In reply to Arthur Fonzareli (the Fonze):
My parents are at the end stages of renovating a crofting cottage on Arran, and decided to go down the lime route. The house is rubble stone walls built on a slate flagstone foundation.
The house was rendered (with big cracks), had lots of concrete patchwork on the outside and the inside of the walls, and the soil layer was up to 50cm above the slates at one end of the house. it had been uninhabited for years, and was very very damp.
The concrete has all be ripped out, and lime pointing reapplied to all the walls. They've decided not to render the outside. When the concrete was chipped off, the stone undrneath was saturated, not nice...
The single most important thing I think they have done is dig a a drainage ditch round the bottom of the walls, inside and out, to bring the soil level down to the slate flags. This means that damp cannot penetrate into the stones and rise from there. They've put in new joists and a suspended wooden floor, with insulation/membrane underneath. House is now dry, and looking great. You will need a dehumidifier, and it will take a lot of use...
If you look at damp companies, they will probably recommend you get a solid floor complete with DPC, and install some kind of DPC in your walls. You may need neither, especially if you have a slate layer at the bottom of your walls, as this
is a DPC, as long as the soil level doesn't breach it.