On 05/10/2010 12:36, The Natural Philosopher wrote:
Bite the bullet Richard, and lift the floor.

Then wedge 60-100mm celotex between the joists, tape over with the
approved tape. seal any edges with expanding foam till its completely
airtight, and re-lay the floor.

One of the issues I have procrastinating about doing a DIY job is
overestimating the effort and potential problems I may encounter.
Sometimes it turns out easier than I first thought, but getting started
is hard.

The OP has the training run-up available to do the undecorated room
first. Press on!!

Now, reading these posts is making me wish that we'd done the same for
the floors as well as the external walls (which we did Celotex) prior to
our recent whole house replastering. But that would be messy now, take
effort, I'd have to clean up, price of fish could rise...

See ;-)

--
Adrian C