I would like to improve the insulation in the attic of the second hand home I have recently bought. Currently it has a layer of blown in insulation 'bits'. Would it be possible to put insulation rolls on top of this or will I have to blow in more 'bits'?
You can roll out mineral wool or glass wool insulation over the ceiling joists. 150 mm would be a good size. If the void in the joists has some space you can get 25mm, 50mm or other to fill any remaining height.
Remember to lift any wiring above the insulation where at all possible.