Gwynne Anthony 2020

ART506 Dissertation 2019. Anthony Gwynne . 29 (iii) Roofs - should be constructed as follows: (a) resist the penetration of precipitation to the inside of the building; and (b) not be damaged by precipitation and not carry precipitation to any part of the building which would be damaged by it; (c) be designed and constructed so that their structural and thermal performance are not adversely affected by interstitial condensation. It’s interesting to note there are no diagrams in the Approved Documents for roof guidance details and a typical modern form of construction used today is illustrated in Figure 9 . Figure 9: Principles of modern construction (Source: Gwynne, 2013). WATER WATER RAIN Rain runs down internal face of external wall leaf and evaporates or runs harmlessly away over dpc tray Rain runs down internal face of external wall leaf and evaporates or runs harmlessly away over dpc tray Water gets stopped by polythene membrane in floor and dpc in walls WATER VAPOUR Water vapour evaporates through a 'breathable roof membrane' or eaves ventilation *Note: Elemental U-values for Wales are shown. Damp proof course 150mm min above GL Plaster finishes Double glazed window (U-value 1.6*) Dpc tray over lintel vertical damp proof course SECTION DETAIL OF A TYPICAL MODERN HOUSE EXTENSION GROUND LEVEL (GL) Cavity wall (U-value 0.21*): Render finishes 100mm conc block 120mm cavity with 70mm partial fill insulation (leaving 50mm clear cavity) 100mm insulation block Ground floor (U-value 0.18): Screed/finishes 100mm conc slab polythene separating layer 120mm insulation 1200g polythene damp proof membrane (DPM) Roof (U-value 0.15*): Roof tiles/battens and felt stops the rain. Roof trusses (or cut roof) supports the roof coverings. 150mm insulation fixed between ceiling joists & 150mm laid over First floor (acoustic insulation laid between joists) Partition walls (acoustic insulation fixed between studs) Concrete foundations Damp proof course 150mm min above GL Thermal bridging