In article ,
The Natural Philosopher wrote:
Both ridge and purlins only serve to stop the rafters moving sideways.
(Euler buckling etc,). They have very little structural effect beyond
that.

Perhaps you'd explain why my loft conversion involved the fitting of steel
purlins if they have so little work to do?

--
*When everything's coming your way, you're in the wrong lane *

Dave Plowman London SW
To e-mail, change noise into sound.