Screwing slates to battens

[vinn]

I wrote "Screwing down slates is rarely done except for very particular circumstances" and "I've only used screws for particular purposes".

AAMOI: I've never "worked on a roof with thin rafters and a delicate plaster ceiling".
But my above quotes indicate that I would use screws if the site situation called for them.

So what the purpose of your question is I dont know?

 

[vinty]

I think that’s a very fair point…

The chances of making my loft air tight, must be next to non existent !

I’m sure that things will improve, wrt to drafts, when the slates are all positioned correctly – but simply, the building has too many imperfections, for there to be no air flow.

Provided he can work out the placement of the eave slates – and has calculated the headlap correctly, I’m now optimistic that it all will work out OK !! (I’m a glass half full kind of guy )

I believe the formula for working out the length of eave slates is gauge+headlap , if the length of slate is 24" and the headlap is 4",so length of slate minus headlap =20"÷2=10" which is gauge for battens so gauge10"+headlap4" =14" for eaves slate.
I think the eave slates fall 2" into the gutter.