KFW 50EE or 40EE - Is the upgrade worthwhile?

With the masonry garage, one side wall of the house is a garage wall, a prefabricated garage stands attached to the house.

You should de-naivify your ideas of construction facts and connections – for example by reading around here a bit :)

According to the general contractor, these gaps can sometimes be inhabited by wasps or allow water to pass through...

If this is supposed to be a description of your general contractor’s construction method, then you’d better choose another one.

In reality, site-built garages also have independent walls on all sides touching the house for static and thermal reasons, and are otherwise properly sealed elastically – unless the general contractor takes the position of having nothing to do with the “client-ordered” garage, and its installer sees his job as done once it is unloaded. But anyway, I recommend an architect to you, no matter who builds or supplies house and garage. I hope I can get your wife on board with this opinion as well ;-)

Besides, I’m not building a nice house to put two ugly concrete blocks next to it... Of course, that opinion doesn’t help me at home either...

Does that mean your wife is "pro" car box? – by the way, I have several ugly ones (the garages, of course), all out of sight from my home.

The prefabricated garages would also come through the general contractor... he's a construction company with 150 people...

Yes, she also finds architects nice but then the costs would go up even more, I think, right? Basically, I would have a lot of time for coordination, etc. for professional reasons...

Does that mean your wife is "pro" car box?

The car box consisting of 3 prefabricated garages (2 driveway gates) is supposed to cost 34k... If you only want one big gate about 45k... For the same in masonry about 60k is called for...
But yes, she only sees the costs here... like with the ventilation or electric blinds that are supposed to cost almost 9k...

Yes, I think architects would be nice too, but then the costs would increase even more, right?

"Or" is the correct answer :)

The car box consisting of 3 prefabricated garages (2 driveway gates)

... in my opinion would be three boxes. According to the description, they want to offer you a three-part set, that is, two single garages with cut-out side walls assembled together, and behind them a third one without a gate, used as a storage room?

Basically, for professional reasons, I would have a lot of time to deal with coordination, etc...

An architect does not only coordinate, but tell me more ...

Or" is the correct answer

So it can also be just as cheap/cheaper than a general contractor? Learned something new :)

According to the description, they want to offer you a three-part set, so two single garages with cut-out sidewalls combined, and behind that a third one without a gate, as a storage room?

Correct since we don’t have a basement.

but tell me more

I work max 1-3 days a week (not full week Mo-Fr). Therefore, I would also have the time to talk to companies and get offers. However, I do have the probably justified fear that if I put a roof truss out to tender, I will get three offers... whether the cheapest is junk and only for cheapos I simply cannot distinguish... On the other hand, I would/want to work on the construction site on my days off... colleagues could also be recruited for that. --> but only for auxiliary work: cutting stones, carrying iron, setting supports, pulling cables, milling slots, etc... That would not be possible with the general contractor either

So it can also be the same/cheaper than a general contractor? Learned something new

I would never rule out a general contractor in the tender. But their "planning" quality is completely different. What the architect "costs" extra, he compensates for with avoided fiddling around. You can get a significantly better-built house for little money that way.

However, I do have the probably justified fear that if I tender a roof structure, I’ll get three offers... whether the cheapest is rubbish and just a low-budget hack, I simply can’t distinguish...

Let a professional do it – preferably the designing and supervising architect. The naive way laymen tender regularly leads to the opposite of their expectations. I also do tenders (and coachings on how to do them), but no construction supervision.

On the other hand, I would/want to like to work on the construction site on my days off... colleagues could also be acquired for that. --> but only helper tasks: cutting stones, carrying iron, setting up supports, pulling cables, milling slots, etc… Would not be possible with the general contractor either

Office people regularly overestimate how reliably they can carry out their own work fitting into the scheduling of the tasks. Especially many of the preparatory and auxiliary tasks are time-critical.

Let a professional do it - preferably the planning and site supervising architect. The naive way laymen put things out to tender regularly leads to the opposite of their expectations. I also do tenders (and coachings on how to do them), but no site supervision.

So we should, if anything, hand over phases 1-8 to an architect. What will something like that cost? I’ve read that with some you can also agree on a flat rate?! We are planning around 150 sqm with a double garage and a utility room ~500k +-

Office people regularly overestimate how reliably they can complete their own work in line with the timing of the work schedule. Especially many of the preparatory and auxiliary tasks are time-critical.

We are not sitting in an office We always have full days off so not just an hour after work time... Still not feasible?