Gwynne Anthony 2020

ART506 Dissertation 2019. Anthony Gwynne . 86 General Guidance Traditional buildings (built before 1919) Buildings built before 1919 are normally constructed with solid walls typically of natural stone or brick in lime mortar (or cob) with lime render and plaster finishes. This type of construction is termed ‘traditional construction’ which is naturally porous and allows the building fabric to ‘breath’ naturally through the permeation of water vapour. It does not incorporate the barriers to external moisture such as cavities, rain-screens, damp-proof courses, vapour barriers and membranes which are standard in modern construction. As a result, the permeable fabric in traditional structures tend to absorb more moisture, which is then released by internal and external evaporation. When traditional buildings are working as they were designed to, the evaporation will prevent trapping of water and keep dampness levels in the building fabric below the levels at which decay can start to develop. This is often referred to as ‘vapour permeability’ or a ‘breathable building’. As traditional buildings need to ‘breathe’ the use of vapour barriers, non vapour permeable insulations, cement renders, gypsum plasters and other impermeable materials commonly found in modern buildings must be avoided when making improvements to energy efficiency, as these materials can trap and hold moisture and create problems for the building and potential health issues for the occupants. The use of new materials for any upgrading works to traditional buildings should be vapour permable and need to be based upon an informed analysis of the full implications of their inclusion in order to minimise the risk of problems arising. Further guidance on the use of vapour permeable construction is provided in the ‘Traditional Buildings Compliance Guide’ in support of this Approved Document. In addition to the compliance guide ( see paragraph 7.3 ), additional information in the form of simple diagrams for the upgrading of vapour permeable construction could be included in the Approved Documents. This additional information should be kept very plain and clear and very simple as those already contained in the current Approved Documents, not to make it too complicated. An example of what the additional guidance could look like in Approved Document C is illustrated in Figures 45 and 46.