Learn how a roof badly constructed can affect you.
And how a badly constructed roof can be fixed. QBIS.
No supporting prop to end of an under-purlin (horizontal beam fitted to midway point between the external wall and peak of the roof).
This can be supported with a beam supported off the external wall plate that extends towards the ridge with a prop off an internal wall.
How joints of under-pulin props should be supported.
Good example of correct method of support. Without proper support of a roof structure the risk of considerable sagging or potential for collapse is increased.
Badly constructed roof. Another poor example of how an under-purlin should not be supported.
These are examples of how important it is for building inspectors to physically climb within a roof, otherwise this potential danger (but easily rectifiable fault) would be missed in their inspection and become a buyers problem to have fixed.