Repairs to listed buildings are always a hot topic in our office - clients find it scary, we just try to summarise it as "Like for Like". Listed building repairs are not subject to Consent applications so long as there are no changes - so for example, if a window rots and falls out, as long as it is replaced with an exactly similar one, preferably with the original glass taken from the old one, there is no requirement for Consent. If you replaced it with a UPVc window, world war 3 would break out. Things get a little grey when it comes to plastering and so on. If you remove cement pointing and replace with lime mortar, in theory it is a change, and requires consent. Practically, so long as it is done sympathetically, and the mortar is carefully matched to the original by someone like ourselves, with an appropriate specification for the contractor - you will have no issues with Conservation. Similarly if you replace manky gypsum plaster internally that's been installed by your local Property Care Association damp wally, and replace it with lime plaster after cleaning all the damp proofing gunk off the wall that made it wet to start with, Conservation are not going to complain. They WILL complain if you allow wally damp man to drill 10mm injection damp proofing holes in perfectly dry Georgian handmade brickwork - both you and wally damp man will be liable to criminal prosecution.
Maintaining a Historic Building is all about firstly understanding the materials that were originally used to build it. Changes to the materials are the usual cause of deterioration, once other natural causes like damaged roofing, broken drains and so on have been sorted. Maintaining your building will focus on introducing breathability - making sure that any water that is able to enter the building envelope can escape, and is not trapped.Our building maintenance plans are all about specifying materials, and reducing moisture loading on the fabric - better ventilation, better drainage, constant low temperature heating. These critical factors govern the main agents of decay for an old building, and when managed, will substantially reduce any problems with the building.