There you go then ... the longer ur in the game the more you'll see- especially the small ones where theyre not desighned......pre TG 20 most of the smaller companies would rely on their experianced and long served scaffolders to just get on and do it, unfortunatly this may technically not be allowed anymore but tbh most basic roof structures follow the same method of erecting, so once you know what ur doin theres hardly ever a problem....up untill the need for desighn i,d never heard of the terms such as kentledge or uplift but all our roofs with common sense had plenty in them to allow gor the unforseen dangers of bad weather......but nowadays its not uncommon to see a small semi with some ali beams thrown back to front with no bracing or ties/ kenteledge & just the mattress on top.
I often look at these and cringe, its an accident just waiting to happen