Those areas rich in timber allowed for a more sophisticated style like timber frame, with holes and grooves integrated to place vertical staves in order to prevent bowing or detachment in high winds. When the Romans arrived in Britain, there is little effect seen on the use of wattle and daub. We do see the integration of straw, hay, vegetable materials and dung to improve binding and reduce shrinkage and cracking. Also, remains of Anglo- Roman wall daub reveal herringbone keying, an indication of a plaster finish, a new development in weather resistance.
As the craft of the English carpenter evolved the timber frame house also evolved into a more popular, sophisticated housing choice, and wattle daub was the infill of choice. This crafts popularity stems much from the low cost and abundant availability of the materials. The abundance of wood allowed structural framing to include a high number of supporting posts, creating close-studded style paneling. This form of paneling required a variation on the style of infill, where instead of woven wattles, straight laths were held in place by channels and then daubed. Then, as timber became increasingly scarce, the ratio of infill to timber walling increased to created wider panels. These square panels still required intermediate supports between the studs causing the use of staves and woven wattles to return. Note that although there is little archaeological evidence, it is clear that wattle and daub was used to complete the walls of true cottages up to the 19th century. Clearly, wattle and daub may have lost its popularity with more upscale styles, but remained the poor man's wall.
One clear disadvantage of wattle and daub has always been clear: its vulnerability to damp. If not kept dry, wattles have a tendency to rot, or be attacked by beetles causing the daub to crack or become loose due to becoming exposed to moisture and frost. Areas most affected tended to be along the bottom of the panel. The jettied frame (Jettying) is possibly a system that evolved as a way to keep walls drier where upper levels are extended with a cantilever system. Lime (calcium oxide) wash and lime plaster were used to fight the effects of rain. These two coatings provided a strong surface as well as sealed cracks in the daub. An unavoidable effect was that created by the combined flexibility of the frame and shrinkage of the earth and lime materials, creating cracks between panel and the surrounding frame. This factor caused wattle and daub structures to be draughty and required constant repair of the panels. The final move to improve weather resistance was seen east of England where the entire wall was plastered, seen accompanied by decorative plaster known as pargetting.
A noticeable focus on wattle and daub is apparent when examining the History of Ireland. Early Irish settlements were built using this building method already in the Neolithic, maybe as early as 6000 BC. Some of the most well-known constructions to use wattle and daub were the Crannógs. These were fenced-off lakeside sites on islands (often artificial) linked to the land by a bridge or boat. The huts or houses had wattle and daub walls. Some sites remain today, but the structures are long gone. A modern reconstruction of a crannog can be found at Craggaunowen, County Clare in Ireland.
A look into the history of the practice of doing wattle and daub shows an obvious niche for specialty. At York, in 1327, it is recorded that the mixing of earth with straw and stubble was for use by a 'torcher' or 'dauber'. The term "torching" applies to the process of covering walls, ceilings, as well as the insides of roofs and chimneys.
In the case of a primitive and peasant buildings the wattle and daub work was done by the home owner. For wealthier home owners the work was done by a dauber, a position well established in the ranks of craftsmen, though not as well respected as those who designed the house and constructed it. The demise of this art is driven by several factors. Replacement with brick nogging (rough brick masonry used to fill in the gaps between timber members) is one factor, where decaying wattle and daub panels were replaced by brick work. The use of timber framing diminished in the 17th and 18th centuries due to fire risk and the move to stone and brick housing. When half timbering become less respectable in the 18th century the desire for stone and housing facades become prominent, causing timber walls to be modernized by either full plastering or tile. Wattle and daub is said to have been conveyed a poor image through law supposedly inspiring the term 'breaking and entering' due to the ease with which criminals could enter by breaking through the infill (Graham, 2003).
This method of walling remained practically unchanged from primitive building to its demise in the 18th century. Wattle and daub has weathered periods of great change and innovation and remained unchanged despite huge developments in the craft and housing style surrounding each panel. The basic methods and materials used have remained the same.
Daub is a mud like sealing layer generally created from a mixture of certain ingredients from three categories: binders, aggregates and those used for reinforcement. Binders hold the mix together and can include clay, lime, chalk dust and limestone dust. Aggregates give the mix its bulk and dimensional stability through materials such as earth, sand, crushed chalk and crushed stone. Reinforcement provided by straw, hair, hay or grassy materials help to hold the mix together as well as control shrinkage and provide flexibility. (Pritchett, 2001).
Styles of panels
As discussed earlier there were two popular choices for wattle and daub paneling: square paneling and close-studded paneling.
Close-studding panels create a much more narrow space between the timbers; anywhere from seven to sixteen inches. For this style of panel weaving becomes too difficult so the wattles run horizontally and are known as ledgers. The ledgers are sprung into each upright timber (stud) through a system of augured holes on one side and short chiseled groves along the other. The holes (along with holes of square paneling) are drilled at a slight angle towards the outer face of each stud. This allows room for upright hazels to be tied to ledgers from the inside of the building. The horizontal ledgers are placed every two to three feet with whole hazel rods positioned upright top to bottom and lashed to the ledgers. These hazel rods are generally tied a finger widths apart with 6-8 rods to each 16 inch width. Gaps allow key formation for drying (Sunshine, 2006).
Square panels
Square panels are large, wide panels typical of some later timber frame houses. They have a square shape although sometimes they are triangular to accommodate arched or decorative bracing. This style does require wattles to be woven for better support of the daub.
To insert wattles in a square panel several steps are required. First, a series of evenly spaced holes are drilled along the middle of the inner face of each upper timber. Next, a continuous groove is cut along middle of each inner face of the lower timber in each panel. Vertical wattles are then inserted, known as staves, and these hold the whole panel within the timber frame. The staves are positioned into the holes and then sprung into the grooves. They must be placed with sufficient gaps to weave the flexible horizontal wattles (Sunshine, 2006).
The origin of the term 'wattle' as a term describing a group of acacias in Australia, is from the term "wattling". In early Australian European settlement the acacias were commonly used in wattling, and the name became shortened to wattle.

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