# Forum Home Renovation Structural Renovation  Rafter & Batten sizes . Am I on the right tracK?

## Glider

I am rebuilding a lean-to and wondering if I have selected the right timber sizes. It will be 6000mm long and have a single span of 3500mm with colorbond roofing. I think the rafters should be 140 x 45 with 900mm spacing & the battens 70 x 35 spaced at 600mm. Does anyone know if this will conform to the Aust Standard? I have looked at the span tables but don't fully understand them.  :Confused:  
Any advice would be greatly appreciated. 
Mick  :Smilie:

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## r3nov8or

Just to be clear, this will be 6000mm parallel with the existing wall and come out from the wall 3500mm? Yes? 
Rafters - If the above is correct 140x45 is OK for a metal roof with no ceiling lining. You'll need 170x45 for metal roof and ceiling lining. 
Battens - Timber Solutions suggests 35x70 will span 850mm (this surprised me as I was thinking 900mm was OK). Anyway, if you space them at 550mm Timber Solutions says 35x70 is OK, or keep your 600 spacing and use 35x90 instead.  
All based on seasoned pine F7 grade. 
What will hold up the new roof - a new wall or posts? I'm assuming a wall because you haven't specified a beam to hold up the rafters.

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## Glider

> Just to be clear, this will be 6000mm parallel with the existing wall and come out from the wall 3500mm? Yes? 
> All based on seasoned pine F7 grade. 
> What will hold up the new roof - a new wall or posts? I'm assuming a wall because you haven't specified a beam to hold up the rafters.

  The layout is correct and I had planned to use F7 structural pine with no ceiling lining. The new blue board cladded wall will sit on the slab (100mm with 82 steel) and I had planned to use 90 x 45 F7 studs at 450centres  with 90 x 90 F7 at each end. The beam under the rafters had been planned as 90 x 45 F7 and the wall braced with 20-25mm gal strap (?) in a single V configuration. 
I am now thinking that the rafter supporting beam may be too weak. 
Mick

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## r3nov8or

The new wall's top plate (aka "rafter supporting beam") at 45x90 with 90x45 studs at 450 centres is fine. 
Plan to place your rafters on the top plate directly above a wall stud. Should be easy with studs at 450c and rafters at 900c

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## Glider

Thanks for your advice r3nov8r! Much appreciated. 
Mick

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