On Mon, 21 Feb 2005 23:39:55 -0000, "Aldrich"
wrote:

Thanks very much to all who replied to my question.


The sloping bits are only about 300mm long. I really don't want to replace
the plasterboard - I have limited diy skills! So if I leave the existing
plasterboard / lathe and plaster there, are you suggesting that I add extra
plasterboard to the cold (loft) side?

No, only if you wanted to insulate from the inside, but that would
mess up your decorations or need plastering etc

I had wondered about putting polystyrene on the cold side, but still leave
some gap to the eaves. Any thoughts?

That is your best bet! Try to leave 50 mm gap on the cold side of the
insulation. There should be no gap atall on the warm side ie it should
be pushed firmly against the plasterboard otherwise its a waste of
time. You could try pushing the insulation in place then pushing in
lengths of timber along the sides of the rafters (say 2 x1's) and then
screw/nail them to the rafters so assuring the gap above the
insulation and holding the isulation onto the plasterboard below it.

Do you have foil on the back of the ceilings plasterboard? If not you
could paint a few coats of oil based paint on the ceiling from inside
the room for a vapour seal. And if you want to increase the
ventalation in the eaves some time in the future that would be a good
thing.

Celotex/kingspan gives beter insulation than polystyrene for any given
thickness plus its easier to squeeze into betwwen rafters without
snapping. Its a bit more expensive though. You get if from an Encon if
theres one near you or a buliders merchant will order it for you.

cheers
Basil