Wattle & Daub: Craft, Conservation & Wiltshire Case Study
Contents 2 History
3 Craft
3.3 Panel Types
3.4 Staves
3.6 Daub
3.7 Decoration
4.1 Soils
4.1.1 Constituents
4.1.2 Plasticity
4.1.3 Strength
4.1.4 Field Testing
4.1.5 Selection
4.2 Dung
4.2.2 Lignin
4.2.3 Urine
4.2.4 Microbial Debris
4.2.5 The Role of Dung
4.3 Fibre
5.2.3 Maintenance
5.3 Repair
5.3.1 Partial Renewal
5.4 Replacement
5.4.1 Brick Infill
5.4.2 Renewal
6.3 Fieldwork
6.5 Evaluation
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5.3.1 Partial RenewalThe most frequent repair scenarios are cases where a
significant proportion of a panel remains sound. The failed parts may require
remedial work to the wattlework, lath, daubs, renders or, most commonly, a
plaster top coat.
Plaster Coat Where only a top coat of plaster has become loose, it may be replaced as follows:
Where the plaster had been decorated, several principles of conservation can conflict. On the one hand, it is recommended that the historic decoration should not be imitated where the craft has been lost and so the plaster is left plain or an ‘impression’ of the decoration is used. Conversely, such detailing of buildings is often important to their appearance and one should endeavour to employ crafts such as decorative plastering and pargetting so they are not lost. In this case, one might re-instate the decoration, perhaps dating it to prevent confusion with regards to authenticity. Wattlework Withies and woven lath are often friable due to decay. However, the principles for the repair of wattlework are as follows:
Where decay is localised, new sections of withy or lath should be ‘slipped in’ to the existing wattle so to avoid unnecessary stripping of sound daub:
When introducing new wattle or lath to a building, there is a risk of introducing a new infestation of wood-boring beetle. Where a previous infestation has been found and there are no signs of recent activity, it is likely that that the remaining timber has become unsusceptible: either the conditions are unfavourable or vulnerable wood has already been attacked and the beetles’ supply exhausted. However, where a timber frame might remain vulnerable to attack, pre-treatment of the new wood with insecticide represents a sensible precaution. With withies and laths, pre-treatment should be highly effective since the slender sections can be saturated with the active insecticide. In this situation, the treatment is perfectly targeted and the (valid) concerns relating to the treatment of historic timber are not applicable. There are many proprietary formulae, commonly using permethrin as the active ingredient, which may be water or solvent based and suitable for brush or spray application. Lath The approach to repairing lath is similar to that of wattlework in that replacement is limited to the need for forming a sound backing to failed daub or render. Repairs should be from similar material to existing. Sound laths that have loosened due to corroded nails can be reattached. It is essential that the laths are not re-nailed since the vibration may cause daub or friable plasters to crack. Instead, they should be secured using brass or stainless-steel screws. Splitting of the laths is not a concern in new work but movement of laths may disturb attached daub. Therefore, the drilling of pilot holes in the lath is recommended. Daub Cracked or loose daub should be conserved as far as practicably possible. If external daub has cracked, eroded or delaminated from its backing, then attempts to secure it should first be tried before considering replacement. Where decay only affects part of a panel, replacement can be limited to the unsound area. Cracked daub, where otherwise sound, can be consolidated using a lime mortar:
Where a regular programme of limewashing is
established, hairline cracks may be left: the cracks are likely to be filled as
part of the cycle in which a limewash of ‘creamy’ consistency should
be used (e.g. 1 part mature lime putty to 5 parts water).
Where large pieces of daub have become detached, they should be replaced like-for-like using daub, rather than filling the void with lime mortar. If mortars are used habitually to replace daub then the cumulative effect will be the loss of integral wattle and daub panels and may encourage the demise the craft of daubing. Where the detached daub has been salvaged, it can be reused to avoid unnecessary labour. It should be prepared by breaking into pieces and saturating in a bucket of water, stirred, and then left to resettle. The scum of old straw, hair and dung should be removed from the top. The daub should then be laid out until its water content is suitable for use. Hair or chopped straw and cow dung may then be added and the mix reapplied. The preparation of new daub is described in Section 5.4.2. When replacing onto historic wattles, it may be wise to prepare the mix so it is a little wetter than compared to a daub for new work. This should make it more malleable and help prevent damage to friable withies. The risk is increased cracking of the daub, but this may be simply rectified by reworking the surface[95]hen green.95 After considering all repair options, it may occasionally be decided that a panel cannot be saved due to the poor condition of its wattlework. In this case, a panel may require complete renewal. [95]
The term ‘green’ refers to a state during drying where a daub or
render has firmed up but still appears damp. It is also the state where the
material is still workable with a pallet knife or modelling tool without causing
the surface to break up, but does not cause the bulk of the material to
shift.
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