I have now taken a closer look: The house could rather use about a meter more in width and then one meter less in length. That way, you don't have the disproportionately deep living area nor the missing meter to have living and dining side by side. Unfortunately, the planning constantly used 10.50 and did not consider this possibility. Then I would also, because the regular stair users are halved here, set the walking width to 90 cm (not 100) and, as already mentioned, have a spiral at the bottom. And then: has anyone noticed that 3 toilets for 4 people is absolutely excessive? Guests can, if necessary, also climb a staircase (party room builders plan that way too), but I would simply plan the ground floor bathroom without a toilet, instead with a frosted glass sliding door to the guest WC. Such a thing can be elegantly solved and saves a few square meters. And since you don't have many guests every day, you can then close the connecting door on the few days when you do.