Author Topic: Independent ceiling built but still hear impact noise  (Read 4269 times)

max86

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Independent ceiling built but still hear impact noise
« on: September 18, 2014, 03:36:11 PM »
Hi,

I have just had an independent ceiling built and I can still hear impact noise (no airborne though) from and upstairs flat.
The construction was joist 40cm apart with a 10cm of mineral wool  laying on top of it (tightly packed)with a 5 cm gap from existing ceiling. 2 layers of acoustic plasterboard were added and acoustic mastic was used, finished with a layer of plaster.

The profile of it is roughly 5cm of air,10cm of mineral wool, 10cm gap between joist and 2 layers of acoustic plaster board.

Although most pictures show the wool between joist, the builder has put it on top of the joist. I would like to know if this is wrong or possible solutions to it. I understand my flay was converted before any building regulation came in as it is a Victorian townhouse.

Randy S

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Re: Independent ceiling built but still hear impact noise
« Reply #1 on: September 18, 2014, 03:37:54 PM »
did you plaster coat the ceiling and make the hard connection to the walls? or do you still have the 1/4" gap around the perimeter?


Randy S.

Randy Sieg

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888-942-7723
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max86

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Re: Independent ceiling built but still hear impact noise
« Reply #2 on: September 18, 2014, 03:45:37 PM »
There edges were sealed with acoustic mastic and the coat of plaster is going on today. Surely I should be able to notice a difference without the plaster on?

Randy S

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Re: Independent ceiling built but still hear impact noise
« Reply #3 on: September 18, 2014, 03:51:46 PM »
Yes you should be able to notice a change in impact noise if the new ceiling is completely isolated from the floor/ joist system above.
How did they mount the new ceiling joist?
C hangers on the walls?

I would advise holding off on the plaster coat for now.

If you can Give me a call direct and lets discuss this.

Randy S.
760-752-3030 ext 104
Randy Sieg

Super Soundproofing Co
www.soundproofing.org
888-942-7723
Ph. 760-752-3030
Fax.760-752-3040

max86

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Re: Independent ceiling built but still hear impact noise
« Reply #4 on: September 18, 2014, 05:12:46 PM »
yeah he used c hangers. I am worried the cavity between the joist is acting like a 'speaker box'. Cant really ring as i am based in th UK.

Randy S

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Re: Independent ceiling built but still hear impact noise
« Reply #5 on: September 18, 2014, 06:08:16 PM »
ok, a couple things could be happening here.
1) not enough insulation and mass to absorb and contain the impact noise with in the cavity.
2) the C hangers are too close to the original joist system which allows the impact noise to get back across the new ceiling system.
3) if the original ceiling was lath and plaster and the perimeter was not cut and filled with acoustical caulk.

Randy S.
Randy Sieg

Super Soundproofing Co
www.soundproofing.org
888-942-7723
Ph. 760-752-3030
Fax.760-752-3040

max86

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Re: Independent ceiling built but still hear impact noise
« Reply #6 on: September 19, 2014, 10:37:03 AM »
ok form what i can tel by the build
1) a higher density rockwool was used compared to the regulations (RW5 is now ProRox SL 960)
2) c-hangers are almost 12 inches lower than the original ceiling ( had very high ceiling)
3) original ceiling was 2 layers of plaster board and chalk was used around the perimeter

however the rockwool was placed on top of the joist and tightly packed so there is a void between the new joist. my main concern is if the impact vibraions are by passing the wool by going through the wall and coming in the void between the jost.

Randy S

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Re: Independent ceiling built but still hear impact noise
« Reply #7 on: September 19, 2014, 03:06:35 PM »
what percentage of noise reduction did you experience from the build? 50% ??
Randy Sieg

Super Soundproofing Co
www.soundproofing.org
888-942-7723
Ph. 760-752-3030
Fax.760-752-3040

max86

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Re: Independent ceiling built but still hear impact noise
« Reply #8 on: September 19, 2014, 05:44:56 PM »
it is hard to tell as i have become sensitive to it but i guess around 25% ish. but the impact noise is still noticable for me. However i cant hear any airborne noise though.

Randy S

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Re: Independent ceiling built but still hear impact noise
« Reply #9 on: September 19, 2014, 06:09:59 PM »
ok well getting 50% reductions on impact when addressed from the receiving end is about the best we can get, so I would suggest go ahead and add another layer of sheet rock /drywall. increase the mass.

Randy Sieg

Super Soundproofing Co
www.soundproofing.org
888-942-7723
Ph. 760-752-3030
Fax.760-752-3040

max86

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Re: Independent ceiling built but still hear impact noise
« Reply #10 on: September 22, 2014, 10:24:05 AM »
On another note, will a triple leaf effect occur now that I have a void between the joist? Therefore making the soundproofing useless or making the noise even worse.

Randy S

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Re: Independent ceiling built but still hear impact noise
« Reply #11 on: September 22, 2014, 03:11:24 PM »
did you remove the existing ceiling sheetrock or plaster before building the new ceiling?
Randy Sieg

Super Soundproofing Co
www.soundproofing.org
888-942-7723
Ph. 760-752-3030
Fax.760-752-3040

max86

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Re: Independent ceiling built but still hear impact noise
« Reply #12 on: September 23, 2014, 10:31:49 AM »
No. The original ceiling was left in place. The building regulations for my city suggested this.

Randy S

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Re: Independent ceiling built but still hear impact noise
« Reply #13 on: September 23, 2014, 04:09:58 PM »
ok then you did create the triple leaf system and you are most likely at maximum reduction. you might see a couple more points by adding more mass but that is as far as I would go unless your willing to start over.
Randy Sieg

Super Soundproofing Co
www.soundproofing.org
888-942-7723
Ph. 760-752-3030
Fax.760-752-3040