On Mon, 1 Sep 2008 15:12:11 -0700 (PDT), a particular chimpanzee,
robgraham , wrote:

Can someone give me some guidance on what timber size I should use for
a felt roof with the following measurements :-
Span - 2.5m
Length - 4m
Angle - nominally 10 degrees
Covering - Sterling board and felt + insulation.

I'm assuming 600mm between centres.

Assuming access for maintenance only, and assuming you're at less than
100m above sea level:

At 600mm C/C: 38mm x 147mm C16, 63mm x 122mm C16, or 47mm x 122mm C24.

At 400mm C/C, 47mm x 122mm C16's will span 2.48m.
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