Sound insulation issues in new-build, timber framed, semi-detached house – anyone had similar?
Recently bought a 3-bed semi-detached, and we're having concerns about the sound insulation between us and the adjoining house.
We can hear our neighbours' conversations (although slightly muffled) and general day-to-day activity quite clearly, as well as footsteps. The footsteps are particularly noticeable and can sometimes sound as though they're coming from inside our own house / directly above our living areas.
Our snagging inspector had also raised some initial concerns about the acoustic separation but developed assured were all up to building standard.
I raised it with the developer, who provided us with a SITRI sound test report from other houses in the estate (apparently not all houses need to be tested, only 1 per batch). The tested walls in similar house achieved 56 dB, against a stated requirement of ≥53 dB, so they passed.
The developer also mentioned on the phone that they've previously tested other houses by having buyers go into the adjoining property and talk loudly/shout between the houses, and apparently very little, if anything, could be heard.
That doesn't seem to match our experience at all as mentioned. Pafticually when the neighbours have large groups over.
The developer has now offered to have our specific house tested, but has said we'd have to cover the cost if it passes. The testing company has also indicated that the retest would be limited to assessing compliance with the Building Regulations.
Has anyone here had a similar issue with a new-build semi/terraced house?
Is this level of noise normal even with a 56 dB party wall?
Should normal conversations be clearly audible through the wall?
Could the footsteps be a separate impact/flanking transmission issue?
Would you recommend paying for the developer's test, or getting an independent acoustic assessment that looks at the wider issue?
Any experiences or advice would be appreciated.