How to build a prefabricated house? What to pay attention to during construction and financing?

I am a complete beginner in the field of new construction or real estate in general.

That is no shame. Everyone starts with something at some point. However, you will not be successful if you do not read up on or acquire knowledge yourself. There are things that no one can take care of for you. A forum can support you though.

What can you recommend to us?

First of all, check your own finances. Money is not just equity; what comes in monthly and what goes out is also important. Here you can enter your data. While you do that or gather the data, you will probably already realize whether it looks thin or rosy. A household budget book is helpful if you don’t happen to receive €8,000 every month in your account. Classifieds, without eBay, are linked with mobile and house portals, but by the time the data is transmitted, the real bargains are sold. Therefore, subscribe directly to the search engines. And don’t just look for “house” but also for “land” or vice versa and/or condominium. Don’t narrow down the surrounding area too much. Often you can get to work faster by bus and train from a further distance than closer in a straight line.

How does the search for a property work?

You should prepare yourselves for the fact that you will probably be searching for several years in Hamburg and the surrounding area. Of course, something might coincidentally come up for you right now, but the likelihood is rather low. The search itself is difficult, time-consuming, and also filled with plenty of competition. During this time, you should specifically increase your equity and regularly scour all available sources.

I am a complete beginner in the field of new construction or real estate in general. My wife and I would like to have a prefabricated house built because it is probably one of the cheapest options.

Nothing could prove the first sentence better than the second.

I’d be happy if someone could give me some tips on how to proceed and what I need to consider? We are in our early 30s and currently have limited equity of €40,000. What can you recommend to us?

Early 30s, very modest equity, you don’t mention children. I recommend starting at the very bottom of the property ladder. So definitely not aiming for the dream house in just one step. Perhaps a young used house (not significantly older than built in 2010), either small or with a granny flat (and move into that yourself). It should be big enough for the first child until school age, no more, bigger things come later. So build only later, beginner's luck is often cured already now. Externally (therefore including the quotation marks to google) you can find my "Ein Hausbau-Fahrplan, auch für Sie: das Phasenmodell der HOAI!" (and at the same place also "Das Zwischenhaus: ein Sprungbrett", which I see for you rather in the next stage). Here to warm up the forum search with the keywords "Grundstücksservice" / "11ant Leerverkauf" and the 11ant Barthel tips. It’s better to enter the local financing section only with the usual hockey protective gear.

Do not narrow down the surrounding area too tightly. Often you can get to work faster by bus and train from a more distant location than from somewhere closer as the crow flies.

To discover suitable places, I find the tool "travel time map drive time radius" (top search engine result) practical: for example, enter Hamburg Central Station in your case and be pleasantly surprised by the places within a 30, 40, or even 50-minute public transport radius.
You can then check these places against your other criteria, most likely the price level.

My wife and I would like to have a prefabricated house built because it is probably one of the cheapest options.

And what exactly leads you to think that?

We live in Hamburg and would also like to build nearby, preferably in the surrounding area. (...)

Therefore probably also the low equity,

But that also means, if

We live in Hamburg (...)

remains as it is and also

(...)would also like to build nearby, preferably in the surrounding area. (...)

remains as it is, then even with 20 years of "biting the bullet" it won't work.

It is anyway the case that it is hardly possible to save meaningfully against inflation. If the land price alone of 500,000 EUR increases by 5% annually, 25,000 EUR evaporate into thin air without gaining any added value.

For Hamburg and the surrounding area, you simply lack the means in your early 30s.