Insulation in rafters

[WhiteChristmas]

Hi, I know similar questions have been asked before but I haven't found an exact answer so wonder if anyone can help.

I live in a (approx) 1935, 3 bed semi. There is no felt behind the tiles so it is quite draughty and dusty up in the loft. There is some sort of insulation between the rafters, the itchy kind, but some of it is falling down. I would like to install this stuff along the rafters to save a bit of heat (and mess):

http://www.diy.com/diy/jsp/bq/nav.j...refview=search&ts=1254815759806&isSearch=true

My questioni is, should I leave the existing insulation in place? The current insulation is not very thick so should give at least a 50mm gap once the silver stuff is stapled to the rafters. I won't go completely to the eves so there will be ventilation.

Thanks for your help.

 

[mointainwalker]

You won't be losing anything by leaving the current insulation in place

Using the B+Q figs, this roll is equivalent to about 30 mm of mineral-wool so won't be a hue heat-gain.

 

[WhiteChristmas]

Thanks for your help (or should I say merci? ).

I was just a bit concerned about the current insulation pulling down the new stuff but I guess it's not that heavy.