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