Advice need Lean to roof

[FO21]

Hi,
I would really appreciate some advice regarding a lean to roof. I'm currently building an extension to the back of my house (4.4 x 4.6) with a lean to pitched roof (concrete tiles).

Looking at the timber specifications the 4.7 slope (17.5 degrees) is greater than the largest span of 50x150 with 400 centres is 3.78m. The other issue is that the width the extension is greater than the largest span of a purlin 75x225 with a 3m spacing is 2.68.

Is the only option a brick pier in the middle of the room or a steel RSJ to support the rafters?

Appreciate your time!

 

[bobsuerita]

or go with 225x 47 c24 @400cc

 

[FO21]

Thanks for the quick response! Does that mean the up rated rafters 225x47 will cover the entire roof span?