Knowledge base

Thermal resistance is one of three values that determine the thermal insulation of a building partition. Calculating thermal resistance requires knowledge of the lambda coefficient and the thickness of the material. Formula: R = d/λ, where d is the thickness in metres and λ is the thermal conductivity coefficient.

Thermal resistance R characterises a material of a specific thickness and is equal to the quotient of the material thickness and the thermal conductivity coefficient lambda. The unit of thermal resistance is (m²·K)/W. When selecting insulation material, thermal resistance R is more important than the lambda coefficient itself, as it takes into account the thickness of the material.

The heat transfer coefficient is a parameter indicating the amount of heat that flows through one square metre of a partition per second when there is a temperature difference of 1 K (Kelvin) between both sides of the partition. The unit of the heat transfer coefficient is W/(m²·K). Lambda λ is the thermal conductivity coefficient, i.e. the property of a material that determines its ability to conduct heat.

The standard dimensions of PIR boards manufactured at PCC Therm, without cladding and with aluminium cladding, are 1200 x 600 mm. The boards are manufactured in thicknesses ranging from 20 mm to 300 mm in 10 mm increments, as well as in thicknesses of 25, 35, 45, 55, 65, 75, 85 and 95 mm. It is also possible to manufacture boards in non-standard thicknesses and dimensions.

Compressive strength is a mechanical property of a material that characterises its ability to transfer compressive loads. It is the compressive stress at which the material deforms by a specified amount (usually 10% of the sample height). According to the standard, compressive strength is determined by compressing the sample in a direction parallel to the surface of the board (in the direction of thickness). Compressive strength should not be confused with compressive strength.