2. _The use of the sill_, because it serves as a firm foundation for the outside studs and first tier of floor-joists. The balloon-frame has no sill, for the floor-joists are set directly upon the top of the foundation-wall, and the exterior studs are built on top of them. 3. _The use of the corner braces_, because they stiffen the frame. [Illustration: TYPICAL FRAMING OF “WAR HOUSES.”] FEATURES OF THE BALLOON-FRAME WHICH HAVE PERSISTED 1. _The use of small timbers_, or the standardization of the 2 by 4 for all parts except the sill, because of economy. The corner-posts are made of three 2 by 4’s, and the plate is made of two 2 by 4’s. 2. _The use of the nailed joint_, because of its cheapness and its greater strength. It will not rattle loose when the timber seasons, as does the mortise and tenon joint in the braced-frame. 3. _The use of the ribbon-board_, in place of the girt, for those houses which are to be stuccoed, and a rigid, outside wall-frame is desired from sill to plate. 4. _The use of diagonal sheathing-boards_, to brace the frame instead of the corner-pieces. The reasons for this are not very certain, since diagonal bracing with sheathing is not always effective, while it is extremely wasteful. The combination-frame includes all of the present-day methods which make use of selected features of both the braced-frame and balloon-frame, such as were noted above. There are no rules to follow. In certain sections of the country one type is favored more than the other. Where a house is to be covered with stucco, the balloon-frame is a better type to use than the braced-frame, since it gives a stiffer outside wall as a backing for the stucco. _Platform-Frame_ [Illustration: PLATFORM FRAME] It will be noticed in the illustration how different is the amount of cross-section of wood in exterior and interior walls of the combination-frame, a thing which causes the unequal settlement previously alluded to. In order to reduce this to a minimum, it is often specified that the studs of all interior partitions be carried down to the top of the cap of the partition below or to the top of the supporting girder, thus reducing the amount of cross-section timber. This is not a complete cure, however, although it is a big improvement.