Insulating loft

[StuPick]

Hi,

Am looking to remove all the old dirty insulation out of my loft (cold loft) and relay the lot. I live in a victorian built house which has really tall ceilings and is hard to heat, so I want to insulate it as best as possible. Am looking for conformation on whether or not it's OK to lay airtech foil insulation at ceiling level in the loft (without any vapour issues for the joists), stapled in to follow the contours of the joists, 100mm jablite slab in between the joists on top of the airtech, then another 200mm of insulation running perpendicular to the slab. My only main concern is ........ can vapour accumulate between ceiling, which is lathe and plaster and airtech foil that could effect the joists?

Hopefully someone well versed can answer that for me.

Cheers

Stu

 

[oldbutnotdead]

What are you hoping to gain with all the expensive stuff (airtech, jablite) that you won't get with a very standard 100mm rockwool between the joists and 200mm over the top?

 

[StuPick]

The airtech and jablite aren't particularly that expensive ............ but what I was trying to find out was do I need to worry about vapour settling between the lathe and plaster and airtech which could affect my joists ?

Do you know ?

 

[oldbutnotdead]

Not sure about wrapping the joists in the stuff. It'll act as a vcl, if the bottom face stays warm enough you won't get any condensation. Still don't know what you'll gain unless your loft is suffering condensation issues

 

[StuPick]

I just wanted to lay it out like a carpet in the loft then jablite in between the joists that way I could lay boards over it in certain areas fir good storage. On the outer edges is where I just would have added the extra layers of insulation roll, but it sounds as if its gonna act as a vcl then chances are it'll create condensation between the ceiling an foil keeping the joists damp which is no good