Financing land and house construction

Personally, that would be too many liabilities and too little equity for me. It's definitely a bit naive.

You calculate acquisition ancillary costs at 25,000. The real estate transfer tax alone in Hamburg is 5.5 percent or 17,875 euros.
In addition, a minimum of 3.25 percent broker fee is another 10,562 euros. Notary + land register + municipal fees are nearly 7,000 euros more.

That makes total acquisition ancillary costs already 35,000 euros. The first 10,000 euros are already accounted for.

Kitchen 15,000 euros? More like 30,000 euros if you don’t want one from POCO. You won’t even get a kitchen at Obi for that.

154 sqm living space. I find that very little to not sufficient with 3 children. You need 3 kids’ rooms + bedroom + bathroom + possibly walk-in closet in the upper floor.

Everything is tight.

I consider the construction costs of just under €3000 to be somewhat underestimated. Or do you already have a concrete offer? Due to the current situation in the construction industry, I would rather set the sqm price a bit higher.

Based on an offer from Viebrockhaus. The incidental construction costs already include 15k€ for upgrading. (certainly requires some discipline)

I would worry less about the kitchen. We are currently having ours made by a carpenter and have about 4.5 sqm of quartz composite and solid wood countertops and end up under 20k including appliances at about 1000€/piece on average. There is still quite some room to go down :) 15k for sampling, on the other hand, is probably too little.

Thanks to your extremely good salary, it somehow works out (the 3000€ installment is definitely manageable with a 7700€ income), but personally, that would also be too big a commitment for me.

I would reconsider the expenses again, just the example of vacation: 200€ per month for vacation is about 1 week of vacation per year on average in Germany, with 3 kids probably even less. For example, we already need 100€ fuel costs (=one tank fill) per month just to visit friends or grandparents...

Which model exactly? Is the QNG surcharge already included? Can you read the construction service description so that you can see what is missing? 460k seems low to me for a Viebrockhaus...

How much are you calculating for earthworks/foundation slab/waterproofing? And how much for flooring/painting?

10,000 seems very tight for fencing/terrace/paths/driveway... Even for materials only.