On Sat, 29 Dec 2007 13:51:04 +0000, Mike Barnard
wrote:

Hi.

I need a basic chart showing the heat losses through a loft area if
there is no insulation, 50mm, 100mm up to the 265mm nominal 'perfect'
insulation. Anyone know where there is one or the facts (validated)
so I can draw one up for myself?

Along the lines of...

One sq metre of uninsulated plasterboard has a U value of... ?
Ditto with 50 mm standard rolled fibre insulation.
Ditto with 100 mm, 150 mm etc.

It's so I can show someone a comparison so she can decide just when
enough is enough compared with keeping spending more and more on more
materiels.

I am googling, and it's ongoing, but all I find so far is detailed
tech guides or company ads. I'll bet someone on here has a link
already!

Thanks.

Interesting answers, thanks. All I really need to know is whether
adding another 150mm of insulation will make a big difference to the
existing 125mm. So If I had a chart as described I'd have an idea of
a 'typical' heatloss for various depths. At what point does it become
pointless (oops, bad english) to add more? Is it worth 300mm? 500MM?
Where does one reasonably stop?