Noise problem in new semi!

[Vizsla]

Your post is quite difficult to read. If I understand correctly the developer carried out an airborne test, that passed, but didn't carry out an impact test. Why is that? Impact tests aren't unusual. Any bona fide sound tester should be able to carry one out.

The question really though is how was part E satisfied under the original build and regulations application? You need to find this out? Was it satisfied by testing or by robust detail? Also, is this a one off development of a couple of houses or is it part of a large estate?

Hi it is built to robust details of which I asked for a copy of but there seems to be a few variations in the documents, the house is part of a estate around 100 houses and nearly every semi has complained to either the builder or some have even called police to complain

 

[jeds]

It's a question of matching the robust detail with the actual detail built into your house. If you can show the house was not built correctly you have a good case. It won't be easy. You may need to cut some holes in plasterboard and maybe even hack off some plaster or even drill cavities to find out. If it is unclear exactly which detail the house was designed to it is still worth knowing what has been built because you may be able to show that it doesn't comply with ANY robust detail.

As limerock said earlier, in practice robust details are unreliable because they are rarely built correctly. A year or two ago I had about twenty houses on a 200+ estate tested on behalf of a large developer and only about half passed and then only just. I've designed sound systems for new build and flat conversions for years under the testing procedure and every one has passed with flying colours. So it's not difficult to achieve.

 

[Vizsla]

That's great thanks, il try and get my head around the robust details.
Don't suppose you can think of anything that could be leading to the problem, I realise there a multitude of different things to take into acount but just wondered if there's anything obvious that could cause such a big problem a cross a lot of houses
Thanks

 

[jeds]

Very hard to say. Incorrect block. Incorrect wall ties. Poor detailing of built in floors. Poor filling of perp joints. Some systems are designed to have a render layer and a dot and dab layer - often the render doesn't get done. Others are just dot and dab but with acoustic board - it's common for ordinary board to be used instead. (acoustic board is blue) Some systems have mineral wool in the cavity - which can get left out. Some systems are solid wall - the density of the block is important.

If I had to take a punt, I'd say it's most likely gaps in the separating wall. Perp joints or gaps around floor joists. There's an old rule of thumb; 90% of sound travels through 10% of gaps. So gaps are bad.

 

[Vizsla]

Thanks again this is great help, there still building on our site so I had a nosy expecting to find pour standards but it semp quite good there were no obvious gaps, all insulation in place according to details it's isover rd party wall roll, they hadn't put sealing around the joist were they enter but I have since done this and it's made no difference, there should be a 75mm cavity, 9.8 kg/m2 gypsom board on dabs but they havnt done a solid ribbon as I went in the loft with a rod and could poke it down in many places also the daps are to far apart, there no render parge coat required in the details and the block density says 1350-1600kg/m3 or plasma aglite ultima, they apar to be concrete and not thermolight though,
Il try to find more details but hope this helps, this is realy appreciated

 

[Vizsla]

The other interesting thing is we don't hear any airbourne type noise like talking etc and they claim it passed the airbourne test mid 50s which is quite high ?

 

[limerockconstruction]

We usually put a render sound coat on before dabbing the acoustic board on. They are likely to be concrete for density, but there are alternatives on the market.

If im not mistaken, a solid 215 wall with sound coat and acoustic board will still pass robust details for a semi.

 

[Vizsla]

They havnt used soundproof plasterboard!

 

[Vizsla]

Block wise they seem to be the dark grey almost black when wet and a little crumbly unlike the normal light grey colour block that are more solid if that helps

 

[jeds]

Attenuation of impact sound is about separation. Look closely at junctions and anything that connects one side to the other. Wall ties for example. Are they using acoustic grade ties? Another possible is the cavity might be full of crap.

 

[Vizsla]

Ok thank's il try to find out, presumably if the problem is wall ties or crap in cavity there is little can be done now?
Again many thanks your the first person in 6 months who's been able to help us

 

[Vizsla]

Just a thought with regards to debris build up In The bottom of the cavity, this could make sense as the noise is much worse on our side and our house is slightly lower than next door so presumably the rubble would be touching our wall but not there's as there higher
Can something like this have such a massiv effect on impact noise
As I'm aware it is a fully filled cavity so you wouldn't think much mortar would be able to drop to the bottom
Thanks

 

[Vizsla]

Just an update, realy hoped I was on to something but I removed my meter box from the wall to get access to cavity and it apears to be ok from what I could see, all insulation in place, brick ties clear of mortar and no mortar builds up in the bottom, so I'm bit disappointed in a strange way. Another idea I thought is what if any of the joists that go into the party wall are too long and touching the opposite house wall
Thanks for any help

 

[Vizsla]

Any help or tips would be great, thanks

 

[limerockconstruction]

I'm afraid from here on you really need some on site help mate - theres only so much guesswork that can be provided on a forum like this.