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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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