Lobster wrote:
The Natural Philosopher wrote in message ...


Agreed. You should try and put the celotex down the sloping bits, with
an air gap above.

Probaly means ripping out all the ceilings tho.


As my house has this same configuration, and comes with the original
vintage 1913 insulation down the slopey bits (ie none) I've been
wondering about doing this myself. However, not sure I have the
stomach to pull down all that lath and plaster etc.

If I was to stuff Celotex slabs down the sloping 'slots' from above,
how worthwhile would that be, given that the slabs would certainly not
be a perfect fit between the rafters? Would the small airgaps I'd
inevitably leave cause so much heat loss as to render the Celotex not
cost effective?


Probably. To be honest.

In comparison, how effective would it be to attach that thermal-lined
plasterboard(?) over the top of my existing ceilings?

If you have the room, FAR more effective IMHO.


Thanks
David