2.5 years ago we built a garden room and new patio in the garden to our maisonette. The old garden was awful and quite a hazard.
The room is well built of mostly non combustible materials e.g. concrete blocks, weatherproof plywood, solid wood beams, shingle roof, patio doors. It is mostly insulated and has an electrical supply but not water. It is built up to the boundaries on 3 sides. It is not designed for use as a dwelling as it’s not heated. It is 4.8m wide x 3.4m deep. It has a predominantly flat roof which is 2.65m but has a sloping roof at the front to create the illusion of a pitched roof, this makes it 3.27m high.
We believed it fell within permitted development rules but now understand that these rules do not apply to maisonettes or flats. Our freeholder has said he is happy with the development and is going to change this in the lease.
I stupidly contacted the council to ask what we needed to do and they basically didnt know as people “don’t normally improve their flats”. What course of action should I take please?