In the 1950s, there was an agreement among the neighbors that the boundary distances only had to be 2 m; currently, this would only be possible with the neighbor's signature, which unfortunately is not feasible. As described in the opening post, after consultation with the building authority, a deviation from the building line is possible, hence the rotation for better lighting. 7.5 x 12.5 would unfortunately not fit, but only just over 6 m in length. Unfortunately, I will only have access to all the documents again in a week, but I have sketched the building envelope (see attachment). Yes, I meant that widening the building volume would be too expensive for the added value we gain. The greatest added value would of course be a larger kitchen. We had roughly planned this before, but we definitely need to go into more detail here. Thanks for the information!