New roof on windy site

[gasmanuk]

I own an edwardian property which is right on the coast and has rooms in the roof space. We intend to re-roof the property but would like to make the roof as airtight as possible. What is the best way to achieve this and don't know whether insulation board above the rafters works well and am not convinced with tri-iso but I don't really know about either. The main thing is to insulate it as much as we can. The roof is slate by the way.

Thanks

 

[masona]

would like to make the roof as airtight as possible.

Air tight: do you mean so the high wind won't blow the tiles off or to stop draught coming into the roof area?

Just re-read your post:

My opinion is to do close boarding such as exterior plywood sheet onto the rafters then roofing felt + battens + tiles (I would nail every single tile if you live near the coast or high wind area). I would use 50mm insulation slabs on 100mm rafters leaving 50mm air flow gap with soffit vent at the bottom and ridge tile vent at the top giving circulation of air flow then plasterboards on the inside, if it's already plasterboard then the insulation would to be put in first before tiling etc.