Experience has shown that the two widths--18 feet and 26 feet are peculiarly adaptable to the dimensions of the various farm machines. Using the 26-foot width, considerable opportunity is given for the utilization of the floor space, since a wider floor area unsupported by posts is available. As far as possible, interior posts should be avoided, for they interfere very seriously in the placing and moving of machinery. =The Two-Story Type.= As stated before, the use of a two-story machine shed is rather rare, for two reasons: First, the additional expense in material and labor, and, Second, the difficulty of getting machines up to the second floor. The only advantage that is gained is the doubling of the floor space under the same roof. [Illustration: Fig. 13. Details of Two-Story Implement Shed The framing in this type of shed must be unusually strong and substantial. The girders and, in fact, all framing members, may be either solid or built up. A central post is necessary in each framing unit.] The construction of the building (illustrated in Figs. 13, 14 and 15) will necessarily be rather substantial. The framing may consist of 6x6 posts and 4x6 girts, which should be securely joined in order to give rigidity to the structure. The girts are located at vertical intervals of not to exceed 5 feet, so as to afford good nailing for vertical siding. If horizontal siding is used, the girts may be spaced wider, say, one each at the top, bottom, and middle of the post, while 2x6 studs are set in on which to nail the boards. Diagonal bracing is a decided advantage. The building may be constructed either 18 or 26 feet wide, and it is seldom that a building longer than 40 feet will be necessary. The foundation should be much more substantial than in the types previously described. It should extend well below the frost line and be almost as strong as that used for barns.