I've recently bought a 1930s house and looking in the loft space there's no felt lining. You can see the backside of the tiles from the inside. What would be the best way to achieve some sort of insulation / roof protection without having to remove the roof tiles? For example is there a spray-on product that creates the same effect as felt?
I'm trying to find the simplest way of bringing the roof into the present day without having to remove the tiles.
Any advice would be wonderful!