"Rick" wrote in message
...
On Fri, 22 Jul 2005 21:09:32 +0100, John Cartmell
wrote:

I'm looking to add insulation to the cavity in a conservatory wall during
building but I'm not clear what thickness of material to use. I had
assumed
that it would be necessary/best to fill the cavity but investigations
suggest
that less than 1/3 this thickness seems to be generally used.
Is one option a false economy or the other a waste of money?

NB We are intending to use the room in all seasons.

From whant I found when I built my house, u have 2 choices

100mm full-fill cavity bats, they must be the "full fill" type.

OR

50mm kingspan, held against inner leaf.

Both have the same U value. The kangspan can not be used as "full
fill".

The floor, you can put 100mm kingspan in.

Having said this, the windows are gonna be a much bigger heat
loss/gain problem.

It all adds up. The floor is a large area and added to the dwarf walls a
reasonable percentage of the overall area, so worth insulation well. If the
conservatory is against the outside wall of the house the conservatory acts
as an extra layer of insulation on that wall. As no rain will penetrate
this section outside wall, full filling the house wall against the
conservatory is a good thing. The problem is getting inside the cavity, so
a spray in foam would need to be used.