Wendelspanswick
Member
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Planning on doing the roof on the barn next month and trying to work out the best way.
We have to use plain box profile sheeting as that is what we stipulated on the PN, although I do plan to clad the roof with sawn timber shingles over the box profile at some stage in the future.
I have built the roof to have 9x3" purlins on 1200mm centres, the plan is to put 18mm OSB over the purlins, with a breather membrane on top of that and then the box profile.
The OSB is to reduce rain noise and to stop the membrane 'pooling' on the purlins.
Once the roof is done I will insulate from underneath between the purlins.
Questions I have are -
I guess I need a few rafters, to stop the OSB sagging?
And do I need an air gap between the box profile and the breather membrane?
And before anyone mentions building regs, SAP calculations or U values this is an agricultural building so needs none of the above.
We have to use plain box profile sheeting as that is what we stipulated on the PN, although I do plan to clad the roof with sawn timber shingles over the box profile at some stage in the future.
I have built the roof to have 9x3" purlins on 1200mm centres, the plan is to put 18mm OSB over the purlins, with a breather membrane on top of that and then the box profile.
The OSB is to reduce rain noise and to stop the membrane 'pooling' on the purlins.
Once the roof is done I will insulate from underneath between the purlins.
Questions I have are -
I guess I need a few rafters, to stop the OSB sagging?
And do I need an air gap between the box profile and the breather membrane?
And before anyone mentions building regs, SAP calculations or U values this is an agricultural building so needs none of the above.