Donwill wrote:
"The Natural Philosopher" wrote in message
...
Donwill wrote:
An external wall in an extension I'm building is specified as 0.34U
value, made up as follows:-
Externally rendered 100mm dense concrete blockwork.
80mm cavity part-filled with 40mm Kingspan TW50.
Inner leaf 100mm thermalite block.
Drylined internally with 9.5mm plasterboard and skim.

As this is a kitchen / diner extension, I'm keen to tile directly on to
the thermalite and leave out the drylining in order to make it easier to
fix kitchen cabinets etc.
Almost none. The kingpsan alone is about 90% of the insulation.

What will be the thermal effect of leaving out the drylining, and by how
much will the U value be changed.Will the building inspector be
interested?
BTW the extension was started prior to April 6 2006.
Do the sums yourself.

I believe you add up the resistances as they are in series, trouble is I
dont know what value to give to the individual resistances except for the
Kingspan. I've not seen a figure given for the gap behind drylining, I
assume it varies according to the gap dimension.So maybe you're right the
magnitude of the change in U value will not exite the BI.
Cheers
Donwill


No, it won't. I have all the info and data and have dine similar calcs.
However listen to the man who advises not tiling onto block directly -
he seems to have a valid point.