Summary of the latest Permitted Development changes - May 30th 2013. 

Extensions to Office Buildings [Part 32, Class A]

There is a similar amendment to the current PD extension rights for Class B1(a) office buildings, The maximum floorspace for additions to the original building is increased to 100m² or 50%, whichever is the lesser [previously it was 50m² or 25%].

As with Part 8, the developer must give the LPA notice of the completion of the extension works, providing details of the date of completion, and a description of the building works, including its location and dimensions.