Catalog house or free planning with architects

We are planning a fairly normal, eligible single-family house.

What you want is a larger house than average.
Larger office on the ground floor, three equivalent children's rooms upstairs.

None of the previous catalog houses appealed to us so far, since there are actually never 3 children's rooms on the upper floor.

Well!
Catalog floor plans can usually be adapted at no cost.
This forum is full of floor plan discussions where the OP wanted to change something in a standard house.

It shouldn't be a problem to deal with the general contractors (GCs) in the region or those who build in your area and look at their offers.
Because the houses offered are those that the majority can afford and pay for. You want something more, which is already ambitious for most.
Personally, I always advise, when there is a high number of rooms, to include the attic, i.e. the roof space—either as a reserve or already in the planning itself.

You can check out model houses or construction sites online or on weekends.
If someone seems likable there, you should have a conversation and ask for a house design that can be modified accordingly. Then you will already have an option in mind.
Of course, you do not have to sign anything there.

Your wish implies about 20 sqm more than an average shack and will cost accordingly more.
Funny enough, recently many houses with three children's rooms have actually been discussed here in floor plan discussions—none of them architect-designed houses.

However, there are forum opinions here: some people are here to make catalog floor plans or designs from GCs more functional and personal, others recommend getting an architect for every house.

So you should take some time for the forum and look for these houses in the floor plan discussions. Maybe you will find out who the GC is.

I would also accelerate a bit more to answer this question because first you need to choose the right direction in order to make progress.
For example, we built with a GC who is led by two architects. But they also have employed architects as well as architectural offices consisting of several architects who are not necessarily all self-employed.

Oops. And what about the higher costs incurred by the catalog house providers? Don’t they deter you?
- Marketing
- Sales staff
- Administrative overhead
- Vehicle fleet
- Catalog creation
- Show home park
- Administrative rental costs etc.
- Effort for sample selection
- Architects/structural engineers due to redesign requests
etc.
What do you think, who has to pay for all that?
(...)

That is actually quite nonsense. The show homes usually also serve as the office, and the architect also has office costs. For marketing reasons alone, they don’t sit in an overseas container on an Aldi parking lot.
All the costs you list are more or less also incurred by the architect. What the architect does not have:

He doesn’t order 2,000 heat pumps per year from Vaillant, but only about 20. That means he gets totally different prices than the large catalog house providers, and this applies across all trades.
If you go to the hardware store and buy a wheel bolt, it costs around 2.50 EUR. If VW buys those things, we might be talking about 10 cents per bolt.

All the costs you list are more or less the same for the architect. What the architect doesn’t have:

He doesn’t order 2,000 heat pumps per year from Vaillant, but only about 20. That means he gets completely different prices than the large catalog house providers, and this applies to all trades.
If you go to the hardware store and buy a wheel bolt, it costs around 2.50 EUR. If VW buys those parts, we’re maybe talking about 10 cents per bolt.

To come back to the point. We definitely want to build with a general contractor. The only question is whether we should outsource the planning phase to an architect.

Otherwise, we would be very interested in experience-based values regarding additional costs. For a brick house, there is no real prefabrication, so external planning should actually fall within the same cost range. The price advantage should actually only arise if the GC has a corresponding degree of prefabrication. So a prefab house. Does anyone have reliable figures on that?

All the costs you list are more or less also borne by the architect.

With a very strong emphasis on "less". I don’t know which architects carry around a large staff, have show houses standing around, maintain a fleet with sales employees, distribute glossy brochures along with a professional internet presence, and so on.

He doesn’t order 2,000 heat pumps per year from Vaillant,

Nope. But then again, no standard home builder does.

If you go to the hardware store and buy a wheel bolt, it costs around 2.50 EUR. If VW buys those things, we’re maybe talking about 10 cents per bolt.

It’s good that you don’t go to the hardware store yourself when buying an architect’s house but work together with tradespeople who buy from wholesalers and can enjoy the cost advantages there. Who in case of doubt then install the cheaper heat pump from Viessmann instead of one of the 2,000 expensive Vaillant units rotting in the warehouse.

By the way, a very important cost item for the really large national GUs: legal department. They have a good budget for defending against your claims.

To circle back once more. We definitely want to build with a general contractor. The only question is whether we should outsource the planning phase to an architect.

Otherwise, we would be very interested in experienced insights regarding additional costs. When it comes to a stone house, there is no prefabrication as such, so external planning should actually fall within the same cost framework. The price advantage should actually only arise if the GC has a corresponding degree of prefabrication. So a prefab house. Does anyone have reliable figures?

That is the wrong question. Building a house is as individual as nothing else. Even an absolutely identical house is priced differently in MV than in BY or Berlin. Additional costs can arise, or it might turn out cheaper. Location, the economic situation of the region, wage structures, and even material availability are different everywhere. THE price advantage you see does not exist. Not even between GC/architect + individual trades/prefab house provider.

Above all, you cannot compare. That only works if you work with an architect up to phase 6. Then you have a complete tender for all trades and receive comparative prices for identical houses from all providers (or craftsmen). And even then, providers will still offer you different proposals because, for example, they use different materials.

Oh yes. By the way, a prefab house can also be made of stone and prefabricated in a factory. For example, mass-produced by Deutsche Reihenhaus. There, concrete plants build 50-100 houses at once and store them on the yard (including windows and prepared piping for electricity, etc.).