Skip to Content

How Soundproof Are Duplexes?

how soundproof are duplexes

When you think you have it all laid out for a calm and quiet moment, coming right from the flat attached to yours is a terrific jam blasting from a stereo system.

It is even more disheartening after you draw the curtains, shut the windows and doors, but the jam still finds its way in as if the stereo is positioned right behind your windows.

Right there, you remember you were too much in a hurry to move into the new apartment that you forgot to check if the house was soundproofed, or you didn’t even know how to do the check.

A tip: a house that you can hear water running in its bathroom while you are at the corridor is not soundproofed.

If you also hear a hissing sound in the walls while you run the kitchen sink, it is proof that the house is not soundproofed.

There is a misconception that a duplex should be soundproofed, no doubt.

Note: This post may contain affiliate links which will take you to online retailers that sell products and services. If you click on one and buy something, I may earn from qualifying purchases. See my Affiliate Disclosure for more details.

How soundproof do you think duplexes are? 

Firstly, let’s take a look at how duplexes are structured.

What Is a Duplex?

how soundproof are duplexes houses diy methods

A duplex is a kind of house structure that has two living units attached to each other, either above each other or side by side or one behind the other.

It has two distinctly separate living units that are joined by an adjoining wall, floor, or ceiling.

Note that these separate apartments are merged together by an adjoining wall.

The adjoining wall cannot do much in shutting off the yells, slams, and footfalls coming from the other flat.

Hence, to enjoy living in your apartment, you would have to go the extra mile to soundproof it.

Methods for Soundproofing a Duplex

Soundproofing a duplex goes beyond stuffing insulation inside the wall and ceiling cavity; this does not totally shut out the sounds.

This is because the insulation is mostly air and has very little mass and density.

Sounds travel through the air, and as said earlier, insulation is mostly air, this makes it even easier for sounds to travel through insulation.

Increase wall attenuation

You might not be expecting this, but blocking sound transmission has to do with construction.

If you really want to get rid of the nerve-wracking noises from the other apartment, then you really have to do a lot more than insulating.

The reason the sounds can penetrate is that the walls or ceiling are too thin.

So, you would have to increase the attenuation of the wall assembly.

Increasing the attenuation of the wall assembly is a process that will consume 2 inches of your wall space (or even more), but this process is the only cost-effective way to block sound transmission completely.

However, if the duplex is one in which its living units are constructed above each other, the ceiling would need to be also soundproofed to reduce impact noise.

Installing two layers of drywall directly over the joists will do the job.

Asides the wall, there are other parts of the building that needs to be soundproofed if you really want to shut out sound penetrating into your apartment totally.

The door is one of those building parts.

You can improve the sound attenuation of the door by installing weather stripping materials around the sides of the door and a drop-down seal at the bottom of the door.

DIY Methods

The process mentioned above has to do with construction.

If you, however, do not buy the idea of construction, maybe because you do not have extra wall space to spare or cannot afford the cost, there are other ways to soundproof your apartment effectively.

Soundproofing blankets

Soundproofing blankets duplex insulation

The first thing you will do is to check the walls of apartments for where there are thinner walls- it is these parts that need soundproofing the most.

Then get soundproofing blankets. Amazon have some excellent ones available here.

Soundproofing blankets do a good job of muffling the noise up to 70 percent.

These blankets are very good sound mufflers made of soundproofing substances.

Installing soundproofing blankets is a DIY thing.

For more effectiveness, you can couple the blankets with a DIY soundproof wall kit, which is also easy to install.

Mass-loaded vinyl

Mass-loaded vinyl mats can also help.

Fill the thin walls with these materials, and you will be surprised at how effective they can be.

Foam mats

More like vinyl mats are foam mats. Foam mats also have high-insulating capability.

They are the best if you are not really boxed up because of how affordable they are.

They are also the ideal solution to soundproof the existing walls between apartments.

Very easy to install with the adhesive on the backside.

Sealing glue

Also, seal holes in the walls. The holes could be as a result of cable connections made in the past.

Holes, especially in thin walls, transfer sounds.

After locating the holes, get a good glue to seal them.

One of the best sealing glues sold in the market is the Green glue.

This glue will perfectly seal the holes and shut out the noise.

Acoustic foam

Another soundproofing material you can try out without having to construct is acoustic foam.

This material can block a loud noise, up to 70 percent.

You will even get a better result if you combine this material with other methods of soundproofing.

Fill out spaces

Sounds penetrating into your apartment might be as a result of empty spaces.

If you have empty spaces in your own unit of the duplex, there is every possibility that every sound would end up penetrating the walls of your apartment and bouncing around.

So, fill out spaces by placing furniture like bookshelves, closets, etc. in your apartment.

Although this might not give you the best result, it certainly would reduce the noise to some extent.


Duplexes are not all soundproofed until you take extra measures of soundproofing them either by constructing additional layers for the walls or filling the walls with soundproofing materials.

You Might Also Like: