Offers from GU - are huge price differences normal?

Don't put yourself through that, requesting half of a semi-detached house. Plan together, even if you want to use different builders, and even with different construction methods.

All offers - including the most expensive ones - can omit essential things. For laymen, there is actually only one even bigger crocodile pond than passive tendering, and you have also just hit it ("beginner's luck" off - an own goal!): namely to take on Big Names at the same time.

Is this supposed to be an Olympic triathlon?
1. half a semi-detached house; 2. without an architect; 3. Big Names

The neighbors have already finished planning, we got the plot through the follow-up process. They are building with Weberhaus and have signed their contract etc. We have their designs for orientation.

What speaks against Big Names? How would you proceed? An architect is even more expensive.. And some smaller companies have also declined us due to too many orders..

The neighbors have already finished planning, we obtained the plot through a catch-up procedure. They are building with weberhaus and have signed their contract etc. We have their designs for orientation.

Oh yes, I forgot:

Our neighbors have already planned their house completely with Weberhaus. We got the plot through a catch-up procedure from the municipality and do not want a prefabricated house.

Nice that you know their plans.

What speaks against Big Names?

Primarily the lack of equal footing. I always prefer to be a partner rather than a victim in business.

How would you proceed? An architect is even more expensive.

An architect is not more expensive. What you "save" in architect fees nominally by using a general contractor figuratively is paid for with botched work due to lack of detailed planning, most visibly in the form of pipes and cables boxed in with drywall. I would always plan with a self-paid architect, put the project out to tender, and also have them supervise construction. See "Von Bauleitern und ... Bauleitern" (I am not allowed to link it here, but you can contact me – see "Information" in my profile – if Google doesn't find it yet).

Hello dear forum members, we are currently looking for a general contractor for our construction project (semi-detached house, 2 floors + half attic). We have an offer of 340k, but have already received initial price ranges from 3 other companies between 410-450k. Is it really common for offers to differ so enormously? Is a price of 340 already considered "cheap"? Of course, we will examine the scope of work descriptions more closely, but which points could justify such enormous differences? Would you also be suspicious if someone offered the fixed price without a time limit? Best regards

Who omitted the time limit in the offer?

No, not an architect, several larger companies were asked. The cheapest was from Helma and a local general contractor, the more expensive ones were Viebrockhaus and two other local companies.. Best regards

I would be very interested in how Helma differs from Viebrockhaus, and whether they are really better? Please elaborate on this further.

Before you try to compare companies, compare the offers. How are individual versions described? What is not described? The differences probably lie in the offered version.

how Helma differs from Viebrockhaus

Simply put: Helma's style is sporty and simple, compared to the rather rustic Viebrockhaus. In the usual inquiry quality of self-planning laypeople asking for "around four hundred cubic meters house," Helma accordingly comes to a smaller nominal amount as expected.