Sheet of insulating plates and its use

A sheet of insulating plates comprising successively placed several lamellae of insulating plates attached to each other at their edge side which is cross directional in relation to a longitudinal direction of the sheet of insulating plates, alternately at upper corners and lower corners of the cross directional edge sides, whereby thus formed uniform sheet of insulating plates comprising the several lamellae of insulating plates is capable of being foldable into an accordion-like folded stack of the several lamellae of insulating plates and unfoldable into the uniform sheet of insulating plates, which sheet of insulating plates has an upper surface and a lower surface, wherein the upper surface of the sheet of insulating plates comprises a surface layer which is arranged in the longitudinal direction of the sheet of insulating plates alternately attached to and detached from the several lamellae of the insulating plates in groups of two successive lamellae of insulating plates, wherein the insulating plates are formed of a heat insulating material.