Additional Loft Insulation - Lose old?

[DIYDisaster987]

Hi,
My house was built about 35 years ago and has about 100mm of insulation between the joists in the loft.

For obvious reasons I want to increase this and am aware 170mm at 90 degrees to joists is way to go.

My question is should I replace the old insulation with new 100mm before adding the extra 170mm on top? It's all pretty compressed and probably not doing much. Or should I lay an extra 100mm over the top?

Any recomendations for a cheap and simple system for supporting a floor above it for storage would be welcome!

 

[Mike_Romeo]

Similar issue here, 1970s house. Around 100mm of old insulation has been added at some point over the years but been tossed around and moved that much that it's in bad shape. I have removed some of it and replaced with new Knauf loftroll, 100mm between the joists followed by 200mm laid perpendicular on top. Loft lids stuck down covering any downlights.

Some will say removing the old is un-necessary, but it was awful to handle and trying to fix it back into position properly was going to be more difficult than bagging it. Awful irritating stuff too so if you do remove it, mask up, googles and even one of the cheap disposable white suits.