It is as important to know how to properly put up the frame work of a roof as it is to know how to lay it off correctly. First see that the plates are straight and the angles true, then set up the deck or ridge on stanchions the proper hight ; next put up all the common rafters which will not interfere with hips and valleys. Many mechanics advocate raising the hips and valleys first, but practical experience will prove that this is a great mistake. Put up first all the common rafters that can be raised conveniently. There is always a ready way to plumb a pair of common rafters, and if the common rafters are plumb they will square up the roof ready for hips and valleys, which, being on an angle with the plates, are often very bothersome to set to the required angle. They are also troublesome to plumb up, especially when they are the first rafters raised. By raising the common rafters first the deck or ridge is brought into the proper position for the hips and valleys and the trouble of squaring and plumbing the hips and valleys is much less. After raising the hips and valleys stay them straight and finally put in the jacks, being careful not to spring the hips and valleys when nailing the jacks.