I'm helping a mate insulate his roof. It's possible to see the tiles as there's no felt under them.
The top loft is lined with some form of brown paper and then there's a section of tile/joist/sloping ceiling that is cold and at the bottom is a crawl space in the eaves at 1st floor level that is just tiles.
there's a horrible draught runs through the bedroom floor space and up through the boards. To say it's well ventillated is an understatement.
What we propose is to add rockwool slabs in the traditional Loft and maybe board it as well.
We wondered if trying to slide Tyvek type fabric down the sloping section maybe followed by either rockwool or the thin bubble/foil insulation would be ok?
in the crawl space we'd use more tyvek and rockwool. Also, would placing rockwool in the first floor gaps in the manner of an air filter prevent the cross draughts without compriomising ventilation?
Not talking lifting all the boards - just filling the gaps in the crawl spaces to block draughts.