Just before signing a contract with a construction company, what should be considered?

Flightradar can display flight movements historically. Otherwise, these noise maps by airport also help. I believe there is also a nationwide portal on the internet where you can have something like this generated.

There are also two or three Antonov 124 stationed there, I think they won't be very quiet either.

They also reach about 300 starts per year.

Typically, departures in Leipzig head west due to prevailing weather conditions. In other words, nothing taking off is done over Lindental. The approach is more like "gliding," and it starts long before the runway in a straight line.

However, when the wind shifts and departures head east, it's a different story. The keyword is "southern turn":

The short southern turn is a flight route only used during the day (6 am to 10 pm) when there is east wind (on average about one-third of the days in a year). DHL does not need or fly this route. In five months – from November 2016 to March – there were about 650 flight movements on this route – which corresponds to around five percent of all departures or about 130 starts per month.

And this southern turn goes almost "over" Lindental.

So rather imagine going onto the property at night, that could be much more exciting.

And also during the day with east wind... That will be even more exciting.

flightradar can display flight movements historically. Otherwise, these noise maps by airport also help. I believe there is also a nationwide portal on the internet where you can generate something like that

Try this one from the German Air Traffic Control:

stanlytrack2.dfs.de/webstart/EDDP/launch.jnlp

There you can see exactly the departure and approach flight routes for Leipzig. Don’t be afraid of the Javascript. It’s okay.

: Sorry, I had forgotten that even links to public institutions are not allowed here. I used the tool out of curiosity to plot the flight paths from the day before yesterday. Flights were going in both directions and some go out over Lindental. So it won't be completely quiet there.

Does it really have to be in the city? The Leipzig surrounding area is very well connected and you can usually still get plots from the municipalities without a developer at moderate prices. Otherwise, I can gladly recommend someone with expertise who can take a look at the construction service description and the contract.

Regarding the chimney price: We paid around 5000 for the chimney (flat rate length for 2 floors). However, that was in 2013 without [Bodentreppe] or [Druckwächter]. The latter should cost around 700 with the electrician. Therefore, I can well imagine the price of 9000 nowadays all in. Best regards in brief