Hi,

I want to improve my loft insulation. I already have approx 100mm
rockwool between the joists and want to either add another 150mm
rockwool or fibreglass insulation over that OR staple Airtec type
insulation to the underside of the rafters. I'm considering the stuff
sold by Screwfix

http://www.screwfix.com/app/sfd/cat/...50913&ts=45531


How do these two forms of insulation compare for actual insulation
efficiency?

Two other considerations.

If I go for the 'traditional' fibre roll I really hate fibreglass but
I've read that thickness for thickness rockwool is not as good an
insulator as fibreglass - is this correct? Do the rolls with a
polythene cover really make a difference to the amount of fibres
released into the air? I use the centre of my loft for general
storage.

If I go for the Airtec type insulation will the extra heat reflected
back towards the roof damage the roof felt? I gets quite warm on a
summer day as it is.

I would really appreciate some advice on this as I want to get it
sorted in the next month or so.

Regards,

John Smith.