The box gutter of a roof is parallel from end to end, and has upright (instead of sloping) sides, the latter being formed by the pole plates on which the bottom ends of the common rafters rest. A box gutter may be between the pole plate and a parapet wall, or between two roofs sloping to a gutter between them. The ends of the bearers for the sole of the gutter are housed into the pole plate for an inside gutter, and one end into the pole plate and the other resting or notched into a wall plate when the gutter is next to a parapet wall. Such gutters should be not less than 1 ft. wide, so that a person can walk in them without stumbling or treading on the eases of the slates. The fall of the gutter should be about 2 in. in 10 ft., and the drips should be not less than 2 in. deep.