Has anyone any real world experience of sound proofing a party wall?

Can you give more information on what noise is coming through and what the wall construction is currently?

I used to do sound insulation testing for new builds and conversions, then advise on remedial work if needed. It can be tricky

we had a victorian terrace.

we ended up with pretty much this solution;

was quite effective at reducing ‘incidental’ noise (tv, voices, telephone ringing) to levels that didn’t disturb us but if someone turns their stereo up load enough it’ll come through/around.

it’ll come through/around.

This is your biggest challenge, sound going ‘around’. It’s known as ‘flanking’ in the sound insulation world. Building a panel that reduces sound transmission is straight forward. Installing it to be effective is the difficult bit. The junctions with the existing structure are key

Most people fail to grasp this concept, spend a lot of money on an expensive panel system and then have the sound flank around it

one other thing – you lose 6″ of floor space with the ‘new wall’ thing – we just did the alcoves either side of a chimney so it really just halved the depth of that and wasn’t that much of a problem. Possibly slightly less effective as a result but it did make a noticeable difference to sound transmission – we had a flat next door with their lounge next to our bedroom.

good pic from waswas – you want a mix of low density and high density materials but the resilient bars in the picture and the rock wool are doing most of the job (reducing lower frequency), the panels deflect the higher frequency sound. but as dmorts says, it’s tricky and there will be still some that gets through but it will be occasional and mostly indistinguishable

Its a 1910 semi with a brick party wall – how thick i don’t know. When the neighbours use their dining room and get a bit rowdy I can hear their voices as their dining room backs onto my lounge and vice versa.

I’d heard of people rendering the wall to increase its mass and fill in any gaps in the original mortar etc.

I have worked on acoustic solutions to new builds but never on a refurb which is effectively what this is so I have an understanding of flanking transmission.

I assume it’s solid brick? If you don’t have a cavity, flanking down the external walls may be less of an issue. You need to make sure the new wall goes right up the the brick on the external wall (i.e. strip the wall back to brick where the junction is.)

But, first thing is there a fireplace in that room, in the party wall? Voices heard clearly could suggest gaps somewhere

Move!

We had this, newbuild and the walls were, on the face of it, reasonably well soundproofed. However the sound travelled well through areas of the roof and up cavities meaning when we were in bed we could clearly hear dinner parties and when we were in the next room less so.

Of course in summer when the gatherings can move outside then no wall soundproofing will help.

I’d heard of people rendering the wall to increase its mass and fill in any gaps in the original mortar etc

You won’t increase it’s mass by anywhere near a significant amount by applying render. However filling gaps is good

Is it single storey or two (or more) storey? As there are the floor and ceiling junctions to deal with. What is the floor? Solid or wooden raised?
If raised there’s a possible flanking route there and the new wall would need to go down below floor level (or you upgrade the floor too!)

Similar for the ceiling, you may need to upgrade the ceiling for it to be most effective (e.g. add mass by an additional layer of plasterboard)

We had this, newbuild and the walls were, on the face of it, reasonably well soundproofed. However the sound travelled well through areas of the roof and up cavities meaning when we were in bed we could clearly hear dinner parties and when we were in the next room less so.

If the OPs wall is solid brick this sort of flanking won’t occur. However I have come across your own issue in new builds!

We did ours as follows:

2 x 1 Battens every 40cm
2 layers of overlapped gyproc soundbloc right down joist level
Sealed seams then plastered
Replaced floorboards / skirtings

It’s made a huge difference to the level of noise – our neighbour does band practice with drums several days a week.

Cost wise it was reasonable and we’ve only lost around 6cm room width so barely enough to be noticeable.

I’d imagine its a solid party wall.
Ground floor is concrete (previous owner took up the quarry tiles)
First floor is timber.
I think i can deal with ceiling/wall junction by filling between the floor joists with Rockwool coming back from the wall by around 1000mm.

The house next door is a student let, and they’re actually pretty quiet most years. However, as a proviso we put book cases on that side of the living room wall and they make a big difference. Upstairs we have wardrobes against that side. Not that I care, I sleep with ear plugs so they could party all night and I’d not notice.

have looked into similar solutions myself and may need to again as i’m moving into new place this weekend – it’s a 1960’s semi bungalow which shares a garage void underneath the living room floor in both parties bungalow.

Am worried about attempting to sound proof the party wall (in living room) only for sound to travel underneath and into garage space – utilising the living room floor as an effective drum skin.

I think i can deal with ceiling/wall junction by filling between the floor joists with Rockwool coming back from the wall by around 1000mm.

This sounds sensible, you can always upgrade the ceiling afterwards. Thinking about it, would you be prepared to strip the party wall back to brick? I think there may be gaps and sealing this with a parge coat might give some gains. Then build an independent wall as specified above.