The interior picture was taken on a property my client was considering. It shows the interior of a garage built using Rafters – probably built between 1940-1950. So I give it lots of credit for “standing out of habit” as a fellow Inspector would say. This very common type of roof framing is known a a Gable roof . The second image labels a more reliable method of construction when building with Rafters. You can see in the garage picture that ceiling joists (horizontal framing member) have been added (at some point) by a well-meaning ‘handy-man’ or ‘handy-woman’. But they are showing signs of failure under pressure, all of the ceiling joists are undersized and/or joined incorrectly.
Examples of Truss Designs (as compared to Rafters) Using Trusses allow much more flexibility in design but more stability (lol-pun intended). This is method of roof framing became popular after 1955.
It is possible to frame a Gable roof without including ceiling joists but there are additional framing components that must be utilized when you design/build a cathedral ceiling. This is because the weight of the roof (and any snow load) will cause the rafters to spread and a saggy roof line. Collars ties can also help to stabilize rafters, but they were missing from this structure.
Other framing methods that could (possibly) be effective to prevent Rafter spread:
–large structural ridge beams to connect rafters at the peak and large beams to transfer the load to the posts. (i.e. Cathedral ceilings) – This is a risky calculation for any ‘Week-end Warrior’ and even some skilled builders.
Modern construction will frequently be designed with Cathedral Ceiling but will utilize Trusses not Rafter systems.
-designs that include using a load-bearing center wall that extends from the ridge to the foundation.
-using large structural ridge beams to connect rafters at the peak and large beams to transfer the load to the posts. – This is a risky calculation for any ‘Week-end Warrior’ and even some skilled builders. But very common in new construction, giving us Cathedral Ceilings
– strong, reinforced wall corners (gable end walls to side walls) at all 4 corners. If the corners are held together the sides will stay together, hopefully. This too is risky by design.
If you are considering purchasing an older home, especially one that has been ‘updated’ please contact me. Improperly altered roof framing can lead to major defects that may not be apparent shortly after a remodel, sometimes taking several years (or major snow loads) to become obvious.