It is a good idea to speak with the neighbours and learn their intentions. It will serve you much better if both of you extend in a similar way and similar location (both extend on the party wall, or both extend on the other side) so you don't end up with an unpleasant outside patio. Permitted development usually allows you to extend to the rear up to 6m without permission. the shape is not the issue. You can easily get detailed information from your local planning officer. As for the extension, I will defiantly look into making the front sitting room bigger as it is not very big, or create a second lounge/TV area in the extended part. We can help you explore your options. Check out what we do, we have a unique service focusing on redesigning layouts. visit our website: www.betterspace.co We offer a low, a fixed-price package that include tailored design, furniture layout recommendations and a professional floor-plan drawing as well as a 3D package which includes a 3D floor-plan and photo-realistic images that will help you visualise your new design. You can use promo code ‘houzz’ for a further 15% discount!

I also think it looks fab but you should consider if the doors are in the best place. The door to the kitchen is in the corner of the kitchen which could limit furniture placement in there. The back door opposite the kitchen door has possible privacy and draft issues to consider. The pantry door again limits furniture placement in the kitchen. You have also a white square in your plan which I assume is an outside store- you may decide the space is better used inside. If it were mine I would perhaps have a dedicated boot area and separate laundry area so that dirty boots don’t cross where the clothes cleaning happens. My alternative layout also makes thinks easier if you hang sheets from a ceiling mounted clothes airer. You might also consider if the sink will ever get used, if you need a window (a roof light might be better depending on what you look out on). I would also be considering if you need an additional Dishwasher in there. I would also move the tumble dryer to the outside wall- some need venting but also they vibrate so quieter away from the kitchen wall. I personally think more shoe storage is invaluable so perhaps you could have additional shelving for this purpose.

thank you for all the input! The house is built in a slope so the ground floor has no exit in the back and no windows. The 1st floor has two 5mx4m rooms. One of them was used as a living room/TV room and the other as a bedroom by the previous owners. On the 2nd floor, there are two more rooms with partially sloping ceilings, but vertical windows and quite usable. We would like to use these two 2nd level rooms as a bedroom and office. Our current thinking is that one of the rooms on the 1st floor would stay as a smallish living room, and the other one as a guest room, even though has a lot of light and is as big as the living room (4mx5m). My wife does not like the idea of having our bedroom next to the living room. She prefers the 2nd floor for our bedroom, even though we have no bathroom on this floor. We only have a bathroom on the first floor and a small visitor toilet on the ground/kitchen floor. We are thinking that eventually, we might add a small bathroom (toilet/shower) into the office or the bedroom from the 2nd floor. Essentially, the house is on 3 levels with a very similar size room footprint on all levels. We are not after a "formal" dining room. But we like to have friends over for apéro and dinner. Making the dining room comfortable would definitely make sense since we would like to use this floor efficiently and get the most out of it. Since the living room/salon is on the 1st floor, and is smallish, and far from the kitchen, I imagine this room more of an after dinner place to relax, and when having guests to continue here after dinner and perhaps enjoy a digestive and a good chat. We have no kids, yet. @Christine Harrison - so this is a less deep base cabinet with full width worktop? interesting... can you please find a photo of a similar arrangement?

@Billy, it may just be a trick of perspective, but it looks as though the pantry is 100cm wide whereas the 2 appliances are 60cm each, so total width of 100cm against 120cm. BUT it looks as though there is a reasonably sizeable filler, so by the time the width of that is added to the 100cm instead of the 120cm, it will even out somewhat. Now that I can see the broader room plan, I might rethink the island to lengthen it, but slim it down, depending on how you plan to use the space nearer the patio doors. I had assumed that was a dining area, but if that is tucked round the corner, then you might want to reconfigure the island to bring it all closer and give more width around the island. 90cm is at the lower end of what is comfortable.