Gap in sound insulation ?

[NorthernLights811]

I have sound insulated my wooden floor using MuteMat 3 and the flanking strip that comes with it.
However my contractor left a part which is not part of the wall (therefore there is no skirting board) that touches the wardrobe without the strip, and I realized the other day that there is light coming from the bottom floor's ceiling.
My guess is that (airborne) sound escapes from there too.
He suggested to use self expansion foam to cover the gap, and that he couldn't put the strip as there is no skirting to fit on top.
I am not sure on the self expansion foam, first I don't think it can replace the sound proofing strip, and second I am afraid that it will push the rest of the floor up in that area.

Any suggestions how to tackle this? My main worry is that sound might be escaping from there to the floor below.

 

[foxhole]

Careful escaping sound can be very dangerous.

 

[NorthernLights811]

Careful escaping sound can be very dangerous.

It's not JUST that, it's that we don't want to disturb the people below. And having invested a lot of money in sound proofing, that would be silly.

 

[Tigercubrider]

A small hole in soundproofing will allow a great deal of noise through.

 

[NorthernLights811]

A small hole in soundproofing will allow a great deal of noise through.

That's what I was told. Any suggestions to fix this particular problem?

 

[Tigercubrider]

A soundproof wall 10x10 feet with a 1" hole will be reduced in efficiency by 30%

You need something like a proper mastic.

 

[Tigercubrider]

https://www.soundstop.co.uk/ZAMAS33...RTQqEL0WltvHu6sf4OtXVVyd7l3aaDjRoCu7QQAvD_BwE

 

[NorthernLights811]

A soundproof wall 10x10 feet with a 1" hole will be reduced in efficiency by 30%

You need something like a proper mastic.

This is probably 5mm on the floor and about 1-2mm on the plywood underneath.
Link to the proper mastic please? Will that do for the sound insulation ?

 

[NorthernLights811]

These guys charge £25 for delivery! Wow..
Would any of these do?
https://www.sealantsonline.co.uk/Products/Acoustic-mastic-sealants
Or this?
https://www.amazon.co.uk/Everbuild-AC50C4-Acoustic-Sealant-Adhesive/dp/B0012RLYJ6

 

[Leofric]

It's not JUST that, it's that we don't want to disturb the people below.

Is this a floor between two dwellings How has a clear gap right through the floor come about Might be more than just an acoustic sealant required.

 

[NorthernLights811]

Is this a floor between two dwellings How has a clear gap right through the floor come about Might be more than just an acoustic sealant required.

Correct, it's between 2 floors.
The stack consists of 200mm joists, floorboards,
Mutemat, plywood and engineered floor.
At this particular point, a wardrobe is placed on top of the floorboards.
My guess is that there was an existing gap in the floorboards, which coincided with the rest of the stack (sound insulation, plywood and floor), and therefore the light comes through.

 

[foxhole]

With solid floors in what seems to be dwellings not designed for multiple residents then sound transmission will always be problem , carpet over thick underlay would be best floor surface .Small air gap will have little impact when most of the sound will be transmitted directly thru timbers .

 

[NorthernLights811]

With solid floors in what seems to be dwellings not designed for multiple residents then sound transmission will always be problem , carpet over thick underlay would be best floor surface .Small air gap will have little impact when most of the sound will be transmitted directly thru timbers .

Agreed, but to be fair, we replaced the original carpet with no underlay, with strong underlay and engineered floor. I am aware of the airborne and impact noise topics, which I won't expand here, my original post is around airborne sound transmission around an air gap (as opposed to carpet with the same air gap, without sound proof underlay).

 

[foxhole]

Agreed, but to be fair, we replaced the original carpet with no underlay, with strong underlay and engineered floor. I am aware of the airborne and impact noise topics, which I won't expand here, my original post is around airborne sound transmission around an air gap (as opposed to carpet with the same air gap, without sound proof underlay).

Very little airborne noise thru a small slit .

 

[NorthernLights811]

Very little airborne noise thru a small slit .

Still worth sealing it IMHO