The original Victorian external lime render and internal plaster was a breathable construction but the lime has been replaced with cement externally and gypsum internally with vinyl paints applied to both sides to really make sure that water vapour can’t move through the structure! Perhaps acceptable on a modern building but risky on a solid walled Victorian property with limited/No DPCs, dodgy eave details and garden walls etc abuting. Cracked render then allows moisture in, especially driving rain, which is then trapped behind impervious layers resulting in soaked brickwork. The real issue however, is the timber joists which in my case bear into the brickwork on the rear elevation. The brickwork to the top floor bedroom was soaked due to faulty rainwater goods over 7 years ago and has never dried out. Surprisingly the joist seem to have survived considering their prolonged exposure to damp brickwork but perhaps even though the house was very poorly built, the timber may have been much better quality than used today and/or the timber was able to wick away the moisture. Not the case for the timber noggins placed in the walls for fixing the skirting, which has disintegrated. The ground floor kitchen window had timber lintels installed probably in the 80’s/90’s and these have totally rotted through where they bear onto the brickwork. It’s all about moisture and being vary careful not to trap it within the building structure. Images below show the rotten timber lintel and damp brickwork (inside face)
