thanks so much to everyone for the replies.
sorry about the delay in getting back, but you gave me a bunch of new tasks - mainly measuring, setting up a spreadsheet and planning the room next to it to get some economies of scale since the insulation's going to be so much more expensive than...
i have used the search but there doesn't seem to be a definitive answer.
i have an attic room (by original design) in a victorian house.
the roof was leaking so we had to take down all the lathe and plaster leaving the rafters exposed. the leak has now been repaired and i have to make...