There's no shortage of advice hereabouts regarding the folly of replacing lime plastered wall coatings with gypsum products, invariably with reference to the breathing of said walls. So, what's the consensus, if indeed there is one, with regard to battening and overboarding the same said walls? Obviously there will be a gap of at least the batten thickness between the board and the plaster (or bare brick/stone), but should the space be vented (internally)? And should the walls be sealed for dust controlling purposes prior to overboarding?