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Insulation performs two functions in a roofing assembly. The obvious use is its role in

reducing the heating and cooling loads on the structure. The second and certainly every

bit as important use is its function as a substrate to support the roofing membrane. In an

inverted membrane assembly, the insulation is a substrate for the ballast and a protection

layer for the membrane. There are numerous roofing insulation products on the market

and as with all material products, the various insulations have their advantages and



The insulating value of a material is measured in terms of its"R" or"RSI" value R

being a value in imperial measurement and RSI being its metric equivalent. RSI or R

-value is a measure of a materials ability to restrict the transmission of heat and is stated

relative to the thickness of the material


The second property of insulation, its role as a substrate, is much harder to quantify

This property has many components and unfortunately for some insulation

manufacturers, the true ability of their product to perform in the role only becomes evident after several years of service. Insulation must be mechanically stable to prevent

curling and shrinking and must be strong enough to support traffic loads

insulation Properties


The properties that insulation should possess, especially if it is to be used in an exposed

membrane, warm deck roofing system are:



  • High resistance to heat flow -to reduce heat losses from the building(high"R

  • use)

  • Dimensional stability -to minimize volumetric change due to variations in temperature and moisture content. Lightweight- to minimize dead loads(loads due to the weight of structure). Shear strength -to resist deformation.

  • Impact resistance -to provide a stiff support for the membrane and resistance against indentation or puncturing

  • Durability- especially with regard to moisture(wetting and drying) and thermal cycling

  • Fire resistance-to meet Building Code requirements

  • Chemical stability -to minimize future problems with curing

  • Compatibility with other materials used in the roofing assembly

  • Surface smoothness- to provide a satisfactory surface for application of the membrane.

  • Compressive strength- to resist traffic.


Roof Insulation Installation Service in Ottawa

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