The bank may want a construction service description despite individual subcontract awarding

Nice to hear that "our" approach is not wrong and that you have positive things to report.

I would say that the approach is the right one, that suits you and leads to the goal. At least I did not mean that "our" approach is more correct than another, or especially yours :-)

But I also believe that using existing offers as a basis for evaluation & approval is definitely better than a signed €/m³ estimate by the architect.

Under the premise that it is also built accordingly, perhaps. Experience shows, however, that in the dynamic design process there can be frequent shifts, so that the basis for the offer changes. For example, you remember that you want another window, which may require changes to the statics, possibly requiring a beam. Suddenly, some controlled residential ventilation pipes can no longer run where you would like them to, because they would cross the beam. On the basis of which steel quantities, which controlled residential ventilation components, which window (dimensions), etc. were the offers then made, and what significance do they still have?

Another example: One wants, since budget-wise after assigning the shell construction and roofer it is still feasible, a KNX bus system, which entails significantly more cabling effort. The ventilation pipes limit the routing of the empty conduits or these can no longer be laid in the concrete ceiling, but on the shell construction ceiling. This possibly makes a different floor structure with liquid insulation necessary -> different cost structure.

You try to be as precise as possible in the specifications to have cost control. It is no coincidence that different levels of accuracy for cost estimation, calculation, and determination are required according to HOAI and the service phases.

At the end of the day, only what works for you personally counts :-)

Then we are basically (if I read your signature) only 10km-20km apart. So it would be interesting to check where we (you and I) stand price-wise or differ from each other :-)

Oh, that’s interesting. You live "where it’s nice," so in Fürth? [emoji6][emoji23]

Yes, it would surely be interesting, but probably also depends a bit on the building project [emoji4]

I would say that the approach is the right one, that suits you and leads to the goal. At least I did not mean that "our" approach is more correct than another, or specifically yours :)

Under the premise that it is then actually built that way, maybe. Experience shows, however, that in dynamic design there can often be shifts, so that the basis for the offer changes. For example, you realize that you want a window there, which may require changes to the statics that might require a beam. Then some controlled residential ventilation pipes can no longer run where you would like them to, because they would cross the beam. On the basis of which steel quantities, which controlled residential ventilation components, which window (dimensions) etc. were the offers then created and what relevance do they still have?

Another example: One wants a KNX bus system, as after awarding the shell construction and roofer it is still budget-wise feasible, which entails significantly higher wiring effort. The ventilation pipes restrict the routing of the empty conduits or they can no longer be laid into the concrete ceiling but on top of the shell ceiling. This may require a different floor structure with liquid insulation → different cost structure.

One tries to be as precise as possible in the bills of quantities in order to have cost control. It is no coincidence that different accuracies of cost estimation, calculation and determination are required according to HOAI and the service phases.

At the end of the day, only what works personally counts :)

Interesting examples: We don’t need this flexibility, why would we, everything fundamental is pre-planned. Upgrades for bathrooms and electrical as well as tiles are buffered.

But if you put such "eggs in the basket" for your architect where, for example, because you decided on the tiled shower only after the screed was laid, then the screed can only be "broken out" at that spot. So some fundamental aspects should already be fixed. Whether you want KNX is clear beforehand anyway. The later you intervene in the planning, the more expensive it becomes.

Oh, that’s exciting. You live “where it’s beautiful,” so in Fürth? [emoji6][emoji23]

Yes, it would definitely be interesting, but it probably also depends a bit on the construction project [emoji4]

No, I live about 20 km around Fürth. It’s nice there :-)

We can exchange via the "conversation function" if you want.

But if you put such "eggs in the nest" for your architect, where maybe, because you then decided on the tiled shower after the screed was laid, the screed can only be "ripped out" at that spot. So some basic aspects should already be fixed somewhere. Whether you want KNX is clear beforehand. The later you intervene in the planning, the more expensive it gets.

Maybe we are talking past each other. I am talking about changes during the execution planning, i.e., the phase in the house building project where the detailed planning is done. And there are a lot of ideas that you balance with the (remaining budget), so you use the feedback/information from concrete tenders to react “very agilely” to the changing requirements. I have experienced this phase as an iterative design process and feel more comfortable with it than with a waterfall-like up-front planning with some “buffers.” And about KNX. No, precisely not. It is a not insignificant cost factor, just like an air-to-water heat pump or a brine-to-water heat pump. I decide dynamically according to budget, and of course early enough not to cause additional costs. But everyone as they like, I just feel more comfortable with adaptive approaches that respond to changing realities than with waterfall-like planning with buffers...maybe also because of my profession. [emoji6]

:-) Seems so.

Even though my concerns were not addressed, it was interesting in the thread. I will get in touch if no construction service description is needed.