So our daughter's room is in the roof space and her room is frequently very cold. The stud walls are insulated with just 100mm of fibreglass. We plan on increasing this insulation using something like kingspan.
What i don't know is whether we can simply attach the kingspan to the stud wall over the top of the fibre glass or whether we need to remove the fibre glass and put the kingspan in between the verticals on the stud wall. What do people advise?