I have a 1989 dormer bungalow. which has 2 inch aero board insulation in the cavity.The front of the house in other words the outer leaf is Leitrim ( sandstone) stone. I am looking at all possibilities for improving insulation. I had a guy have a look at option of dry lining but this would involve a lot of disturbance, removing rads, 3 handbasins as I have them in 2 bedrooms and a 3 Rd in en-suite. Large fitted wardrobe installed in the main bedroom approx 3 years ago.Removing small kitchen unit and losing bath in main bathroom and maybe shower in en-suite ioff the main bedroom.Is it impossible to consider external insulation given that I do not want to loose my sandstone frontage.Have any other householders with possibly brick frontage got around this obstacle?.I could consider pumping the walls and do selective dry lining I.e only in certain rooms.Any suggestions please.