On 16 Nov 2020 at 21:54:35 GMT, "Theo"
wrote:

Dave Liquorice wrote:
On Sun, 15 Nov 2020 23:03:41 +0000, alan_m wrote:

You can also get real wool insulation but more expensive ...

But very nice to handle and no irritating fibres or dust. It does
shed fibres though.

It seems prices are pretty constant across suppliers. According to my
calculations:

Mineral wool: £3/sqm (200mm thick)
Encapsulated mineral wool: £10/sqm (200mm thick)
Polyester: £14/sqm (200mm thick = 100mm@£7x2)
Sheep's wool: £13-18/sqm (150mm thick)

I probably have 50sqm to do plus some walls, so that's quite a price jump.

ICBA to do the research/maths but above 8 to 10 inches of these forms
of insulation you get into the releams of diminishing returns. We've
got 4" of real wool but under 22 mm chipboard which also has some
insulation value. An IR thermometer tells me the ceiling is the same
temp as the external internally insulated with 50mm celotex walls and
an IR camera showed the the same. Internal plasterboard walls are at
most 0.5C warmer...

It's currently 4 inches, dropping to zero in some places. Thermal camera
photos aren't terrible, but interested in blocking solar gain as well as
heat loss.


Reading this, I'm not sure why you don't just celotex the ceiling (and
verticals) with, say, 75mm. You could loose board over too, without the need
for stilts over wool etc. If I had my time again it's what I would have done.

--
Cheers, Rob