How many years is the post-liability period for "construction all-risk insurance"?

I hope I am in the right subforum here. I did not find anything during the search. I also have the impression that "somehow" many posts have disappeared.

Among other things, we will take out a "Bauleistungsversicherung" for our prefab house purchase, which we are also obliged to do according to the terms and conditions of the prefab house manufacturer. The liability period after completion is explicitly mentioned in the requirements. For how many years of liability period after completion have you taken out insurance?

By the way, the insurance offer was only extended to include the liability period after completion upon my inquiry. So it does not seem to be a standard, at least with our insurance, but it sounds very good to me. (Example: months after moving in, it is found that the main pipes are clogged. The cause cannot be determined (tile layer, basement builder, playing children …). Without the liability period after completion, the insurance no longer covers it because the clogging occurred during the construction period. With the liability period after completion (e.g., up to 1 year), the insurance would still have to pay.)

In principle, you are right, but I would phrase it the other way around: During the extended liability period, the policyholder has the opportunity to prove to the insurer that the cause of the damage occurred during the construction phase (i.e., within the regular term of the policy). Conclusion: if the damage occurred during the extended liability period and its cause also occurred during the extended liability period, the insurer will rightly refuse. The longer the extended liability period runs, the more difficult it becomes to demonstrate that the cause of the damage fell within the regular term of the policy.