When it has been decided to build an iyacaskuni all the young men of the neighborhood join in the labor while some of the older men direct them in the prescribed methods. The procedure is much the same as that employed in building the regular hogan, but larger timbers are required. Any kind of timber growing in the vicinity is used; but as groves of pinon and juniper are most abundant in the Navaho country, these are the kinds usually employed. The stunted, twisted trunks of these trees make it a matter of some difficulty to find the necessary timbers of sufficient size, for they must be at least a foot in diameter. When found, the trees are cut down and carried to the site selected, which must have fairly level surroundings, free from dense wood and underbrush, so as to afford a clear space for the ceremonial processions and dances. Four heavy posts are necessary—“legs,” the Navaho call them—and these must be trimmed so as to leave a strong fork at the top of each at least 6 feet from the ground when set upright. Four others, for the horizontal roof-beams, must be 10 feet long, but without forks; and two more, the straightest and longest, are necessary for the doorway passage. These ten timbers are called tsaci, the same term that is applied to the five main timbers of the ordinary hogan.
The four posts are set firmly in the ground in shallow holes at distances apart corresponding to the length of the main roof-beams, and so arranged as to describe a square, the sides of which face the cardinal points. The prescribed position of the doorway is the center of the eastern side, and it must face the east exactly. The post at the southeastern corner is the first to be set, then the one at the southwestern corner, with the forks arranged on the same line. The northwestern post is then set, and finally the one at the northeastern corner, and the forks of the last two are also placed on the same line. In the ground plan (figure 241) the posts are numbered in the order in which they are set up. This sequence is not always strictly followed, but the old men say that this is the proper way.
The beam for the southern side of the roof is next lifted into place and laid so as to rest in the forks of the two posts on that side, with the ends projecting a little beyond them. The beam on the northern side is similarly placed, and the western and the eastern beams are next laid so that their ends rest upon the ends of the beams already in place. Another timber is then placed parallel with the eastern beam, as shown on the plan. This forms the western side of the smoke-hole and also a support for the smaller roof-timbers to rest upon. Sometimes an additional timber is laid across for this purpose between the one last named and the next beam. The two timbers for the sides of the doorway passage are then placed in position about 3 feet apart and leaning against the eastern roof-beam. The butt ends rest upon the ground, and the space between them should be in the center of the eastern side. All the main posts and beams are stripped of bark, the rough knobs and protuberances are hewn off, and they are finished according to the skill of the builders or the exactions of the old men who superintend the construction.