Home Insulation
Introduction The purpose of insulation is to slow down the rate of heat exchange from one environment to another. Cold air outside the house will eventually make the inside of the house cold too unless the house is heated from within. The reverse is also true – hot air outside the house may raise the inside temperature without air conditioning. A good illustration of the purpose of insulation is a home where the furnace is off on a cold winter night – a home which has no insulation will freeze within a few short hours but one which is insulated may take many more hours. Insulation does not keep the house warm or cold it just slows down the rate at which it would normally take to change. This resistance to heat/cold transfer is referred to as an R value for insulation materials. In new homes a typical exterior wall will have R20 insulation but in the roof, where most heat escapes, it may be at R40. The R value is in general use across North America but the Canadian federal government uses the metric system and it is referred as RSI factor. Rigid Batts Loose
Return to top	External Rigid Insulation Insulation sheets of polystyrene or similar lightweight material measuring 4 feet X 8 feet may be added to the exterior sheathing on some properties. It is easily cut to shape and may then be covered with siding. In house construction it is common to see this form of insulation glued to the foundation wall and extending to the footing.
Return to top	Exterior Insulation Fibreglass insulation generally comes in “batts” which are 4’ long and 15” wide. They are tucked into the space between the studs and then covered over with a plastic (mylar) sheet vapor barrier followed by the interior gyproc sheets.
Return to top	Installing Insulation The batts are held in place as they are an exact fit for width and may be cut to any size when necessary. The glass fibres from most insulation can irritate the skin and cause breathing difficulties.
Return to top	Roof Insulation In most new construction the space between the trusses is filled with double layered glass fibre insulation batts but sometimes it may be “blown in” and is called “loose fill”. This is more common when “retrofitting” older homes with insulation.
Return to top	Other “Blown In” Insulation Products other than glass fibre have been used for insulating houses including vermiculite, cellulose, mineral wool and even reflective foil. Old ideas of newspaper, seaweed and hay are not considered practical because of their low rating and fire hazard. Some insulation products have been considered a possible health hazard.
Return to top	Sprayed-on Insulation An alternative method of installing insulation includes spray-on products which can fill spaces more precisely than batts and those which expand when exposed to the air.

 

 

 

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