The second type is an arched vault made of wooden elements that are steamed or boiled in special metal forms. It is placed in this form, with the addition of hot water and, maintaining boiling, leave it to evaporate for several minutes. After that, in order for this design to acquire the desired shape, it creates a mechanical stress in the places of bends. For this purpose, devices are used, such as pipeline machines that fix the wooden element until it dries completely.
The third species is a wooden block on which wood is glued with thin stripes, in convex places. Such multi -layer gluing can give a wooden arch a variety of forms.