EH 790K€, financing 480K€ - feasible with our monthly budget?

I also consider that appropriate in terms of income. But keep in mind that a sale with the incidental costs and the high interest rates, assuming the market situation remains the same, can be associated with losses of 50,000-100,000. Because only a few can afford a house at that price now, and even if you sell in a few years, it may be that the target group is so small that you don’t break even but could incur a loss. Because now is the most expensive time to build a house (land/house prices still at 1% interest rates and on top of that the high material costs make building a luxury item now)

Maybe in Buxtehude, but definitely not in metropolitan areas. Where do you want to build?

Ok, yeah, it's easy.
We have a similar net income and that works.

Btw: You don't have a property developer, but a GU or GÜ.

Thanks for the hint. I didn't know that yet.

GU = General contractor: Company that carries out a construction project with its own employees as well as subcontractors
GÜ = General principal contractor: Company or person who implements a construction project but does not run their own construction operation. The GÜ can commission both subcontractors and a GU with the construction work
Property developer: GU or GÜ who sells you a house or an apartment including the land, which is newly built

Ok, yeah, it's easy.
We have a similar net income and that works.

Btw: You don't have a property developer, but a GU or GÜ.

I assume the gap between financing and purchase price is equity? I also think, based on the pure numbers, that it looks quite healthy and feasible. With 2 children, I assume the parental leave with possible salary reductions is already over? Take another look at the cost side. Ancillary construction costs 30k and outdoor facilities 15k might be tight. What about the additional purchase costs for the land (notary, property transfer tax)? The house price quoted by the general contractor is also rarely maintained (upgrades, fittings, etc.).

Yes exactly, up to 310k EUR of equity we can gather by searching extensively and liquidating reserves. Parental leave is over for now; if we build, we need the stable income anyway. What worries me more is that we might eventually have a job change to a less well-paying employer—therefore, we don’t want to be too tight with the monthly installment. The plot is quite flat but might need to be raised by about half a meter. Should we rather plan with 40k EUR or even more? Outdoor facilities—what would be a reasonable amount? For extras, we still have a buffer of 10k EUR; kitchen plus furniture 25k EUR have already been deducted from the equity. Would you suggest a buffer for possible cost increases during construction? How much would be advisable?

When will the construction be finished? And how much rent are you currently paying? You are still building up additional capital, which can then be used for the outdoor facilities after the house is completed. Provided that endless special requests do not arise during the construction phase ;-)

Yes exactly, with a lot of searching and liquidating reserves, we can manage up to 310k EUR in equity together.

Parental leaves are over for now; if we build, we need the stable income anyway. I'm more worried that there might be a job change to a less well-paying employer at some point – that's why we don't want to push the monthly rate too tightly.

That is basically sensible as well. We do it so that we put aside a moderate amount monthly in ETFs for the remaining debt. Alternatively, if you are more risk-averse (although we’re not really big risk-takers either; we only do global ETFs), you can just put it in a daily money account and make a special repayment once a year. We have an interest rate slightly below the current ones, so we hope to get somewhat more return from the market in the long run to then repay a larger sum when the fixed interest period ends.

In general, whether you do it via stocks or other forms of investment, I am a big fan of supplementing a fixed monthly rate with a second monthly amount that you save privately and separately for this purpose. That also gives you the flexibility to access it if something unusual happens. However, you just have to have the discipline not to blow it on a Caribbean vacation. :)

The plot is fairly flat; it might need to be raised by about half a meter. Should we plan more around 40k EUR or even more?

I can’t really judge that from a distance without pictures. When I thought about ancillary construction costs, I was also thinking of things other than just earthworks. Keywords: construction power, construction water, insurance, house connections (electricity, water, gas?, telecommunications, multi-service house entry), possibly construction supervision, possibly energy consultant, surveying costs, site plans, official fees/applications, possibly architect (depending on whether you build with a general contractor or assign separately), etc.

Outdoor facilities – what would be a reasonable amount?

Also hard to estimate flat-rate. We built in Lower Saxony on a flat plot – we spent about 15k EUR on paving work – driveway, carport, access path, house perimeter, and a terrace. We were able to initially do the rest provisionally ourselves, lawn and some flowerbeds. But depending on the plot requirements, that can also get more expensive; it also depends on what you want to have.

For extra wishes, we still have a buffer of 10k EUR, kitchen + furniture 25k EUR, which have already been deducted from equity.
Would you recommend a buffer for possible construction cost increases? How much would be sensible?

The kitchen alone quickly ends up at 20k EUR, depending on how large it will be. Prices have increased as well. What people often forget are washbasins and accessories; that also depends on what is included in the contract and what is not. With some construction companies, you basically get a fully equipped bathroom, with others you have to provide many things yourself. Furniture (i.e., washbasins) are rarely included.

Regarding the buffer – we had an overall buffer of about 50k EUR in the budget, which we will use flexibly according to priority. Our outdoor facilities are also included in that. If something unexpectedly becomes more expensive during construction, our outdoor facilities will be scaled down or done step by step – many neighbors do the same; we’re all young people and not wealthy. ;)
In 2023, there will still be a local contribution for road development, the amount of which we do not yet know. The money is initially blocked in my budget (the worst-case assumption); if it doesn't turn out that way, we'll use it for photovoltaic on the roof or a nice garage door or something.
So far, this plan is working well for us. The outdoor facilities that were originally planned to be “luxurious” have already shrunk a bit due to some unforeseen more expensive items. All in all, we are doing well so far. And this is more or less how you have to present the buffer, because the bank expects proof of everything during financing, including your own equity expenses. That means, if there is money left over, we basically have to put it into photovoltaics, because the bank wants us to spend the agreed amount X. :)

Kitchen and furniture for 25k I find too tight. Maybe it's us, but our kitchen alone was beyond 20k (Nolte, simple countertop, Bora, otherwise Siemens mid-range). With the things that come up during the construction phase, we are now also beyond 20k (doorbell system, additional cost tiles/parquet, additional cost sockets/switches, special foundation, etc.). We were aware of this and therefore budgeted with an appropriate buffer.