Soundproofing between floors of a duplex

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Posted by: from Verdun
3/29/2012 at 3:20:12 PM

My tenants are constantly complaining of sound travel from upstairs to downstairs and vice versa. What is the best way to soundproof a duplex/triplex which was built before 1950 in montreal?

I don't want to lose more than a few inches in ceiling height. I have heard that opening up the ceiling for blown insulation will do nothing because the problem is not the insulation, it's the fact that the floor joists of the second floor and the ceiling of the 1st floor are too closely connected and the sound travels through the joists.

Would it be the best to glue a layer of rigid foam insulation to the existing ceiling and then screw 1 x 2s to the joists above, and then drywall as normal? This would take up 1.5 inches for the rigid foam, 3/4 for the 1 x 2's and 5/8 for the new drywall. Would that make a big enough difference? This is a common problem here so any advice for the best method would be appreciated.



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Date/Time3/29/2012 at 4:25:54 PM

Hello James,

The best option is to create a false ceiling if you have enough space. insulate the existing floor create a 2" air space between the existing floor and the new false ceiling. insulate the new false ceiling, install resilient channels then a layer of 1/2 drywall, a layer of 5/8 plywood and then another layer of 5/8 drywall.

Make sure non of the joints line up. We use this method for sound studios it's very elaborate but it works!

Another option would be to install sound proof insulation in the existing floor install resilient channels then at minimum 2 layers of drywall if you can get the layer of plywood in there it would help. An air space between the existing floor and the drywall is important to help baffle the noise.

If you have any other questions please do not hesitate to ask.



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James in Verdun
Date/Time3/29/2012 at 4:35:58 PM

Thanks Mike,

That sounds thorough. I have no idea what you mean by "resilient channels" in your descriptions however. would I be right in assuming it would be like installing 2x2's across the existing ceiling for your resilient channels and then insulating that new false ceiling?

And when you say to make sure none of the joints coincide, does that mean that you recommend putting the resilient channels perpendicular to the existing joists so as to minimize vibration transfers that would occur if they were parallel?



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Date/Time3/29/2012 at 6:05:43 PM

Resilient channel is also called Z bars. They are metal tracks and install perpendicular to the joists and they help isolate the drywall from the joists. If you install 2x2's you really don't get much benefit. Batt sound insulation will help.

Another option is to suspend steel channels on wires ( like a dropped ceiling ) and attach the drywall to the channels. They also make sound deading drywal, it works well but is expensive, about $75 a sheet.

Staggering the joints, means to offset the layers of drywall so that the seams don't land on top of each other.

Another source of noise is hardwood and laminate floors, carpet or area rugs are better. The heating ducts also transmit a lot of noise, but is much harder to deal with.

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Date/Time3/29/2012 at 8:45:11 PM

Hi James,

I agree with James regarding the 2x2's they will only transfer the sound. Resilient channels is a metal furring strip. it would act like a 2x2 but it wont tranfer the noise. James answered the other questions you had reguarding the laping of the sheets when they are installed.

And yes carpet will also help to reduce noise.

Good luck with your project.


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Date/Time4/1/2012 at 3:29:01 PM

In addition to the resilient channels, you can also use a special drywall that has termendous sound dampening characteristics.


Kingsway Construction Inc

Glenn Rosborough

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