100mm rock wool insulation is cheaper than 50mm can I use the 100mm in a 50mm cavity its for a summer house?
Answers:
The insulating quality of rock wool is based on the amount of air space between the fibers of the wool. If you stuff in twice as much wool, you will not have the proper air space and will not get the correct insulating quality.
Other answers:
If you only have a 50mm cavity, how do you expect to get in 100mm?
If you only have a 50mm cavity, how do you expect to get in 100mm?
I'm sure you could squash it in there, but then it would loose its insulating ability, or so I've been told.