How can we reduce the impact of our already-built extension?

We have built a single storey extension at the rear of our detached house, abutting the boundary line. The new section is 7m deep, and around 2.9m high.

The local planning authority (LPA) has told us the structure should not extend beyond 4m, saying that the additional 3m depth is adversely impacting the outlook for our neighbour, who also has a detached house.

There is a passageway in between the two properties, belonging to our neighbour, which creates a 1m gap between our buildings. How can we prevent our build from causing an adverse impact on the outlook for next-door?

I am afraid I don’t think you can. Did you secure planning consent for your extension in the first place? If not, I assume that you were working on the basis that the new strucure could be carried out under permitted development (PD).

However, if you have pushed out to the side and up along the boundary line, then I don’t think PD guidelines would be applicable – which is presumably why your local planning authority have now gotten involved. If I’m right then I think in truth you will need to engage a planning consultant who can visit your site, assess the situation and advise you on your options.