Bitumen roof - what wood to use for rafters and purlins?

pinksleepybear

Hi, I need to replace the roof on my chicken run. It's 2.6m by 3.8m so it will need about 7 sheets of onduline, each weighing 6.5kg. It will have a 10 degree slope along the width.

I've found loads of info about the spacing of the purlins and how much support is needed for the slope of the roof, but I don't know what kind of wood to use and how many rafters I would need to put in.

Can anyone help?

27col

Corrugated sheet materials don't really need rafters. Purlins will be sufficient to support them. Top, middle and bottom with an extra one if the length is more than 2 metres. Places like Wickes will have How to Do It leaflets, which will have the dimensions of support timbers in them. At the risk of being called flippant, you will not have much or indeed any choice of timber. Plain deal is what they sell in various dimensions.

capeverde

Info above is incorrect, with coroline or onduline at 10deg pitch you will need purlins or rafters with battens at maximum 300mm centres or the sheets will be sagging like an incontinent's underwear.

size of the timbers would depend on which way they were running, if it was 2.6m I would use 4x2 and if it was 3.8 Id use 6x2.