Single single rear extension of victorian house built in early 1900s

Camillia123

I am trying to get mortgage of our house with 2 storey rear extension having a kitchen in the ground floor and bathroom in the first floor of the extension and to note all the properties in the area have the same floor layout and is built around 1930s. Rest of the house is a solid wall. Before applying for mortgage we knew about this problem and added an external wall insulation done by Instagroup to the single skin but that also failed in the valuators mind and said although we have external wall insulation that does not make it structurally adequate. What are your suggestions on what do we do in terms of bringing it to the current building standards. We have asked our neighbours who bought their property a year ago and sold their property recently and what documents they got to fulfill the lenders and they showed us building regs certificate for internal insulation. We are confused now that if just internal insulation would suffice the building regs why did our Valuator rejected our mortgage .