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.

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. The thermal resistance of unit area of a material is measured by the r value. Hour degf. If just metal sheets are used on the roof they often come up against difficulties in guaranteeing good walkability resistance.

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. All products have what is called thermal resistance and the r value defines the speed any material or product will lose heat. The r value is proportional to the thickness of the products or material. Thermal insulated metal roofing sheets impact resistance for metal roof shed helps in reducing vibration caused by industrial activity.

Most roofing membranes have high thermal conductance whatever gets into the membrane gets out just as fast. 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. 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. Thermal resistance is the reciprocal of thermal conductivity.

Absolute thermal resistance r in kelvins per watt k w is a property of a particular component. 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. Specific thermal resistance or thermal resistivity r. C or thermal conductance of these materials is the reciprocal of the r value.

K btu inch sq ft. 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. As we said before the r value measures the thermal resistance of a material. R value has the units of m2k w.

C is known only when the k the thermal conductivity of a material is known. For example a characteristic of a heat sink.