Inspection/Supplements

I had all prices included in the contract. These were listed in a section called "optional surcharges," so they were not included in the contract price but I could still get them at the indicated price, including sockets. Actually, I was given the prices for everything and they were added upon request.

We also tried to include some things in the contract. Ultimately, so much changes from signing to construction that it is almost pointless.

Surcharges for electrical work were excluded for us, as these were settled directly with the craftsman. We only knew the approximate price for the sockets.
For plumbing, we did have a walk-in shower included in the main contract, but during the plumbing selection, the bathroom layout was completely changed and was finally settled directly with the craftsman. We could have gotten the snow guard from the craftsman for almost half the price per running meter.
Although we had the tiling done by the tiler of the general contractor, we took the trade completely out because the entire calculation of surcharges for installation types, tile sizes, stainless steel edges, etc. was so complex and with the corresponding markup from the general contractor would have become so expensive that direct billing with the craftsman was better for us.
We had the staircase optionally in the main contract, but then had it installed directly by the staircase builder of the general contractor and were billed directly.

Thus, the main contract served as a starting point, but changes always occur during planning and construction.

Small special orders such as the snow guard or additional drywall work I would negotiate directly with the craftsmen in the next construction. They are always cheaper than the general contractor.

We also documented everything. In the end, one position was removed and 10 new ones were added.

With prefabricated house providers, there is often the option to do a preliminary sampling in order to include all (even previously unknown) special requests in the contract. Then you also know what Homeway / electric shutters, chimney flue, etc. cost additionally. For us, the preliminary sampling was very valuable because we then knew what the company's "standard" is and what surcharges we would face. The surcharges were always mentioned (e.g., glass pane in door costs a 100 € surcharge, lockable window handle costs 20 € each, ...).

We have left everything at the standard in the [GU-Vertrag] and simply maintained our own price list and are currently handling all extras (bathroom / electrical) directly with the craftsmen. This is definitely cheaper than in advance in the [GU-Vertrag]. However, you have to have planned the financial reserves for this... Just as an example: for electric roller shutters, we would have paid more than double per window in the [GU-Vertrag] than we do now afterwards...

Thank you for the many responses. It seems to be a trade-off between planning security and savings potential. Currently, we are somewhere in between. Most of you report that the craftsmen offer reasonable prices for additional services, which is already encouraging.

It was different for us.

We had some things measured, for others we followed the advice of the GU and discussed them directly with the trade (e.g. electrical). Often, the GU adds another X% if you include additional sampling separately (although our GU usually held back here).
For the things we had measured separately, our GU occasionally just shook his head and grumbled in his non-existent beard, "We would have done that anyway."