The Insulation of the External Wall makes the wall moisture resistant. However, an insulated property requires, also a good internal ventilation as the Insulation is a double side protection.
The installation of the External wall insulation reduces the U Value.
This process will change the external appearance of the house. In most cases it may require planning consent before undertaking insulation works, so do check with your local authority from the outset. For homes in Conservation Areas and for listed buildings this is likely not to be accepted.
We would like you to pay attention that under Building Regulations, if 25 per cent or more of a wall is to be insulated externally, it is typically necessary to bring the entire wall up to current standards.