Is the house purchase appraisal binding?

We are currently looking for a property and then came across the offers from prefabricated house sellers including land, etc.

You have to be very careful with that. Often these supposed plots of land do not exist, or they do not even belong to the prefabricated house sellers. In the new development area where we found our plot, several large prefabricated house companies advertised very aggressively.

Only after signing the contract were the buyers informed where the new development area is located – in this particular case, however, the seller of the plots did not want to support exactly these aggressive companies and then did not sell any plots to the contract signers. This is certainly a special case, but in general, it is important to be cautious.

Especially if it is apparent that you are buying house and land together, you have to pay real estate transfer tax on both, instead of only on the land – which can even cause considerable additional costs during customization (if the house becomes more expensive, then also the amount of real estate transfer tax).

Faster when it comes to pure placement, yes, but you wait up to a year or more until the appointment. Cheaper with the same equipment and performance almost never. It may be that you get volume discounts from suppliers, but this is eaten up by the bureaucracy and the above-average equipped legal department... Why should a supraregional general contractor be better connected in the region than a regional one? Everything from a single source in the sense that really all trades are carried out by one company will probably never exist. These are usually subcontractors for both supraregional and regional contractors. The regional one has probably been connected and intertwined in the region for years and works with good companies on a long-term basis. The supraregional one will always take the cheapest and definitely will not shy away from burning subs (which can also be good) (and the good subs then no longer work with them because they don’t need to). Always compare the specifications of the construction work (Bauleistungsbeschreibung) in addition to the price. Anything that is not listed there or that is indicated as client-supplied you have to pay/provide! Regarding finding, first of all, the internet is of course your friend. Then the classic Yellow Pages. Search for construction blogs from the region. Simply drive through new development areas or single-family house settlements and look for new houses. Sometimes there are still signs from the construction companies on the outside. Or just ring the doorbell and after a brief admiration of the house ask about experiences and the construction company. Ok, in these times the last tip should be treated with some caution, but in spring you can see some people standing in the garden again. Ask around in your circle of acquaintances.

If you are not "set," then use that, i.e. choose the house builder primarily based on where the "chemistry" fits, the building material is secondary – you can build decent houses from many things, and the philosopher's stone or the wood of fools does not exist. I would approach the plot the same way and consider both undeveloped and developed plots equally – on the other hand, you might have to be less flexible with the desired location. The "degree of turnkey completeness" does not depend on the material either – on the contrary: offers excluding the base slab are even more common with "prefabricated" builders. On the topic of "plot service," I recommend my posts on the keyword "pre-sale" (and for plot searching "11ant Barthel"). Incidentally, there are also experts with more "solid house" experience and others with more "prefab" house experience. First, find a plot – and if it is undeveloped or has a structure in need of demolition, then we will see further.

I also think the material is secondary. Here in the forum, the rule applies to use what the company knows. What it then is should not matter. I find that convincing.

The first consideration we had here was that these would have to be faster and cheaper than regional home builders. Also, there was the idea that with the prefab builders everything is handled (organized) from "one source" (sanitary, electrical, foundation, interior finishing, roof,...).

The larger prefab builders all have an elaborate sales system with model homes and representatives. That is not cheap and in the end it comes out of the budget. Of course, you can save a few euros if you only calculate the static calculations once, but generally the sales costs are higher than what you save by choosing a standard house.
And especially on the topic of "everything from one source" you have to be careful with the nationwide companies. They do everything from the foundation slab upwards, and even if you buy the foundation slab from them, usually the preparation of the property is the responsibility of the builder: earthworks, sewer work, crane site, construction power and water, etc. The coordination effort then also remains with you and if something doesn’t fit, you have the problem.
At first we were very much for large companies as well, but now we are about to sign with a regional general contractor. Besides the price (which is a bit cheaper with comparable size and features), the main thing is that he also does the things that others like to push onto the builder.

Move-in is approx. 1 year after the building permit for all providers (although Schwörerhaus did not want to make a clear statement there and rather meant something like 15 months or more...). The prefab builder delivers quickly but has many waiting times, e.g. 12 weeks from the building permit until work on the foundation slab begins, from that point another 12 weeks until the house is erected, then interior finishing.

We are currently looking for a property and came across the offers from prefabricated house sellers including land, etc. Our initial thought was that these would have to be faster and cheaper than regional house builders.

Catalog prices are 1. starting prices and 2. a large amount of money that has not yet been mentioned is missing.