Is membership in the Association of Private Builders worthwhile?

We are currently building our first house and I am actually considering canceling our membership due to lack of added value. You always have to commission the expert separately on a fee basis anyway, so I wonder why I should first join the association. There was once a letter with welcome etc. and the invoice. Since then, nothing more has been heard.

For the shell construction inspection, we then commissioned an expert. There was an offer showing what costs what, etc. We accepted it and carried out the inspection. Fortunately, there was nothing serious, but rather more flaking on the brick walls or gaps that were too wide. Well, you can't change that anymore, only repair it. Regarding the membranes, they wanted to know exactly what brand it was and whether it was approved for the purpose. The site manager was supposed to provide proof for that. Some points were only noted, such as fire protection being present, insulation installed, the wall being made of sand-lime brick, etc. I don't know why that was done, maybe because otherwise we would have had too few points on the list??
What really bothered me, however, was the procedure that after the feedback and repair of the defects from the site manager, I received a request that everything would now be entered into a "database" and the expert would comment on everything again. For that, I would have to commission separately again and pay according to the fee rate. We didn't do that anymore because a) if I receive photos showing that the defects have been fixed and data sheets for the membranes, then from my point of view that's enough. Why spend money on someone typing it up and saying "it's okay" again?
But our main concern was to know that there are no serious defects and not that everything is neatly stored in some database.
Another point that bothers me is that, for example, we have a dispute with our site manager regarding the front door. In our opinion, it is not as promised and communicated beforehand. He says I ordered what you told me and with that, I'm out. But we see a certain duty to clarify when something obviously does not turn out in reality as we imagine. The expert noted this point, wrote down what we told him, and that was it. The reaction of our site manager to this point was that the matter is settled because he only did what we wanted. We had read the properties of the door.
Afterwards, I prepared the communication etc. and sent it to the expert because he wanted it. Only upon inquiry did I learn from the secretariat that he had just skimmed it and if he should familiarize himself with it, I should commission him. Ok, thanks for nothing. Not a finger is lifted without payment. I can basically understand that, nobody works for free, but 180 EUR an hour for reading and why am I even in an association? I would have expected that you can call briefly with a question, but you can't get past the secretariat without commissioning.

The next inspection is coming up and I am looking around to see if we can find someone else.

For the shell construction inspection, we then commissioned an expert. There was an offer about what costs what etc. We accepted that and carried out the inspection. Fortunately, there was nothing serious, but rather chipping on the brick walls or too wide gaps. Well, that can no longer be changed, only repaired. For foils, they wanted to know exactly what brand it is and whether it is approved for the purpose. For that, the site manager was supposed to provide evidence.

Currently, the next inspection is coming up and I am looking around whether we can find someone else.

Another point that bothers me is that, for example, we have a dispute with our site manager regarding the front door. In our opinion, it is not as promised and communicated beforehand. He says, I ordered what you told me and with that I am out. But we already see a certain duty to inform if something in reality obviously does not turn out as we imagine it.

Do defects have to be documented in case of a legal dispute? So in the sense that it was professionally fixed, otherwise tacit consent?

So you only brought in an expert for a visual inspection of the "fallen cubes" after the respective construction phase was completed, instead of using one throughout the construction?

They are a defect, in my opinion even a serious one, but not really one that would only arise during execution. When advising clients I already circle such critical points during plan review, so the construction-accompanying expert can put them on his list right away. Prevention is always more efficient than later nitpicking - therefore, I generally recommend an accompanying expert rather than a "damage assessor." You should use him as a site manager - also and especially if you have a contractor "site manager."

Layperson training / product selection advice is neither a task of a "site manager," nor would it be among those of a site manager without quotation marks. What is the issue: did you have wrong ideas about what "(one-sided) overlapping" means for a door leaf or similar?