Cavity wall insulation (probably thick) questions!

[Cornish Maid]

We live in a 200 year old farmhouse with the majority of main walls being solid stone or cob and 18" thick. At the rear we have a single storey extension which was originally added in the '70's, containing our utility and bathroom. This was originally built as single skin, but we upgraded to cavity wall (adding a 2nd skin of blockwork) in 1997. We have just upgraded the loft insulation in this area, and are considering cavity insulation. However, the external wall in one area is literally built into the bank at the rear of the house. This means that there is no external access to the outer skin, so the insulation material will have to be installed through the inside. Our only experience of post-build cavity insulation is via the outside wall - can it be done from the inside?

Also, as the outside wall is against the bank, would filling the cavity create more problems than it solves, ie ingress of damp from the surrounding ground etc.

Any advice much appreciated.
Thanks

 

[gasmick2]

if its that close to the bank i would have thought it should have been tanked anyway on the outside brickwork , just as cellars are done , if its been done then i do not see a problem as most fillings are now fibre not solid foam like they used to be.
Mind you you could allways batten the wall out and fix insulation sheets
and plasterboard over it that would give above the regulation req wall insulation there is also a very thin sheet that looks quilited thats well over the req its only 1./4 " thick and is used in roof insulation but its £200 a roll of about 20mters
but you pay you money and make the choice whatever suits you best

best of luck mick