Thanks everyone, for the help. John your site is a aladins cave of
information. Could i ask how do you arrive at the position of the Knee
Wall.

As i only have 8 rafters i was going to sister a furthur 150*50 to each
rafter, and tie them in at the top, to make a triangle. Could i get
away with 150*50, coudnt find any information on the web of the correct
size for this.


thanks

garry