Stop batten for ventilation gap

[les_danger]

Stupid question here, but the AI response is garbled and annoying as hell.

I'm putting in rigid board insulation between the rafters of a pitched roof, and was going to put in stop battens to make sure the board doesn't go futher back and I can maintain a ventilation gap of 50mm. I only need something like 38x19mm as the boards should be a pretty tight friction fit on their own.

Shopping around for battens at the big stores - I can see 'green' pressure treated batten or kiln-dried (either sawn or par) options. These will sit outside of the thermal envelope but under the tiles and a membrane. Does that mean I should prioritise getting kiln-dried since the treated ones are mainly for outdoors?

 

[noseall]

Does that mean I should prioritise getting kiln-dried since the treated ones are mainly for outdoors?

No.

You just need to buy regular tanalised roofing (tile) batten. Either 19mm x 38mm, 25mm x 38mm or 25mm x 50mm.

It cares not whether it is indoors or out.

Is the membrane breathable?

 

[les_danger]

Thanks!

Yes the membrane is breathable, but the tiles are quite close fitting fibre cement that aren't counter battened. Hence still leaving the full 50mm. There is good ventilation from over fascia vents and ridge vents. When the wind is up i can see the membrane move like a bellows.

 

[^woody^]

Bang a couple of nails in

 

[noseall]

Bang a couple of nails in

Ok, but becomes a chore when doing small cuts.

 

[les_danger]

Thanks very much both, I really appreciate the input on small things like this that I waste a disproportionate amount of time over.

While i've got you, would you be able to offer an opinion on this - a few of the rafters have quite big shakes going all the way down them. This one is probably the worst, they're about 3mm wide and depth is up to 20mm. The rafter is only 50mm in width, so that's quite a chunk of it. I've had a re-roof recently so short of replacing is there anything that can be done? It's got me a bit nervous about nailing in the battens tbh.