Thread: What size rafters & battens?

G'day Mick,

if i remember correctly there is a standard however its state by state, i think you'd get a better answer over on the reno forums Renovate Forums.

Neal.

Thanks Neal. I'll try the renovate forums.

Mick

Originally Posted by 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?

Mick

I think your first step is to check with your local Government as to the requirements for obtaining a building licence and if they have any thing layed down on building on building Pergolas and or Leantoos.
They may require you to submit working drawing and specification accompanied with engineering calculations. Bare in mind wind loadings and conditions in your area.
Rule of thumb with a span of 3.5m I would have said that the rafters should be ex 175 x 50 sawn in hardwood and possibly 200 x 45 in structural pine. The rafters to be spaced at no more than 800 centres. Purlins ( batterns) should be ex 75 x 40 sawn or 70 x35 in Pine. The purlins to be spaced at max 900 centres.
If the rafters are less than the sizes above then you will find they will sag over the distance in time.
I hope this information may be of help.
Regards
Malcolm.