Method and structure for constructing upper board fixed on bottom using square timber

A structure for constructing a floor-fixing type upper plate using a square timber and a construction method of the same are provided to preclude the motion and prevent the curling of the upper plate by fixing the molding material with the concrete tacker pin or the concrete nail. A structure for constructing a floor-fixing type upper plate using a square timber is composed of an insulating material(20) installed on a floor(10); a square timber(60) mounted between the insulating materials and directly fixed at the floor; a side molding material(70) installed between the insulating material and a wall(W) and directly fixed at the floor; a heat radiating body(30) mounted at the upper part of the insulating material to use the hot water as a heat source; and an upper plate(40) laminated on the heat radiating body and fixed at the square timber and the side molding material. The square timber and the side molding material are fixed at the floor with the concrete tacker pin or the concrete nail when the floor is the concrete slab or the mortar layer.