Author Topic: This Old House has large party wall  (Read 2936 times)


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This Old House has large party wall
« on: October 30, 2014, 03:20:45 PM »
I am currently renovating a large older (100 Yr) home that is basically a side by side duplex with 2 floors in each unit.  There is a party wall between the units which is approxmately 720 square feet.  Most of it (2 thirds) is on a stair well through the middle of the house.  There is a common 4 foot crawl space that is not partitioned, and a low common roof that has perhaps a 4-5 foot peak.   I have no access to the roof without taking out the ceiling.  There is also a common porch in the front which has separate entrances.  Right now, they use hollow interior doors to access each unit.  Safety not a real issue here :) , but thinking solid doors would help with sound.

The party wall is constructed as follows.  Outside layer is 1/8 hardboard over a 1/4 fiber board (called 10 test in Canada). Then there is 3/4 inch T&G strapped to the common wall stud, which is about 6 inches thick.  Then the opposite wall.  The cavity is hollow.  The outer hardboard layer is not taped, as seen in pics.  They have merely trimmed over the joins.

I plan to put down pine plank floors throughout the house, so I am wondering if anything can be done with the sub floor before I do.

I guess my next question is how effective is what I already have in place?  Anyway I can test the wall to see what noise levels are now? Bit tricky to do in a vacant house.  Should that make a difference?  I would assume it does.

The task of taking down one side of this wall, is  a bit overwhelming, certainly if my gain in attempting to sound proof the units is going to be negligible.  With most of the wall being on a stairwell, I am also restricted with how much I can build out with MLV, for example.

How much gain will I get from tearing down the wall, installing soundproofing insulation, sealing open cavities, and re-applying sheet rock layers?  Keeping in mind my crawl space is open.  I am concerned how much sound will still come around any measures I put in place?

Would appreciate some advice on how I might proceed.  I am not about to spend a small fortune on this (it will be a rental), but if I thought I could get some significant gains with not too great an outlay of cash, then I'd consider doing it.  Right now, the noise between units is bearable if potentially annoying for a shared home.


Randy S

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Re: This Old House has large party wall
« Reply #1 on: November 04, 2014, 06:18:03 PM »

It is definitely worth opening up the walls to insulate for noise control and while you have it open you can do the detail work of sealing the wall correctly.
Give me a call direct and lets discuss this project in detail so you can make the decisions I make in sound control projects.

Randy S.