TIP 6: NEVER ASSUME YOUR 'REPAIR' DOES NOT REQUIRE LISTED BUILDING CONSENT
Works classified as 'repairs' to historic buildings should not require Listed Building Consent, but therein lies the rub as this is a notoriously grey area and will differ from one Local Authority to another.
Take re-roofing works for example. This goes well beyond a 'repair' and will always require consent as it will involve replacement of a significant element of the structure, it will typically involve a decision to use new or second hand tiles (another hot issue as these will be provenance questions over the latter), could cause potential changes to the environment and therefore unforeseen consequences caused by insulation requirements, and the need to ensure adequate ventilation.
Then there's the emotive issue of damp proof courses, the bane of every Conservation Officer's life as they rarely see an application for consent for works which cause more damage to historic fabric that anything else. Suffice to say that the best advice here is never to insert a chemical damp proof course in a traditional building and never to listen to the 'expert advice' offered by companies offering their services in this area (see Tip 2).
This will also apply to works which can be considered temporary - secondary glazing for example. Many would argue that this work does not involve alterations to the structure and is easily removable, so therefore should not need Listed Building Consent. Some Local Authorities agree with this approach, but as ever in conservation it's not that simple. Take the fixings for example, as the work will usually involve drilling into historic fabric which will cause some degree of irreversible damage.
Then there's the design to be considered, as the frames should be slender and line up with existing window glazing bars to minimise the visual external intrusion. Even so the new window will inevitably look different from the inside - and remember historic buildings are also listed internally.
This isn't all however, as secondary glazing will also create a change to the internal environment - and as many historic buildings will have modern impervious plaster here, with cement mortar pointing externally this is potentially a recipe for disaster, so discreet, sufficiently sized ventilation grills should also be incorporated.
Your Conservation Officer will understand how the building works and will be able to make a professional judgement based on what they see, so it is worth reiterating that you should not make assumptions and check with them first before undertaking any works - otherwise it could prove costly in financial terms but also for the health of the building.