Tim Slaney, who worked at West Berkshire Council as planning and transport policy manager between April 2005 and April 2007, claimed he would not have needed permission had he lived in the Royal Borough of Windsor and Maidenhead, where he is currently head of planning and development for the district council.
Residents of Fairview Road, Hungerford, were stunned to see the construction take shape and demanded to know what was going on.
West Berkshire Council told the Maidenhead Advertiser that the building work was unauthorised because the necessary permission had been neither sought nor granted.
Council spokeswoman Peta Stoddart-Crompton said: “Mr Slaney is reconsidering the design of the loft extension.
“When the redesign is finalised and plans are drawn, a planning application will be made.
“In the interim Mr Slaney is undoing the unauthorised works by removing the dormer box that had been erected on the rear roof slope of the house.”
Slaney told the Advertiser: “West Berkshire Council accepts there was absolutely no deliberate attempt on our part to flout the planning regulations.
“As soon as the matter was brought to the agent’s attention we called a halt, advised our builders and the works have already been taken down.
“We will now be applying for planning permission as required. The way planning laws are applied varies from area to area and, if this had been a town in the Royal Borough the work would not have needed planning permission.”