Thank you again for the answers! Ok, then maybe the idea with the architect is not the best. It doesn’t help me if I can’t compare directly. We are comparing our offer from the current developer (a large green one from the Hannover area) with that of a smaller one from Cologne, which we’ve liked even better so far. But from the smaller one, we haven’t yet received figures for our house. Of course, it’s clear that you can’t estimate whether the €265,000 will be enough; I haven’t written a construction and service description for it. It was more about whether I, as the builder, will need money “on the side.” I’m thinking, for example, about the double burden of rent/financing, where quite a bit will already go away. At the moment, we have quite a bit left over each month, but probably saving more during the construction phase is not feasible. From the €15,000, we also have to pay for a move, one or two lamps, a few pieces of furniture, maybe already something for the outdoor facilities and such. And those are just the things I’m thinking of. I’m just afraid of forgetting really essential cost points. If we choose higher-quality fittings in the sampling (sanitary or so), we can include those in the financing, right? Our developer will or already has planned a financial buffer to some extent for, for example, earthworks, construction electricity, and such. But of course, it is very difficult to estimate in advance whether this buffer is realistic. We have the soil survey on the radar. Building expert, thank you also for the detailed answers. So far, the rough planning is the draft we are continuing to work on. We know that we will have about 150–160 sqm of living space, but we are still moving windows, making things wider, relocating doors and such. Therefore, the purchase price is certainly not final yet, and so far we only have this one offer...