"The Natural Philosopher" wrote in message
...
Rick Dipper wrote:
I have worked out the U values of the insulation I intend to use in my
cavity walls, I have 2 solutions
1) Blocks -celotex-rockwall = 0.224 W/m2K
2) Blocks -2 * rockwall = 0.255 W/m2K
I did not take account of the external wall, plaster, mortar or wall
ties in working out these figures. The external walls are 600mm stone
walls.
Normally I would go for option 1, but its arround twice the cost of
option 2, a whole lot more difficult to install (I am building the
inner wall second) and there is not a big difference in the insulation
values.
Any ideas on how I work out if its worth it ?
Is it as simple as working out the temperature difference, the surface
area of the wall, to work out the loss via the wall, and then mutiply
by the cost of a watt of heat ?
My thoughts right now are to save the money, and use it to put extra
into the roofspace.
Thanks
Rick
I went with 2x rockwool purely on cost.
El cheapo eh.
It was good enough.
It is not!!!!
Despite IMM's blatherings, once you meet
building regs U values, you are
....insulated well below Germany, Scandinavia, north America and most of
western Europe.
Go for 0.1ish
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