External insulation system

We recently inspected a property in London, W1. The building was refurbished about 9 years ago and has recently shown signs of deterioration. To improve thermal efficiency the contractor had implemented an external  insulation system which involved fixing polystyrene boards on to the outside of the building before covering with a mesh and then rendering over the top. This system is good in terms of improving the thermal efficiency of the building, however this system was only implemented around 9 years ago and so the durability of this method is questionable. We have not come across this method of insulation much, especially on blocks in London.