Large open spaces sometimes require greater clear spans than you can get with common framing details. In recent years, the use of engineered lumber, wood I-joists, and various types of prefabricated trusses have become standard practice in response to this need. But occasionally, specific design factors and site conditions rule out prefab engineered products — when, for instance, the bearing walls don't have enough capacity to carry the end loads from trusses or the roof configuration can't accommodate standard trusses. Also, on some jobs, it may not be practical to use a crane: Scheduling complications, rental cost, or difficult site access may make anything too heavy to be handled by two carpenters seem like a bad idea. In such cases, I sometimes
