Gwynne Anthony 2020

ART506 Dissertation 2019. Anthony Gwynne . 67 Conclusion of case studies The designs and specifications produced for the case studies and applied in the works phases are based on non- permeable modern methods of construction contained within the guidance in the Approved Documents. These are inappropriate for traditional, historic and listed buildings and can harm the building fabric and the health of its occupants. It makes building control position difficult when trying to enforce the requirements of the Building Regulations. Examples of the inappropriate specifications used in the case studies and the problems of potential harm are given in Figure 40 below. Specification Potential harm Ground floors taken up and replaced with concrete, incorporating a plastic damp proof membrane and closed cell insulation such as polyisocyanurate (Kingspan/Celotex) and polyurethane (Hexatherm). Traps moisture, prevents evaporation, reduces thermal performance. Moisture is pushed to the external walls, compounds rising damp problems which manifest within the building, degrading fabric and producing mould growth hazardous to the occupant’s health. Repointing and external rendering/internal plastering carried out using hard non- permeable cement-based mortars/gypsum plasters. Traps the moisture and prevents evaporation causing penetrating damp, degrading fabric and producing mould growth. New windows and doors, draught proofing including blocking up chimneys. Prevents natural ventilation and increased risk of condensation and mould growth Upgrading solid wall insulation (externally or internally fixed) carried out using non-vapour permeable closed cell insulation such as polyisocyanurate (Kingspan/Celotex) with non- vapour permeable finishes for example painted hard cement/sand render or painted gypsum plaster/board internally. Traps moisture, prevents evaporation, reduces thermal performance, degrades fabric, leads to efflorescence (Appendix K1 ), crypto fluorescence (Appendix K2) and produces mould growth. The risk of collapse to cob walling is high. Damage to structural timbers from fungal infestation (for example, dry rot and wet rot, Appendix K3) and insect infestation (beetle attack, Appendix K4) is high. Figure 40: Examples of inappropriate specifications and potential harm