We now have several offers for house construction on the table. All of them include site management. In the sales talks, two of them also mentioned that the site manager has insurance. I was always told that the site manager also controls the quality and in the worst case is liable for it.
Here in the forum, however, it sounds more like the site management only takes care of coordination and wants a quick construction completion.
If you plan and build with an independent architect – that is, you commission them for both halves including service phase 8 – then the architect is your contractual partner for planning including site management, and they are required to have professional liability insurance (also covering, for example, that they would not approve botched work).
If, on the other hand, you build with an "included architect" of a general contractor or with planning by an independent architect commissioned only for the first half ("service phase 1 to 4 – beware: these are mostly warns architects!") and then award the contract without a tender to a general contractor, the general contractor will usually tell you that you do not need a site manager at all because a "site manager" is included in their offers. Such a contractor’s site manager does not offer you the same as your architect’s site manager or your construction-accompanying expert. Formally, the "site manager" is also called site manager and is legally so insofar as they act as the signatory for the site manager declaration (i.e., they name the safety coordinator to the building authority and are available as recipient of any possible building stop order).
However, regarding your interest in quality assurance, the site manager (architect’s site manager) and the "site manager" (contractor’s site manager) differ very significantly: namely, your architect acts like a lawyer representing your interests, whereas the contractor’s "site manager" represents your contractor general contractor. Their main task is to be the site project manager. This means they moderate between subcontractors (and, if applicable, the core team of the GC) and chase after delayed or wrongly delivered parts by phone. You are not their enemy (insofar as it does not bother them if their activity also benefits your interests), but in case of doubt, your opponent (insofar as your interests differ from those of their bread-and-butter provider). Their loyalty belongs to the GC, not to you. They are not a contractual party toward you (but only an agent and, if applicable, authorized representative). Whether and against what they are insured is none of your concern and brings you no benefit or additional security.
In an emergency (if botched work occurs), the two differ in that your architect site manager or construction-accompanying expert has as their supreme principle the (re)establishment of the agreed condition, i.e., they will have a defectively executed component torn down and rebuilt. The supreme principle of the contractor’s site manager is, however, entirely different, namely the protection of the GC’s profit against additional costs. They will assess whether the botched work endangers your acceptance of the GC’s services or makes it likely that you will claim the defect within the warranty period. A defect you will not see within five years is, for them, effectively non-existent. The site manager will thus already have a crooked wall torn down again before plastering, while the "site manager" will ensure that it is plastered to look as if it had been built straight. The learning content of the fifth professional year of a "site manager" consists of memorizing the thousand cheekiest "That doesn’t matter" lies – the main thing is that you do not withhold any money.
I was always told that the site manager also controls quality and in the worst case is liable for it.
Yes, but not in your favor. They are liable
toward their employer for the additional costs if they culpably do not reject defective delivered material in time and/or are responsible for the correct replacement delivery being delayed.
In the sales talks, two of them also mentioned that the site manager has insurance.
You can therefore immediately throw the offers of these tricksters in the round file (and remember to recommend them only to people you wish plague).