My house is small with a small loft in the center part only, as the outer roof is used within the front and back rooms. It is already insulated in the loft and roof to an epc C directly behind the roof tiles ( images attached ). I wish to board the loft area for extra storage. The area is around 11m2 and the joists are 90mm x 40mm.
1. Given there is already insulation should I add to it by putting some under the loft boarding? If so, how much ?
2. As the joists are only 90mm deep, what is the acceptable most economic method for raising the floor ( if I have too depending on your answer in 1 ) ?
3. As I have halogen lights, I read I need to use the "loft lid" around them. Can I put some insulation around the loft lid and board over them?
As I'm new to DIY if anyone can offer some good advice it would be much appreciated! Thank you!