BURNT BOARD

PROBLEM TO BE SOLVED: To provide a burnt board which is not deformed by gravity in the case of burning to prevent strains from occurring therein, in spite of a thin board having a means for locking the board which is not yet fixed in the case roofing work is carried out. SOLUTION: In plate-like burnt boards coating roof slope or building wall surface by successively being roofed while overlapping them, a plurality of projection threads 2 are provided to one or the other of the rear end side on the upper surface for each of the said burnt boards and the front end side on the lower surface, a plurality of recessed grooves 3 are provided to the other, and they are provided in parallel with both in front and in the rear. In the case of roofing, the said recessed grooves 3 or the projection threads 2 are fitted to projection threads or recessed grooves of the other board located both in front and in the rear, and the recessed grooves 3 end halway on the beginning surface from the end of the board.