The last of the interior fittings to be applied are usually the doors. These are of two classes, "stock" doors and doors made to order. Stock doors are made in certain regular sizes, generally of pine, whitewood or cypress, and may be obtained at all times, of the dealers. Stock doors are made in three grades, A, B, and C, of which, doors of the first quality may be used for the inferior portions of good houses, but these, by reason of their being stored for a greater or less time, are generally not thoroughly dry and will shrink and twist when subjected to furnace heat. The second and third quality of stock doors are a very inferior article and should be used only for the poorest kind of work.