My loft is insulated with 4 inches of insulation and and floored with chipboard and used for storage. Will I save much money on my heating if I just lay glass fibre insulation on top of the flooring where there is nothing stored or will the costs outweigh the savings. At present my heating goes off about 10pm at night and comes on again at 8am but the temperature upstairs never falls below about 15 degrees centigrade during the night even although, for example, last night the outside temperature fell to minus 3 degrees centigrade.
I had already replaced the loose fill 2inches of loft insulation (I suppose it was 4 inches when the house was built) with rolls of glass fibre when I floored the loft a few years ago and this made a significant difference to my heating bill but I was wondering if what I propose would make a large or small difference?
My house is double glazed throughout and although not cavity wall insulated the walls have insulated plasterboard on the inside, it was built in the early 1990's.
Thanks for any input, Jan