1920s house - no roofing felt under tiles. Planning to reinsulate at joist level plus add ThermaWrap foil (or equivalent) stapled to rafters for additional insulation but also to reduce general dust and dirt blowing in through tiles.
Have read elsewhere that foil wrap under tiles can lead to damp etc ....so is this a sensible plan (re-roofing with felt added is not an option) ?
Was assuming that gap between foli and tiles would be adequate for "ventilation".
All advice appreciated