The fourth and last type of dwelling is the ideal fireproof house, but it is so costly that very few examples exist. This type can be termed fireproof with accuracy, for all structural parts, including doors, windows, and trim, are of incombustible materials. Metal trim is used or wood that has been treated to make it fire-resisting. This latter class of construction is so out of the reach of the average home-builder, on account of its cost, that its value cannot be thoroughly appreciated. Practically the only examples in existence are large mansions, built by wealthy clients. _Cost Does Not Indicate Fire-Resistance._—In this classification of buildings it would almost seem that the cost of a building indicated its fireproof qualities. This is not true, however. There are many expensive dwellings which are just as great fire-traps as the less expensive ones. In both cases the fire hazards are the same, if they are built of the same type of construction. In fact, we could build a $60,000 dwelling according to Type II, and also a $10,000 one according to Type II, and make the latter more fire-resisting than the former by using certain precautions of construction in which the spread of fire is retarded. Except in unusual cases, the construction of the ordinary dwelling will be either according to the first or second type, and any fire precautions that are desirable must be applicable to them. Most comparisons of relative costs are made between the dwellings included under these two types, and the difference will be mostly a difference in the kind of exterior walls used in the construction. In fact, if any comparisons are made between different kinds of buildings, as to their relative costs, it is essential that only one feature be made variable and that all others be kept the same. _The Question of Costs_ Ever since the closing of the war the problem of knowing the cost of the construction of the small house has been a very intricate one, and no sure estimates could be made, until the plans were completed and let out for bids. Previous to the war, when costs were somewhat stabilized, it was possible to predict with a reasonable amount of accuracy the cost of the dwelling when the plans were still only roughed in. In order to show the fluctuation in prices, an example of a seven-room frame house of Type I can be mentioned. This house was practically 30 by 34 feet, and had a cubical contents of about 29,100 cubic feet and an area of 2,640 square feet. In 1914 this house cost $5,529.00, but at the peak of prices in 1920 this house cost $12,815.00, which was an increase of 131 per cent. In the spring of 1922 this same house cost $9,502.00 to build, which was about 71 per cent over that of pre-war prices.