At Urbane Eco, we quote for 3 different external wall insulation systems: Graphite expanded polystyrene (EPS), mineral/rock wool and wood fibre. There is quite a price difference between the systems, so we hope the following information will help you to decide on the system that’s right for you. (We will always let you know if for any reason a particular system is not suitable for your property).
Wood fibre is the most robust system: it is hygroscopic meaning that it will draw moisture out of wet substrates and allow it to evaporate from the surface. It is vapour open, meaning it will allow water vapour to pass through it. Wood fibre is also more dense and has better thermal mass, meaning it will hold heat better. Wood fibre is also the most environmentally friendly, being made from waste wood from the timber industry and using relatively low energy in its manufacture. See here for further information on wood fibre.
Mineral wool is good thermal and acoustic insulation, but is not hygroscopic like the wood fibre. It is vapour open, meaning water can pass through it, but it will do so relatively slowly and does not draw the moisture out as the wood fibre does. Still a very robust system. See here for further information on mineral wool.
EPS: Simple insulation that acts like a tea cosy over your house: it will not deal with any damp or moisture in the walls. We have installed this system on many houses: it’s good insulation, it will keep your house warmer, but is not vapour open and not hygroscopic. See here for information on EPS systems.