Can you name this brick?

afatbollix

Been having problems finding this brick online.

Our block of flats has been built with it and its sound retention is shockingly bad.

It looks like concrete mixed with straw!

iwillhtfu

Never seen anything like that it looks like plywood. Are you sure it's a block?

Possibly poured concrete that was shuttered with ply leaving that effect

punisher5112

Looks like poured concrete with timber used to seal.

Joeseph Balls

Looks like chipboard

afatbollix

It's deffo a block. Its also not from a mold as the surface is too flat and its got holes from the edges of the wood/straw.


It looks like it's a cheap brick that is full of wood/straw airated to use less material = cheaper block

It seems they didn't even use concrete to join the bricks together and it looks like a foam? Anyone aware of some developers doing that?

iwillhtfu

afatbollix wrote: »

It's deffo a block. Its also not from a mold as the surface is too flat and its got holes from the edges of the wood/straw.


It looks like it's a cheap brick that is full of wood/straw airated to use less material = cheaper block

It seems they didn't even use concrete to join the bricks together and it looks like a foam? Anyone aware of some developers doing that?

That looks like a rubber sometimes used to fill gaps in poured walls.

I'd still say it's a pattern picked up from a ply wood form. There are no blocks like you're describing readily available and certainly apartments aren't built out of them.

Joeseph Balls

Is it an imprint from shuttering?

iwillhtfu

Joeseph Balls wrote: »

Is it an imprint from shuttering?

Or an echo?

afatbollix

Found it its called Hempcrete blocks...

https://www.ukhempcrete.com/

iwillhtfu

afatbollix wrote: »

Found it its called Hempcrete blocks...

https://www.ukhempcrete.com/

Yep they're the ones alright among others but I doubt they built a block of flats out of them. They're more of a bespoke block and would be more expensive than your standard 9" cavity etc.

Where is this block of flats?

afatbollix

London, It's an eco estate so I can guess that's why they used them.


It's only that we can hear everything of next door including the kettle boiling and the microwave!

I found a thesis online by someone in Finland with sound tests and it says it shouldn't be used in houses for sound insulation.
https://www.theseus.fi/bitstream/handle/10024/121363/Hempcrete_Noise_Barrier_Walls_KC.pdf?sequence=1&isAllowed=y

The developer is going to do a sound test for us in the next few weeks but sounds like it shouldn't of been used between the flats. There's 8 blocks all built by the same developer.

iwillhtfu

afatbollix wrote: »

London, It's an eco estate so I can guess that's why they used them.


It's only that we can hear everything of next door including the kettle boiling and the microwave!

I found a thesis online by someone in Finland with sound tests and it says it shouldn't be used in houses for sound insulation.
https://www.theseus.fi/bitstream/handle/10024/121363/Hempcrete_Noise_Barrier_Walls_KC.pdf?sequence=1&isAllowed=y

The developer is going to do a sound test for us in the next few weeks but sounds like it shouldn't of been used between the flats. There's 8 blocks all built by the same developer.

Makes a bit more sense alright.

That sounds like a nightmare scenario alright. It's not uncommon in apartments though to hear your neighbours. There are loads of threads on here about it and wooden floors seems to be a big contributing factor.

No idea of their noise isolation but I can't imagine there's much to be done by the builder to improve it. Unless they retro fit some sort of acoustic board inside but there a few different ways sound transfers or is amplified.

afatbollix

It should meet building specs and we have insurance for it.

We will work it out with the developer after the sound test. If they won't do anything we will go through the insurance company.

Metric Tensor

I have no idea what the UK regulations are for sound transmittance but if you look up Technical Guidance Document E you will find the Irish rules for the amount of sound that should transmit from one apartment to the next. You can use it for comparison with the measured results you get back.

afatbollix

FYI It failed the sound test with a score of 41Db, Pass is 45Db. We are in talks with the developer to sort it out at the mo.

sydthebeat

afatbollix wrote: »

FYI It failed the sound test with a score of 41Db, Pass is 45Db. We are in talks with the developer to sort it out at the mo.

The lower the decibel the quieter the sound???


Do you mean 51 dB?

Outkast_IRE

sydthebeat wrote: »

The lower the decibel the quieter the sound???


Do you mean 51 dB?

Does it mean that when they produced sound at 41db on the other side of the wall it failed the test , and sound up to 45 dB should not be picked up to pass the test ?

Just a guess

afatbollix

They play a white noise at 100Db one side of the wall and it should reduce it by 45Db. It only brought it down 41Db so failed.

ED E

Yeah, attenuation can be written in the positive even though you're "measuring a negative".

3dB is a doubling so the delta is rather significant. What engineer/arch signed off on that without any research?

sydthebeat

afatbollix wrote: »

They play a white noise at 100Db one side of the wall and it should reduce it by 45Db. It only brought it down 41Db so failed.

Ah that makes sense, thanks.