Thermal Insulation as a 'U' Value

Thermal insulation values of doors expressed as a 'U'= W(m2)K should only be for the entire door, not the panel section or insulated lath, but the entire door, as detailed in the BSEN 12428-2000.

When specifying or buying doors you should always ask for a copy of the laboratory test certificate, that clearly expresses the insulation value of the entire door, not the transfer value across the insulated lath or insulated panel.

Most Insulated Sectional Overhead Doors with 40-42mm thick PUR/PIR foam filled panels, should be able to achieve a 'U' value in the region of 1 to 1.3W(m2)K and possibly better with additional sealing for an entire door of approximately 4mtr x 4mtr square. It has been reported that some companies may state values as low as .4 or .5 W(m2)K. This generally would be the transfer value across the panel as is irrelevant in determining the correct 'U' value for the entire door.

Similarly with regard to insulated roller shutter lath, the ‘U’ value as stated clearly in the BSEN 12428-2000, should be for the entire door, not the lath. Most manufacturers of insulated roller shutters should be able to achieve a 'U' value on a 4mtr x 4mtr door of approximately 4-4.5 W(m2)K. If you are quoted anything less ask to see the test certificate.


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