Wattle & Daub: Craft, Conservation & Wiltshire Case Study
Contents
Title Page
1 Introduction
2 History
3 Craft
3.1 Diversity of Style
3.2 Frame Preparation
3.3 Panel Types
3.4 Staves
3.5 Withies and Laths
3.6 Daub
3.7 Decoration
4 Material Characteristics
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
4.2.1 Evaluation of Dung Ingredients
4.2.2 Lignin
4.2.3 Urine
4.2.4 Microbial Debris
4.2.5 The Role of Dung
4.3 Fibre
5 Conservation
5.1 The Value of Wattle and Daub
5.2 Defects and Decay
5.2.1 Decay of Daub and Plaster
5.2.2 Decay of Withies, Lath and Staves
5.2.3 Maintenance
5.3 Repair
5.3.1 Partial Renewal
5.3.2 Removal of Impermeable Paints and Coatings
5.4 Replacement
5.4.1 Brick Infill
5.4.2 Renewal
5.5 Building Regulations
6 Wattle and Daub in Wiltshire
6.1 Documentary Evidence
6.2 Geology and Land Use
6.3 Fieldwork
6.4 Surveyed Buildings
6.5 Evaluation
6.6 Wiltshire Conclusions
7 Conclusion

Title Page Previous Next | Material Characteristics >Soils >Strength

4.1.3 Strength

A weak daub may fail if it has insufficient cohesive strength to prevent it delaminating from the wattle or from failure within the body of the clay. In a vertical panel the critical stress is shear. The strength of a soil sample can be measured in the laboratory using either the vane method or small shear box.[56] After application, a daub is not under a compressive load and will therefore fail in shear if its ‘apparent cohesion’ is exceeded.[57]
[56] BS1377-7:1990.
[57] The apparent cohesion can be determined as the y-intercept from a graph of peak strength versus normal (compressive) stress.