Hello NUISETTE,
with the signature of the structural engineer, you probably mean the form "Declaration of the installer of structural evidence" for the simplified approval procedure, I assume. This does not yet mean that the work of the structural engineer is finished. It only means that the evidence to be prepared by him complies with public building law and does not necessarily have to be checked by the building supervisory authorities. This also means that the corresponding inspection fee is waived for the builder.
So I would assume that the structural engineer will also invoice the due fee after completion of his services (structural safety evidence including plans and lists, possibly energy certificate, etc.).
If no written architect contract has been concluded so far, there is probably still a contract agreed upon – even if only verbally – according to the Building Code. In this case, the minimum rates of the HOAI apply to the architect's services.
The construction costs vary regionally, but here I calculate with an estimated value of €275 per m³ of enclosed space, since, as you say, it is a hillside location and probably at least part of the lower floor can be used for residential purposes.
This results in a finished construction sum of (930m³ x €275/m³ =) €255,750 gross.
The chargeable net construction sum thus amounts to around €215,000.
According to §16 HOAI, Zone III, minimum rate, an architect’s fee for all basic services across all service phases results in €23,024.20 plus VAT.
As you describe, he has so far worked through service phases 1 to 4 (basic evaluation, preliminary planning, design planning, and approval planning). These four service phases together amount to (3% + 7% + 11% + 6%) 27% of the total fee, i.e. €6,216.53 plus VAT.
If the execution planning (service phase 5) is also already completed, this results in a claim of (27% + 25%) 52% of the total fee, i.e. €11,972.58 plus VAT.
Normally, this should also be apparent from the architect’s invoice, if only to avoid any uncertainties (mistrust).
For determining the structural engineer’s fee, the net shell construction sum is taken here; I assume 45% of the finished construction sum.
The chargeable net shell construction sum thus amounts to ( €215,000 x 45% =) around €96,750.
According to §65 HOAI, Zone II, minimum rate, a structural engineer’s fee for all basic services across all service phases results in €9,502.17 plus VAT.
Which services of the architect and/or the structural engineer have actually been rendered so far cannot of course be judged from here. Therefore, the above fee calculation can only be regarded as a guideline.
To what extent the mentioned changes will additionally affect costs, I also cannot yet assess. For this reason, I have not included them.
In case of uncertainties, I would therefore always first seek a calm and clarifying conversation. The collaboration between a builder and his architect/structural engineer should always be based on full trust, similar to that of a lawyer, doctor, or tax advisor.
Why it should now be said: "building causes grief," I have not heard this saying before and cannot comprehend it from my experience.
On the contrary, the building process has actually brought my clients a lot of joy throughout, and I can say this without any qualms.
I would be interested in comparing your architect’s cost statement with mine. However, as mentioned, it depends on which area of Germany you live or want to build in.