Gap in sound insulation ?

[foxhole]

Still worth sealing it IMHO

Anything sealing it will be fine .

 

[NorthernLights811]

I think I'll go with the sound proof mastic sealant suggested here, as opposed to expansion foam that I was initially suggested, which I think would do more damage than good.

 

[Leofric]

Still worth sealing it IMHO

Definitely.

 

[Leofric]

Small air gap will have little impact when most of the sound will be transmitted directly thru timbers .

An air gap all the way through a floor between dwellings will have more than a little impact on sound transmission

 

[foxhole]

An air gap all the way through a floor between dwellings will have more than a little impact on sound transmission

Not if it’s tiny.

 

[Tigercubrider]

A 25 mm square hole will allow 15db extra sound through.
Or a 1mm crack 1metre long

 

[catlad]

Surly the acoustic slabs between the floor joists would eliminate light and sound?

 

[foxhole]

A 25 mm square hole will allow 15db extra sound through.
Or a 1mm crack 1metre long

And neither are present .