Now, now Brad...

In Pillars of the Earth the church cathedral groin vault ceiling fall and killed a lot of the pilgrams. They fixed that problem, but then they added flying buttress's to fix wind load movement on the roof structure. So flying buttress's keep the top of the church cathedral from swaying in the wind, but if the roof framing timbers weren't attached to the outside walls, what keeps the roof framing from flying off the building in high winds? Weight of the roofing material?

Sim