LOGBOOK 7
Rubber
Naturally sourced from tree sap or synthetic (usual). Hard, low fragility, high ductility, highly flexible, waterproof, poor conductors (good insulators). Durable, high recyclability, cost effective. Uses: seals, floor lining, insulation, hosing and piping. Types: epdm, neoprene, silicon. Need protection from sun.
PLASTICS
Thermoplastics – mouldable when heated and become solid when cooled. (Recyclable). Eg: PVC, polyethylene. Uses: walling, roofing, pipes, skylights (Perspex). Thermosetting – can only be shaped once. Eg: laminex. Uses: insulation. Elastomers (synthetics and rubbers). Eg: neoprene, silicone. Uses: seals. DETAILING FOR HEAT AND MOISTURE Many are waterproof, lightweight, poor conductors (good insulators). Important to control heat and prevent moisture entering buildings. Eaves overhang structure to prevent water flowing inside. Double skin wall (brick cavity) Parapet walls DOMES & building SHELLS rather than internally. Box gutters drainARCHES, water outside the For water to penetrate building, must be an opening, water must be present at opening Curved way of spanning enclosed space as opposed to rectangular beams and force must be present to move water through opening. and columns. Sealants and gaskets deteriorate over time, need to be updated and maintained, rely on Arches curved structures for spanning an opening, designed to support insulation. vertical load by axial compression. The vertical forces transferred into Slopes used to divert water from walls at ground level and towards gutters and downpipes either side of the archway. Vaults which are extended arches, must be at roof level, counters gravitational force. buttressed to counteract outward forces. Gravity forces also countered by overlapping cladding and roof elements prevents water To eliminate bending, line of thrust must align with arch axis. into openings, gaps filled with silicon, concrete mortar. Dome structure is similar to a rotated arch. Forces in the dome are Forces: gravity, surface tension, momentum, air pressure differential. compressive at the top and tensile at the base. The domes forces are Flashing is impervious material preventing water from entering a structure from angle or outward at the base, may need to have bands placed around to prevent joint, placed over windows and roofs (sloped surface diverts water away). collapse. Use drip or breaks between surfaces to prevent water clinging to underside of windows, Shells – thin, curved plate like structures usually reinforced concrete. etc. Nullifies surface tension force. Shells transfer loads in the plane of their surfaces. Capillary breaks are complex shapes between inside and outside to prevent flow of water inside. Putting seal on inside creates air barrier and pressure equalisation chamber to prevent pumping of air from high to low pressure area. Heat is conducted through building envelope. Building is subjected to radiant heat. Thermal mass used to regulate flow of heat through building envelope. Thermal insulation reduces heat conduction. Thermal breaks (insulating materials) reduce heat transfer from outside to inside when using highly conductive materials. Double or triple glazing means more air space between glass, which reduces heat through elements. Buildings can have reflective materials, shading systems (outside). Thermal mass can be used to absorb heat and release heat when temperature drops (day and night). Materials: masonry, concrete, water bodies. Air leakage control is important for temperature regulation, principles same as water. Sarking (reflective foil) provides air barrier around doors and windows.
PAINTS
Clear paints – lacquers or varnishes. Oil based – prior to water based, good high gloss finish, not water soluble. Water based – more common, durable and flexible, water soluble. Properties vary with durability, colour consistency, gloss, flexibility.
GLOSSARY
Drip Downpipe Flashing Insulation Sealant Vapour barrier Gutter CHING Parapet
REFERENCE LIST