House external & internal wall insulation advice by the experts at Energy Saving Grants to help you save more on monthly energy bills. Do I need Planning Permission? Planning Permission is not normally required for External Wall Insulation. However, if you live in a Conservation Area, a National Park, an Area of Outstanding Natural Beauty, or in a listed building, then Planning consent will be required. Is External Wall Insulation suitable for any property? External Wall Insulation suits a wide range of properties, both existing and new-build. How long has External Wall Insulation been used for? 1Although EWI has only really become popular in the UK within the last deacde (since the building regs were amended in 2010), it has been installed on properties in this country since the 1970s. However, in large parts of continental Europe, EWI has been used extensively since the 1950s. Therefore EWI is a tried and tested energy saving measure.