I bought in 2015 an apartment on plan (Belgium). In the specifications it was mentioned that the belgian acoustic standard of 2008 "NBN S 01-400-1" would be respected. I received the keys in November 2017. Since then, I hear a lot of neighbors from below, whatever the room, to varying degrees. The noises that I hear can be of all kinds: words, music, shocks, sound of a powered switch, noise of a roller blind operated, sound of flowing water, sound of a washing machine, ... In particular the noises of the roller blind and switches are as if they came from the same room. I woke up several times startled, thinking there was someone in the room.
I am forced to sleep with ear plugs. Neighbors are co-location students, who can sometimes return on weekdays at 2,3,4h in the morning ... I do not think the apartment meets the standard in force. I interviewed several other residents of the building, none complained of acoustics problems, including the neighbor below who claims to never hear me, and the neighbor upstairs. I is strange because i'm a DJ and ususally mix techno music at high level 2 hours per week.
I contacted the developer, who came to see, and who tried to minimize the problem. After several exchanges, I managed to convince him to organize an acoustic audit, which he would pay if he were to prove positive, otherwise I would pay if it turned out to be negative. The promoter chose the expert (who had already worked for them) The report turned out negative, at the limit of the norm. In hindsight I admit to having made a mistake, I should've hired an independent expert at my expense. I posted a 1 star review on Google Maps, and the developer then contacted me, by phone, to remove it in exchange of half the price of the audit (500€). I refused by email, saying that I wanted a solution to the acoustic problem.
In the meantime, I still have sound problems, and I do not know what to do. I'm asking for your help.
I hesitate to ask a counter expertise because the first has already cost me more than 1000 €. Even if it would be positive, what are my options? The developer may not find the source of the problem? And if so, maybe the work will be too important or will depend on the goodwill of the neighbor? And if the developer pays me an amount in compensation, wouldn't recognizing this acoustic problem make the good unsalable? If I do not do anything and decide to sell, should I give a copy of the first acoustic audit to the buyer, as it is negative ? If this buyer asks me questions about sound insulation, what should be my answers?