"keith_765" wrote in message
...
Cut
But how cold is it in winter. Doubt if you can have too much insulation
so
I'd do it but remember you need to leave 50mm airgap above the
insulating
blocks.

What's the point of leaving a 50mm gap between felt underlay and
insulation,
unless you introduce an air flow vent at eaves and ridge.

It's a 70s bungalow so it most probably has air flow at the eaves. You need
to either open the ridge or bridge it to allow the airflow to pass through.



8" or 200 of insulation quite adequate.

Assuming you mean fibre or Rockwool, that doesn't even meet the current
building regs, let alone actually make a real attempt to save energy. 265mm
is needed so regard 300 as a min.