If you intend to use the loft for storage then the most cost effective solution is a cold roof where the insulation is laid on top of the ceilings of the rooms below.
Insulating a tiled roof.
It s worth insulating the sloping insides of a pitched roof in order to conserve heat if the space is to be used for anything except simple storage.
The original insulation plan from the insulation contractor was to insulate the roofline.
Roof tile insulation is primarily used to protect your roof against the elements and reduce heat loss.
Under roof tile spray foam insulation acts to add a barrier between the inside of your home and the harsher outside protecting your property and providing significant long term benefits.
This is usually done by laying quilts or batts of insulation between and over the joists.
Install baffles on the underside of the roof sheathing net and blow cellulose into the rafter bays cover that with 2 rigid foam.
The main difference between the two is the location of the insulation.
The water situation made us think that is a bad idea.
The main decision to make when insulating a pitched roof is if you are going to have a warm roof or a cold roof.
This will depend on the construction on your roof and if it is a refurbishment whether the roof tiles are going to be removed.