You cannot repair a listed building the same way you repair a newer property. That mistake causes more problems than most people realise. Across Newcastle upon Tyne and Durham, many older buildings were built using lime mortar, natural stone, and breathable materials. They were never meant to be sealed with modern cement or heavy waterproof coatings. A repair may look neat at first. Then, months later, damp starts showing indoors. Mortar cracks again. Stone begins to crumble