Heat Insulation And Vapour Barriers

An Insulated Wall Frame


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Residential heat loss is reduced by thermal insulation. The insulation R value, or resistance to heat flow, depends generally on the amount of air trapped in tiny spaces within the insulation. Good insulators have high R values. Many kinds of thermal insulation also reduce sound transmission and are fire resistant. Loose fill insulation, such as rock or fibreglass wool, wood fibre, shredded bark, cord, vermiculite, and perlite, are put into attics over vapour barriers and into the side walls of an uninsulated older homes. It is either transported in bags or blown into its location by a pressurized hose. Flexible insulation, such as mineral wool batts and blankets, have widths suitable for stud and joist spacings. They are placed into walls, ceilings and floors. A vapour barrier is placed on the warm interior side of the insulation to keep the air's water vapour from condensing in the cooler exterior walls. Rigid insulation panels and tiles are made out of vegetable and wood fibre, polyurethane and polystyrene foam, and fibreglass, and are used on walls, floors, roofs and ceilings. Structural rigid insulation is used to sheath and insulate external wall frames, and nonstructural rigid insulation is used to insulate foundations, walls and roofs. Reflective insulation, such as aluminum foil sheeting, reflects the heat back to its source. It is often placed on the warm side of batt or blanket insulation where it also acts as a vapour barrier. Foamed-in-place insulation is a chemical foam that is poured, sprayed or blown into wall cavities. It is put into the open walls of newer buildings, into the walls of older uninsulated buildings through small holes that are later plugged, and into the cavities of masonary walls after removing individual blocks that are later replaced.
                                         



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Written and maintained by
Ronald Hunter
           
  All images and text are copyright Ronald Hunter 2005 to 2011.
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