Hello, I want to put more insulation in my loft, there is currently some between the joists (100-150mm or so). I have a combi boiler in the loft so hot, cold and gas pipes run over the existing insulation on top of the joists. These pipes are already lagged with foam insulation. My question is: Can I roll 200mm thick glass mineral wool insulation directly over the pipes without risk of 'over' insulating them or causing another issue? Many thanks - am a reasonably proficient diyer, but never used loft insulation or had a boiler in the loft before. Cheers, Marshy.