Section 25. No salamander or stove for drying any construction material shall be used in any building except under such conditions as may be prescribed by the board; and no such salamander or stove shall be set upon a wooden floor unless it is raised above the floor at least four inches and set upon brick or other incombustible material in a bed of sand at least two inches thick, spread upon the floor and covering an area of at least two feet in all directions larger than the area of the salamander or stove.