I am trying to work out the U values of the existing external walls of my house so that I can decide on the best material and thickness for dry lining on the front elevation and EWI on the back. The house is in Brighton, Victorian and the walls are Bungaroosh. See below for an explanation of Bungaroosh!
Never heard of bungaroosh or bungarouche? It's a building material used in Brighton by Georgian and Victorian builders. A conservation expert for the local council explains:
The material is basically a freely interpreted flint rubble. A lime mortar was made up, and poured into shuttering, and anything else that came to hand was bunged in too. This could include old bricks, bits of flint, odd lumps of wood, lumps of chalk, in fact anything solid. [snip] It is not unusual to find vertical joints between the front wall and party walls. This can be a boon if the front wall falls off, since it leaves the rest of the house standing. [snip] Most of the time ... bungaroosh stays in place — probably through force of habit. All the bits of timber in the mixture tend to create a rather pleasant breeding ground for rot and exotic fungi. Since the mixture is very porous, the rot circulates quickly, and can usually find some damp somewhere to feed on. In fact bungaroosh has to be a little damp. Too dry and the now leached mortar crumbles, too wet and it becomes mobile. My predecessor considered that on this basis you could probably demolish a third of Brighton with a well-aimed hose.
Anyone come across it or can give ideas on how to model it to get a fairly representative U value? I have an NHER U value calculator as I am an NHER SAP assessor. Also my thoughts are that the insulation material I use must be breathable so that the Bungaroosh stays a little damp.
Thank you, Maria Hawton-Mead