Is it sensible to have the construction contract checked by experts from prefabricated house manufacturers (Weberhaus, Schwörerhaus, or Keitel-Haus)? We are more concerned with the technical examination rather than the legal one. Do you also get information regarding the appropriateness of the prices? Who has experience with construction contracts from the aforementioned manufacturers? We have not yet decided on a manufacturer. Favorite is Keitel-Haus. What costs should be expected for the examination? Where can objections arise? Since many things are only decided during the selection of fittings, can this not be checked? Is the contract adjusted again after the selection of fittings?
I consider it sensible if you yourself don't really have much expertise in this area. I also gave my construction description to the expert to review, but without a specific examination order. If he wants to accompany the construction, I found it appropriate that he reviews the construction description and informs me free of charge about noticeable matters and his basic opinion. He did that and also gave a few very helpful suggestions, which I was largely able to implement.
An examination of the construction description doesn't cost a fortune. I would estimate it somewhere around 250 - 300 euros if it is not basically done free of charge. Of course, it also depends on the individual case. If you get a construction description of three pages with colorful pictures, then it will probably be more complex because essentially a usable construction description must first be created from that. Then it might be questionable whether the contractor is willing to accept the many changes. But that is also part of selecting the provider, so that’s completely fine.
Various objections can arise. A common one is the use of general descriptions such as "a stylish washbasin." That would probably mean "the cheapest washbasin you can get somewhere." This happens to all components, and you will not know what exactly in detail will be used for your construction. The main task here is that nearly all services are described in detail (Washbasin Villeroy & Boch, Omnia ballaballa, 60 cm, with single-lever mixer "Wassermarsch" by HansGrohe).
But the execution can also deviate from today's standard. Essentially, private autonomy applies. Almost everything can be agreed upon between the parties. Even one-sided unfavorable contracts, as long as certain limits are not exceeded.
The selection of fittings then provides more clarity here. The details chosen during the selection of fittings should again be recorded in detail. Normally, the construction descriptions provide a certain selection here, and during the fittings selection, you choose something from this selection. Deviating choices regularly mean an additional cost (and upward there are hardly any limits).
Here I can only give the recommendation to be clear about the detailed features BEFORE signing the contract and to negotiate prices for higher-quality equipment variants BEFORE signing the contract. The position for realistic prices is simply better. Once you have signed, the price for extra/better equipment can essentially be dictated. That is rather unfavorable if you want to pay reasonably.
By the way, I don't think much of extortionate negotiations, especially if you value a good and smooth construction process. Everyone has to make a living from their performance, and that also applies to the contractors. Good services regularly cost more than what is charged for mediocre/poor services. Stay away from supposed bargain offers. I don't think contractors will forgo their margin just because you want to build cheaply; therefore, savings will be made elsewhere, and that is often with the craftsmen, who will save on you.
Did I forget anything? If so, just ask.