Soundproofing Nightmare.....

[phughson]

Hi Guys,

As the title says I am having a nightmare with soundproofing.

House situation:

A good few years ago the cellar was converted into a granny flat. After buying the house in Jan and the granny flat lying empty, I decided that I would get it setup for renting out. However, when I was in the granny flat the noise was just too much that I felt that I could not rent it out. I have both types of noise travelling down from above, airborne and the kids running thumping along the floors.

So, I decided that I had to do something about it. I removed all the plasterboard and old rockwool insulation. As the house kit was 9" joist I put in 2 x 100mm knaf acoustic insulation and 12.5mm db plasterboard 33KG per sheet. It really has made no difference at all.

Where is the noise most likely travelling through? Could it be coming down through the walls? Or, am I best to lift all the carpets and install some type of acoustic underlay/matting?

At this rate it will be a couple of years rental income to pay for the work so far!!!

Any advice would be appreciated.

Thanks in advance,
Paul

 

[Deluks]

Acoustic underlay will help, resilient bar on the underside of the floor joists before adding the plasterboard will help even more. No downlighters or other holes in the ceiling.

What flooring is under the carpet?

 

[freddiemercurystwin]

Insulating existing building buildings is undoubtedly a right royal pain in the backside.

Did you uses resilient bars to hang the plasterboard off? Ideally a completely independent ceiling would have been fitted, ie off new ceiling joists spanning from wall to wall so not touching the existing joists. And two layers of plasterboard with staggered joints. every single possible tiny crack and hairline gap you can possibly find should be sealed up with acoustic sealant. That includes in the floor finish above so under skirtings as well etc

For the floor finish you could go with a proper resilient layer (not just some carpet underlay) and then a floating sheet floor above that ie 22mm T&G plywood for example. that has associated problems of course in terms of raising door bottoms and possible skirtings etc. A good thick underlay and thick carpet is always going to help.

Unfortunately noise will still be travelling through the structure and any other weak points, ie out the ground floor window and in through a cellar level window. Sound is a funny thing, sometimes you can throw thousands at it and it seemingly makes little difference.

 

[phughson]

Thanks for you responses guys.

Deluks:

I never fitted the resilient bar as the gentleman at the store said it was basically a waste of time due to the fact that it is still directly to the joist and plasterboard.

I removed the down lights and now only cables coming out for ceiling roses. Underlay, is a very thin spongy type material ‘square type patterns’.

Another issue is that when I moved in I knocked the wall between the old dining room and kitchen to create one room ‘and as I write this I am sighing’ fitted solid oak flooring with a 6mm underlay mats. Directly below this room is the granny flat kitchen/living room. Needless to say you can’t just hear noise you can hear conversations.

Insulating existing building buildings is undoubtedly a right royal pain in the backside.

freddymercurystwin:

As I talk the roof is getting filled with acoustic sealant and getting tape and filled.

It there a good resilient layer I can use as an underlay so not to raise my floor level too much to effect door heights etc???

Never realised how much of a nightmare sound travel can be. Even to the extent that I do not think even after throwing thousands of pounds at it I will be able to rent it out.

To top it off a joiner put a screw through a cooper pipe and flooded one of the granny flat rooms………… surely it can only get better haha

Thanks again guys,
Pau

 

[Porque223]

You also need to know the spectrum of the noise; traffic noise and speech and walking all have different spectrums and there are materials designed to block the frequencies in the spectrum you wish to block.
Even if you could rent the equipment, a microphone and audio spectrum analyzer, this is probably not a DIY task.

At the high tech end there is active noise cancellation.

 

[indus]

You also need to know the spectrum of the noise; traffic noise and speech and walking all have different spectrums and there are materials designed to block the frequencies in the spectrum you wish to block.
Even if you could rent the equipment, a microphone and audio spectrum analyzer, this is probably not a DIY task.

At the high tech end there is active noise cancellation.

Are you for real??

 

[Porque223]

'Fraid so.

If you're lucky, somewhere in this search
http://www.google.com/search?client...abstract+frequency+spectrum&ie=UTF-8&oe=UTF-8
you can find how somebody in the UK solved a problem just like yours.

The more search terms you add, the more specific and narrow and useful your search becomes, in principle.




You're welcome.

 

[indus]

'Fraid so.

If you're lucky, somewhere in this search
http://www.google.com/search?client...abstract+frequency+spectrum&ie=UTF-8&oe=UTF-8
you can find how somebody in the UK solved a problem just like yours.

The more search terms you add, the more specific and narrow and useful your search becomes, in principle.




You're welcome.

Life would be very simple if every problem could be solved by a google search and attention to search criteria. Even better if one can then regurgitate it to others as though it is knowledge gained through experience or training.

Firstly you need to understand the question and then you need to make sense of the information that the internet throws up.

No offence but I think you have failed on both accounts.

 

[Porque223]

Then perhaps I can redeem myself by warning the OP about a trap that many fall into.

"In economics and business decision-making, a sunk cost is a retrospective (past) cost that has already been incurred and cannot be recovered."
". . .only prospective (future) costs are relevant to [a soundproofing] investment decision."

I.e, What to do now? - for example, do not put any more money or time into this project and instead study up on how others have solved this.
Solving by trial and error doesn't count because you may not know why it worked.
Experience counts providing you have correctly interpreted what you observed.
Competent training & education always counts.

 

[tony1851]

Thanks for you responses guys.

Deluks:

I never fitted the resilient bar as the gentleman at the store said it was basically a waste of time due to the fact that it is still directly to the joist and plasterboard.

Wrong. Resilient bars are useful in that they help break the rigid path between joist and plasterboard. In flexing slightly, they interfere with the frequency of the sound coming through.