Author Topic: Soundproofing common party wall, sanity check  (Read 3039 times)


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Soundproofing common party wall, sanity check
« on: January 08, 2015, 07:14:40 PM »
Hi all,

First post here. I could really use some help to see if I'm on a right track here or not.

Some background:
We live in a 110 year old brick 2 story row house. It's ultimately a brick duplex with a flimsy partition/party wall. Party wall is plaster with single row of loose brick in between. Neighbor is not too noisy but party wall is not soundproofed so I'd like to improve that. I'm targeting master bedroom only as that's where we hear our neighbor the most. When I say hear I mean hear foot steps, music, and most annoyingly - conversations, where we can sometimes make out individual words. Oddly enough, we can also hear him talk and close kitchen cabinets on the 1st floor while in our 2nd story bedroom. So, the goal is to muff the noise to a point where it doesn't bother us much.

Our house's been renovated some by the previous mostly DIY owner. Unfortunately, little to no attention had been given to soundproofing. Neighbor's house's been flipped about 7 years ago so I'm pretty sure he's got no original plaster left. We still do have all of our perimeter plaster walls intact, and original hardwood floors, with no subfloors btw.

Our 2nd story master bedroom is at the end of the house. Party wall our side stills has plaster there. There is a single electrical outlet in the middle of the party wall. Previous owner had raised the ceiling height by exposing half of 2x6 (measured really 2x6) 24" on-center ceiling joists. Exposed joists are out by 3.5". We have what looks like a sheet of 1/2 drywall between individual joists. There is a ceiling fan installed as well. Roof slope is really low something like 2x12, slopping towards our master bedroom. Old metal roof is covered with rubber layer. Oh, and there is no firewall between 2 houses in the attic. Attic is inaccessible around the maser bedroom.

My suspicions/findings:
1. We have tons of noise flanking from all sides, ceiling with exposed joists, under the floor, and through the wall itself, in that order I suspect.
2. We have shared floor joists and no subfloor hence lots of impact noise, and 1st floor noise infiltration.
3. We have no firewall to block any sound in the attic.
4. Secondary but I suspect exposed ceiling joists, low roof pitch with blown insulation(?), and N/NW facing corner master bedroom is that what makes for a noticeably colder/warmer room, depending on the season.

Things I'm considering:
1. Start addressing or improving 1 problem/project at a time, starting with ceiling first, then floor and then party wall.

2. Remove ceiling drywall and build a small attic firewall, use acoustic caulk, add insulation bats and close it in with fire rated drywall (on one side only as I have no access to the other side).

3. If my wife lets go of exposed ceiling joists in the bedroom then, install roof baffles if needed, put either R-19 or R-30 insulation between 2x6 ceiling joists, add resilient clips/channels and install 2x 5/8 or 2x 1/2 sheets of drywall with green glue in between. Apply acoustic caulk around. We'd loose 6" of ceiling height that way vs exposed ceiling joists down to 7'3" ceiling height. I'm also concerned whether ceiling can support 2 sheets of drywall or if I should do 1 instead.

4. If wify says 'keep' on exposed ceiling joists, I was thinking about installing MLV on the part of the joists facing the attic, basically wrapping them with it. My side concern is extra weight 1/2 pound per sq/ft MLV is gonna add to 2x6 24" on center joists. I could then added 2 sheets of 5/8 drywall between joists but I suspect it'll be a waste of effort. So, 1 sheet of 5/8 drywall then.

How does that sound? Am I missing anything? Am I on a fools errand here guys? Thanks for reading this far. :)

Randy S

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Re: Soundproofing common party wall, sanity check
« Reply #1 on: February 02, 2015, 04:55:24 PM »
Ok the best way to answer all your questions it would best to contact me directly so I can explain the best course of action.
This will allow you to address all your problems as you go forward with the projects.

I look forward to discussing this with you.

Best Regards,

Randy S.


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Re: Soundproofing common party wall, sanity check
« Reply #2 on: July 31, 2015, 03:50:51 PM »
Randy, thanks for your reply. It had scrolled off my radar. Sorry about that. Project got delayed to a point where it was too late to start it. So I pushed it back to next cold season. Looks like some time in January is the new start date.