(1) Any opening which gives access to a roof-space in a sloping-roof assembly through a ceiling, or through a subdividing-wall in such roof-space, shall be fitted with a non-secured cover or door having a fire-resistance rating of not less than that of the ceiling in the roof assembly concerned.

(2) Such cover or door shall be so constructed that it will remain closed when not in use.

(3) The size of such opening shall be not greater than 1 × 1 metre and not less than 600× 750 millimetres.