Thermal Resistance Of Roofing Materials

The third factor that affects the energy efficiency of the roofing system is the thermal conductance of the roofing materials.

Thermal resistance of roofing materials.

Building insulation of course is what we are normally referring to when we say thermal insulating materials but in a commercial roof system the r values of other components such as underlayment cover boards and even some adhesives can often be included when calculating the total r value of the system. For example a characteristic of a heat sink. For instance if you have a material with an r value of 12 attached to another material with an r value of 3 then both materials combined have an r value of 15. Thermal insulated metal roofing sheets impact resistance for metal roof shed helps in reducing vibration caused by industrial activity.

R value has the units of m2k w. Most roofing membranes have high thermal conductance whatever gets into the membrane gets out just as fast. All products have what is called thermal resistance and the r value defines the speed any material or product will lose heat. Specific thermal resistance or thermal resistivity r.

As we said before the r value measures the thermal resistance of a material. Thermal resistance is a heat property and a measurement of a temperature difference by which an object or material resists a heat flow thermal resistance is the reciprocal of thermal conductance. Hour degf. C is known only when the k the thermal conductivity of a material is known.

C or thermal conductance of these materials is the reciprocal of the r value. It is common sense for insulating material to retain heat well and the r value is a measure of how good a product or material is at doing so. Thermal resistance is the reciprocal of thermal conductivity. If just metal sheets are used on the roof they often come up against difficulties in guaranteeing good walkability resistance.

K is the heat transmitted through a 1 inch thickness of homogenous material per square foot per hour when there is 1 degree of temperature change. If installed uncompressed in a 152 mm cavity e g some manufactured framing products it will retain its full thermal resistance value of 3 52 m 2 k w. K btu inch sq ft. Low thermal conductivity value of 0 038 0 041 w m k compressive strength in the range of 40 80 kpa which is sufficient for exposed roofing applications weight is in the range of 100 200 kg m 3.

Absolute thermal resistance r in kelvins per watt k w is a property of a particular component. To counteract this thermal insulation has been a part of roofing systems for many years.