The International Residential Code (IRC) defines a party wall as a wall between two separate homes that must have a 2-hour fire rating.

Party walls are also simply known as shared walls or common walls. They divide two residences or businesses owned by two separate people. Despite what the name may indicate, a party wall isn’t really designed for soundproofing the booming speaker system of a Saturday night rager. Sometimes the local regulations are much more focused on the fire rating, and the wall has terrible soundproofing.

When your party wall is not soundproofed, it can be extremely frustrating. And based on the people who call in to talk to our soundproofing specialists, the neighbor is most likely a disaster. We’ll go ahead and say it now – staying on good terms with your neighbor can make solving a soundproofing issue MUCH easier. You may even be able to get them to invest in the project along with you!

The types of issues we hear the most through a party wall are people talking, wall-mounted TVs, and stereo systems. The party wall is typically between two condo owners or a duplex – and all of these sound issues are fixable. Depending on the type of noise being heard, we may need to address a structural noise issue or an airborne noise issue. The solutions are different, but some proper soundproofing will mitigate either one.

Structural Noise in a party wall construction

Structural noise is more likely to be an issue with a wall mounted TV or speaker. The vibrations are transmitted through the structure of the building from one space to an other. You can reduce structural noise by isolating the source of the noise from the building’s structure. We will use a specialized sound isolation clip to decouple the TV or speaker from the wall. If the vibrating speaker or subwoofer is on the floor, then decoupling that speaker from the floor with 100% rubber is an effective treatment. You will be able to feel the difference after isolating the noise source by touching the surrounding space with your hand.

Airborne Noise

Airborne noise (people talking, the TV) is the most common noise issue when soundproofing a party wall. Airborne noise is transmitted through the air and can be reduced by ensuring the noise barrier is sealed up tight and then adding additional density to that barrier. You have several options to soundproof a party wall for airborne noise.

The best way to soundproof a party wall is by adding density to the walls and decoupling them from the framing structure, if that is possible. The approach for party wall soundproofing on a new wall and an existing wall is a little different.

Soundproofing common walls can get complicated if the relationship between the tenants has devolved or if there’s a restrictive party wall agreement. The first thing to consider is whose responsibility is it to soundproof the wall! If you’re in an apartment, you will need the landlord’s permission to make structural changes to the wall. The only thing you can do without the landlord's permission is to cover 100% of the wall with BlocknZorbe. Screw the panels into the wall and then remove them when you leave.

Assuming this party wall is in a condo or business where you can make structural alterations, you have more wall soundproofing options. The solution depends on if you want to tear down to the studs or if you want to soundproof an existing wall in your home.

Soundproofing An Existing Party Wall

If you don’t want to tear down the existing wall, we have good news and bad news. Bad news first you say? Well, the bad news is that you only have one option. The good news though is that that option is a really good one.

What you’ll need is acoustical caulk, Green Glue, and 5/8” thick drywall. For any soundproofing project, always go with 5/8” drywall or soundproof drywall.

The first step is to seal up the existing wall with the acoustical caulk. Acoustical caulk is your best friend in a soundproofing project, because you’ll see large gains just be sealing gaps around the perimeter of the wall and any penetrations, like outlets and vents. Next, add a new layer of 5/8” drywall with Green Glue between the two layers of drywall. Then seal everything up with acoustical sealant again.

Soundproofing A new Party Wall

If you are working from the framing, you have more options for a soundproof party wall. You can use mass loaded vinyl, Green Glue, RSIC clips, or a combination of all 3! We go into more detail in our wall soundproofing article, but the basic steps for an example high performing new wall are below:

1. Fill stud cavities with insulation. If you’re going to be using specialty soundproofing materials, any insulation will do. For more on that read our article on does soundproof insulation work?
2. Install RSIC clips to the studs. Snap in 25 gauge hat channel to the isolation clips.
3. Screw the 5/8” thick drywall into the hat channel. Seal around the perimeter and any penetrations with acoustical sealant. You could stop here and have a perfectly awesome soundproof wall. Or you continue the party… wall construction to continue increasing the STC rating.
4. For additional soundproofing power, add an additional layer of 5/8 thick drywall with Green Glue on top of the existing assembly. Then seal around the perimeter and any penetrations all over again.

For any soundproofing project, Second Skin has you covered. Whether you’re soundproofing a party wall, a recording or podcast studio, a home office, a bedroom, a commercial office, a restaurant, a warehouse… we could keep listing, but I think you get it. We have all the tools, tips, and techniques you’ll need to do a soundproofing project right the first time.