The present invention relates to production method of a low-density thermal insulation board (1) which has mineral-based core and surfaces of which are coated with a gauze or net-like coating material (3, 4), and thermal insulation boards (1) which are produced by this method. It is possible by means of the inventive method to produce thermal insulation boards (1) such as an A1 class non-combustible thermal insulation board or an A1 class non-combustible insulated roof board without the need for using high-cost coating technique which is frequently used in the prior art, by shaping the expanded perlite between the lower coating material (3) or the upper coating material (4) on a belt conveyor (C) via organic binders continuously in an economic way.