Property development - basement yes or no?

He must have been sick during the lectures about the tendering. An offer from the roofer, whose validity would have already expired before the excavation of the foundation pit, would turn the tender into a joke. The offers are not supposed to reflect daily prices at the moment of the tender, but to make the execution calculable.

I will address the topic again specifically. Maybe there was a misunderstanding. But to understand it clearly for myself in advance: From your point of view, a tender should be conducted in such a way that at the time "X" all trades are tendered per individual lot. (Where do these tenders take place? Are companies targeted directly or is there a portal where the tenders can be found by all companies? How should I imagine this?). Within the individual lots, it is defined when the work is roughly to be carried out and up to this specified execution time the offers are binding? If the construction or a trade is delayed by one month, is the offer no longer binding for the craftsman and he then submits a new one? The winner of the respective lots is selected by the client (together with the architect) shortly after the tender and then signs the contracts with the individual trades directly?

Maybe someone else can report from experience how it went for her/him :)

Maybe better not with this one after all. By the way (see also: "A House Construction Roadmap, also for you: the phase model of HOAI!") I do recommend commissioning the same architect for "the whole program," but not for all phases "in one go" (but as modules A, B, and C - found in the same place on the web - with a break after A).

He also recommended this to us and always handles it this way. The phases are commissioned step by step with him and we can opt out at any time. But we keep in mind that we want to commission all phases (just step by step).

Yes - to have the questionnaire in the initial post there. But also cross-references from here to there.

Alright - thank you! I will do it that way then.

From your perspective, a tender should proceed so that at time "X" all trades are tendered individually per lot. [...] Within the individual lots, it is defined approximately when the work should be carried out, and until the specified completion time, the offers are binding? [...] The winner of the respective lots is selected by the client (together with the architect) shortly after the tender and then directly signs the contracts with the individual trades?

"Exactly," to quote "Jan Arnaud" ;-)

( Where do these tenders take place? Are companies specifically contacted or is there a portal where the tenders can be found by all companies? How should I imagine this? ).

The architect – whom I recommend choosing locally on site – knows his regulars who recommend themselves for an invitation to participate. It is not uncommon for a client to want to include a club comrade in this circle. Public tenders for single-family houses are – even for a building volume like with or – extremely unusual.

If construction or a trade is delayed by a month, the offer is no longer binding for the craftsman and he then submits a new one?

Usually, one only tenders once nothing is delayed anymore (approvals including any road closures are fully in place, utilities have coordinated, suspicion of archaeological monuments has been cleared with a negative result). By then, a construction schedule has already been created. The content of the tender may already be known or anticipated beforehand, but the starting signal for submitting bids comes not earlier. If, for example, the basement is built incorrectly and must be redone, delay-related price increases are borne by the party causing the delay. But that also belongs to "knowing the regulars": that you know with whom you can find smooth solutions so that target and actual are only fully congruent in the lab. When it’s a home game for the regional craftsmen, reserves are planned for this; not so with the big names: they appear nominally cheaper because of this, and in case of a problem, their legal department fights it on the client’s back.

The phases are commissioned gradually with him, and we can exit at any time. But we keep in mind that we want to commission all phases (just gradually).

That’s nonsense. Take the "trouble" to google my reading tip (as a phrase in quotation marks, external links are prohibited here), it is explained there. Neither a cut after phase 1 nor after phase 4 would make sense, and the break between modules A and B is a significant "almost a phase on its own." Also, one should not give the architect a back door to eventually losing interest or "time" during the process. Pay particular attention to two points in references (is actually on vacation this week?), namely what his clients say about the accuracy of his price estimates and his construction supervision.

The architect – whom I recommend choosing locally – knows his usual suspects who recommend themselves for an invitation to participate. It is not uncommon for a client to also want to include a club comrade in this circle. Public tenders for single-family houses are – even for a construction volume like that of or – extremely unusual.

Okay, understood :).

Usually, one only issues invitations to tender when there are no more delays (approvals including possibly road closures are completely in place, utilities have coordinated, suspicion of archaeological monuments has been ruled out with a negative finding). By then, a construction schedule has already been created. The content of the tender may already be known or announced beforehand, but the starting signal for submitting bids does not come earlier. If, for example, the basement is built incorrectly and must be started over, delay-related price increases are the responsibility of the party causing the delay. But that also belongs to “knowing the usual suspects”: knowing with whom you can find smooth solutions so that target and actual conditions are only fully congruent in the lab. When it's a home game for local craftsmen, reserves are factored in; with the big names, they are not: they thus appear nominally cheaper, and in case of a problem, their legal department handles it at the expense of the client.

Also understood.

That’s nonsense. Make the “effort” to google my reading tip (as a phrase in quotation marks, external links are prohibited here), it is explained there. Neither after phase 1 nor after phase 4 would a cut make sense, and the break between modules A and B is an important “almost phase in itself.” One should also not give the architect a back door to lose interest or “time” at some point in the process. Pay particular attention to two points regarding references (is actually on vacation this week?), namely what his clients say about his price estimation accuracy and his construction supervision.

In summary, it makes sense to conclude 3 contracts with the architect building on each other.
1. Contract for service phases 1 + 2 (Module A)
2. Contract for service phases 3 + 4 + 5 (Module B)
3. Contract for service phases 6 + 7 + 8 (Module C)
After each module, one could change the architect if it doesn’t fit.
An additional construction expert is only useful/recommended when building with architects if there are disagreements between the architect and the craftsmen during acceptance.
Have I understood this correctly?

In summary, it makes sense to conclude 3 contracts with the architect building upon each other. 1. Contract for service phases 1 + 2 (Module A) 2. Contract for service phases 3 + 4 + 5 (Module B) 3. Contract for service phases 6 + 7 + 8 (Module C) After each module, one could change the architect if it doesn’t fit after all. An additional building expert is only useful / recommended when building with architects if there are disagreements between the architect and the craftsmen during acceptance. Did I understand that correctly?

Yes, almost: after the dough resting pause after Model A, one should know whether to continue working with the architect. After that, I would only make a second contract. This may well include a termination option after Module B, but at this point one should basically be clear whether one wants architectural supervision until completion. For first-time building clients, I recommend as the royal path to make the second contract covering Modules B and C (depending on personal distrust temperament, either without or with a termination option after Module B). Whether a building-accompanying expert as a "belt to suspenders" provides redundant double security ultimately probably depends on this attitude. With the captain’s belt Toscanabauhaus with corner windows, walk-in shower, and cantilever staircase, I see it as more necessary than with the Nordlys bungalow ;-)