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Multifamily or Duplex : How to make the dividing wall quiet on a budget?

JonN

Posts: 4

October 30, 2024 - 8:17 pm

I bought a duplex and I’d like to do my best to make sure I don’t hear my neighbors (much). This doesn’t need to be recording studio quality. I just don’t want to be bothered by neighbors, and I don’t them to be bothered by me when I watch a movie at 10pm. I’m remodeling and we have to build a 2×4 stud wall in front of the wall that divides the two sides. So I am going to try to “sound proof” it against movie nights while keeping costs manageable.

I can do the double wall, air gap and rock-wool method (cost $4 a square foot) and have money to spare. I’m not sure I can afford the 4″ sandwich of MLV and MDF (cost $26 per square foot). Is there something in-between?

Lots of details in the next post.

JonN

Posts: 4

October 30, 2024 - 8:18 pm

Lots of details below:

Primary Structure:
===============================

The center wall is 4″ structural clay tile with plaster on both sides.

The dividing wall is very similar to what is pictured here:

https://upload.wikimedia.org/w…..e_cost.jpg

This is all what separates the two sides. The main living rooms all share this dividing wall.

Previous Plan: $3.95 a square foot
===============================

I was going to do the following system which is well within my budget.

Dividing wall Treatment:

* Structural Clay tile
* 1″ Micro-air by John’s Manvile (similar to Corning 703 but significantly cheaper)
* 1-2″ air gap
* 2×4 stud filled with Rockwool Safe and Sound
* Two layers of 5/8 Type X drywall

Living room shelves, cabinets and a faux fireplace will be mounted to this secondary wall so I’m not sure resilient channel is a good idea.

Ceiling Treatment:
* 10″ joists filled with Owens Corning R-30 Kraft-faced insulation batts
* 2 layers of drywall 6″ from dividing wall.. set between joists

Floor treatment:
* Sand filled Cinder blocks in crawl space 9″ from dividing wall that sits on cinder blocks.
* 10″ joists filled with Owens Corning R-30 Kraft-faced insulation batts

Current Plan ???
===============================
After seeing your videos I’ve considering going an alternative approach. I love the idea of your MDF and MVL sandwich, but that would cost me $25.34 per square foot of wall. Labor costs would likely be significantly higher. And I’m guessing this is just the start.

Is there a budget version of this?

Dennis Foley

Posts: 645

October 31, 2024 - 9:22 am

You must build a barrier that can manage full range noise. This cannot be managed in 4″. You can mitigate middle and high frequencies at 4″ but no low frequency management at this depth no matter what materials are used.

JonN

Posts: 4

October 31, 2024 - 9:42 pm

What do you recommend? My original plan was almost 11″ thick:

* 4″ structural clay tile + 1″ fiberglass +1″ air gap + 3.5″ studs and rockwool + 2 layers 5/8 drywall (1 1/4 total)

totals out to 10.75″ wall

I’m ok with 11″.

Your advice is welcome.

JonN

Posts: 4

November 3, 2024 - 7:44 pm

So what do you recommend?

Dennis Foley

Posts: 645

November 4, 2024 - 5:09 pm

All noise must be measured over a 7 day time period to determine maximums and minimums in pressures. We have processes to assist you with this process. Send us contact info to info@acousticfields.com