At the opposite end of the rooms a similar opening is provided. For closing it a slightly different plan is adopted. The outer section is divided into doors five or six feet high, swung on hinges; these take the place of the weather boarding. The interior wall is then arranged the same as the one at the opposite end of the room. These doors can be opened as the ice is coming out, and remain closed at other times.
Interior partition walls are sometimes of value. It is thought they add to the durability of the house, and also effect a saving in wastage. In the majority of houses they are dispensed with.
The construction of the roof will be found convenient and substantial, if the plans shown in Plate [B] are followed. Light-colored roofing composition should be used, avoiding tar and gravel, or tin, as these both attract and absorb the heat. Gable roofs, with good shingles laid four or five inches to the weather, are the best roofs for ice houses. They are cooler and more durable than most composition coverings.
The posts in [Diagram B] can be extended and additional bracing put in. The increased area and weight will require a proportional addition to the strength of roof timbers. In the sizes of timbers for ice house construction, noted in this chapter, consideration has been given to durability, and while lighter material is employed, in some instances, the houses are sooner racked and sprung out of place.
FIG. 50. PLATE C. SECTION OF ELEVATOR INCLINE AND PLATFORM CONVEYORS.
The ventilator on top is about twenty feet square and two feet high, with slats on all sides. It will not be required on high gable roofs, an opening in each gable end being sufficient to carry off the moisture and heated air. The gable ends should be well braced against the wind.
At the center of roof trusses a floor is laid through the building, dividing the space above the ice. Trap doors are cut through this floor about seventy-five feet apart, four to six feet in size; these doors are for ventilating the space between the ice and the floor, and for dumping the sawdust through on top of the ice. It also affords a convenient place in which the sawdust can be stored and dried, when the houses are cleaned in the fall.
The outer circulating air-spaces are continued to the level of the loft floor, discharging the air into the loft, where it finds vent through the ventilator.
The eaves project about two feet, and are provided with ample gutters, which are furnished with large conductor pipes every fifty feet. On the side of the house where galleries are placed, the roof is extended to cover them, or, if at a gable end, a special roof is provided.