What size timber for Yorkshire boarding?

[Kidds]

I want to enclose my shed with Yorkshire boarding.
It will be no more than 2.4m height and 15' bays.
What size timber for the purlins (if that is what they are called)?

 

[Fendt516profi]

7x3

 

[Mur Huwcun]

What’s the eaves beam or top timber? If that’s substantial enough then 4x3 will do as perlins and support the centres from top down

 

[Skintagain]

I like to bolt a 7x3 in upright for the bottom purlin stops them sagging some fair weight in 30 wet boards

 

[Kidds]

What’s the eaves beam or top timber? If that’s substantial enough then 4x3 will do as perlins and support the centres from top down

steel beam

 

[Mur Huwcun]

steel beam

Can you bolt a tomber perlin into or onto it in right position to take the boards?

 

[Kidds]

Can you bolt a tomber perlin into or onto it in right position to take the boards?

I have been looking at exactly that this morning and yes I can.