Soundproofing Party Wall & under floor

[Smalltowngirl_95]

We have recently bought a 1930s semi-detached house which we believe has double skin party wall. However, we can hear all types of noise such as dogs barking, sneezing, television and shouting.

We have already installed a soundproof system directly in front of the party wall which consists of 50mm acoustic insulation and a double layer of acoustic plasterboard framed out.

However we can still hear a lot of noise which makes me think it is now coming up through the floor? Our floor in our living room/dining is a timber suspended floor. Recently had new double glazed UPVC windows installed too.

Would we need to take up our floorboards in the living room/bedroom and put in insulation? If so would we need to do all the floor or ideally come out a metre or so? I'm not sure if there is gaps as well where the joists run into the party wall.

Any help/advice would be greatly appreciated as it's having a negative impact on our day to day lives.

 

[endecotp]

Which way do the joists run?

Don’t expect miracles.

 

[accelerator]

Would we need to take up our floorboards in the living room/bedroom and put in insulation? If so would we need to do all the floor or ideally come out a metre or so? I'm not sure if there is gaps as well where the joists run into the party wall.

It's likely that the suspended floor is causing an issue.

You'd need to do the whole floor, 1m out would still leave a lot uninsulated, so no real difference.

I'm sure there'll be a lot of info online if you look for it.

 

[StephenStephen]

It's likely that the suspended floor is causing an issue.

You'd need to do the whole floor, 1m out would still leave a lot uninsulated, so no real difference.

I'm sure there'll be a lot of info online if you look for it.

I'm wondering if there might be a misunderstanding here about the direction the sound is travelling.
Is it that the sound is coming sideways from rooms in the house next door?

 

[Smalltowngirl_95]

Which way do the joists run?

Don’t expect miracles.

The joists run into the party wall

 

[Smalltowngirl_95]

I'm wondering if there might be a misunderstanding here about the direction the sound is travelling.
Is it that the sound is coming sideways from rooms in the house next door?

The sounds can be heard directly from the party wall even though we have built an independent false wall Infront. I am now wondering if the sound is now coming up through the floor rather than the new sealed wall.

 

[JohnD]

The joists run vertical into the party wall

I'm pretty sure the joists will be horizontal.

 

[Smalltowngirl_95]

I'm pretty sure the joists will be horizontal.

If I am looking at the party wall the joists run vertical into it.

 

[JohnD]

Not trying to be rude, but that's not what "vertical" means.

 

[JohnD]

Have you got fireplaces on the party wall? Are they bricked up?

 

[Smalltowngirl_95]

Not trying to be rude, but that's not what "vertical" means.

Sorry John I can see now what you mean. To confirm the joists run into the party wall. I am unsure if there is gaps around where the joists run into the wall which needs to be sealed to block the noise?

We have already renovated the whole of downstairs so ideally need to take the floor up without disturbing or making a mess of things.

 

[Smalltowngirl_95]

Have you got fireplaces on the party wall? Are they bricked up?

We dont have a fireplace, this got completely removed 20+ years ago before we bought the house

 

[JohnD]

Was the chimneybreast removed?

 

[Smalltowngirl_95]

Was the chimneybreast removed?

Yes it was completely removed from downstairs

 

[JohnD]

Yes, the joists are probably pocketed into the brickwork, and there are probably gaps. You would to take up at least some of the floorboards for access. Clean out loose material by scraping and using a builder's canister vacuum (not a domestic vac). You can pack them with sand and cement mortar but you will probably find expanding foam easier. Remove all the dust and spray the hole with water to make it stick. Use the plastic extension tube to get it deep into the hole. I use the pink fire foam which blocks smoke and flame, it chars but does not burn. Most likely you will never have a fire, but, why not?

In some cases there is a separate sleeper wall just inside, but I think I have only seen that on exterior walls where it protects from damp.

Gaps in the brickwork are worse in unplastered areas ( plaster hides them ) between floors and sometimes inside cupboards. Builders traditionally used the best bricklayers for the exposed external walls at the front, and hidden brickwork is often very shoddy.

Afterwards, you can pack between the joists with dense mineral wool which muffles noise (loft insulation is much lighter, so not as good).

The relevance of the chimneybreast is that the wall, between your fireplace, and next door, may be very thin, just a flue, and this is not as good for blocking sound. If it was just plastered, plaster is less dense and not as effective as dense thick brickwork.