garage rafter size

[ferguson1947]

building new lean to garage new rafters will be 4.8m long fastened to existing wall at the top and onto a wall plate on top of a 6 inch wall at the bottom the roof will be box profile sheeting
the existing wall is a neighbours 2 story extension and it is in an enclosed area
what size rafters and spacing do u recommend timber or steel

 

[ferguson1947]

can I brace the rafters at the top about a metre down the rafter and wall still to maximise height and at about 500mm at the bottom near propose workbench

 

[tony1851]

what size rafters and spacing do u recommend timber or steel

If timber 8x2 (ish?) @ 400c/s.