How To Soundproof A Flex Wall

Flex walls are a great temporary structure that are ideal for dividing up larger spaces within your home. The main problem with them, however, is that they’re not very good at blocking out sound.

Flex walls are often just a single sheet of drywall, which we all know isn’t the most soundproof thing in the world. However, soundproofing a flex wall really doesn’t need to be that difficult.

As with all soundproofing projects, the ease of the job will largely depend on the size and your technical ability. Below are some tips on how to soundproof a flex wall, including the best products to use.

How To Soundproof A Flex Wall

What are the Best Materials for Soundproofing a Flex Wall?

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As with almost all soundproofing projects, the key is to add more mass to the wall. Doing so will simply make it harder for sound to travel through the flex wall, thereby making it much more soundproof.

The one thing to bear in mind with soundproofing a flex wall is that it won’t be as effective as soundproofing a normal wall (read my article on soundproofing condo walls). This is mainly because flex walls often act as partitions within larger, more permanent structures, and so there simply isn’t the same kind of space available for you to work with.

That said, the best material you can use for soundproofing a flex wall is mass loaded vinyl. This is a pretty self-explanatory material, and is just very dense vinyl sheeting. The product is most often compared to lead in terms of its density and weight, but is much thinner and easier to work with.

Another option is to add more drywall, although this is best combined with something like decoupling (MY RELATED POST) to create more space for the sound waves to get “trapped” in. While they don’t literally get trapped, creating a void in the wall prevents sound waves from transferring as easily through the wall.

The major downside of this option, of course, is that it takes up valuable space, something you may not have if there’s already been a flex wall put in. Similarly, drywall isn’t necessarily very dense, so will only do so much when it comes to soundproofing.

Whichever material you decide to use for your soundproofing project, be sure to combine it with Green Glue (Amazon link).

Green Glue is a product designed specifically for soundproofing projects, and has characteristics that make it ideal for absorbing sound and preventing them from travelling through walls. You can use Green Glue for sticking things up and for filling gaps like insulation foam.

How to Soundproof a Flex Wall: Method 1

The first method suggested in this article is using mass loaded vinyl.mlv This is arguably the most effective for a flex wall, and probably the easiest method for soundproofing your space, and is slightly less invasive than installing more drywall. To soundproof your flex wall using mass loaded vinyl, follow these steps:

  1. Mark out the space you wish to cover with the mass loaded vinyl, and work out your area. This is important so you know how much vinyl to use. For best results, cover both sides of the flex wall.
  2. Once you know your area, get enough mass loaded vinyl. Because the material is so heavy, it’ll be easiest to do this in strips, as it has a weight of around 1lb per square foot, which can become difficult when you’re working with a big sheet.
  3. You can simply nail the mass loaded vinyl to the wall, but this will be most effective if nailed straight on to support joists. However, if there aren’t any joists available, nail it to the drywall but put in more nails to help deal with the material’s weight.
  4. After fixing the vinyl to the wall, stick down edges and fill in any gaps with Green Glue. If you want to go all-out on your soundproofing, apply plenty of Green Glue to the drywall before fixing the vinyl. This will give you another sound absorbing barrier.
  5. Finally, once the glue is dry and everything is fixed in place, paint over the vinyl. It’s usually black, which isn’t the most attractive room color. Either use a primer or expect to use several coats of paint to get the desired finish.
  6. Repeat on the other side of the wall if desired.

Check out this MLV on Amazon. It performs well and is reasonably priced.

Some Tips for Using Mass Loaded Vinyl

  • Although some may say otherwise, mass loaded vinyl is completely non-toxic. This makes it safe to use around children and pets and is easily one of the most effective products to use.
  • The mass loaded vinyl might smell a bit when it’s first unrolled, but this is only because of the synthetic materials. If the smell bothers you, allow it to air before putting up, and definitely before painting.
  • Mass loaded vinyl is most effective at combating airborne noise, but will also help reduce impact noise if that’s also a problem.

How to Soundproof a Flex Wall: Method 2

The second recommended method for soundproofing a flex wall is to use more drywall.


This will be slightly more technical and will involve a bit more DIY skill. Similarly, it’s a more permanent method, and will take up more space than the mass loaded vinyl. To soundproof your flex wall using more drywall, follow these steps:

  1. Start by inspecting the current drywall. Fill in any cracks or gaps with Green Glue before putting up the new wall.
  2. Next, measure out your drywall to match your flex wall’s dimensions. If necessary, cut to size.
  3. If there are any support joists in your flex wall then you have the option of decoupling the wall. This basically involves adding hangers so the individual sheets of drywall are separating from each other. However, you won’t be able to do this if the wall is only drywall.
  4. Either way, simply put up the drywall and screw it onto the existing wall. It can be helpful to spread Green Glue on the inside surface for bonding and for extra sound absorption.
  5. Finally, prepare the wall, filling any screw holes with a good quality drywall filler. Once everything is dry and prepared, you can paint it the desired color.

Tips for Using Drywall

  • Adding drywall is much more effective when combined with decoupling or sound absorbing methods. These are easier to do on walls with cavities, meaning mass loaded vinyl might be your best option.
  • However, drywall is definitely going to be the cheaper option, and the material is more readily available.
  • Similarly, if you live in a rented home, it’s a less obvious method to improve sound absorption in the space.
  • You could improve the drywall’s soundproofing ability by combining with dense insulation foam, although this will take up even more room.

Some Final Tips

Whichever method you choose for soundproofing your flex wall, remember that the project is only going to be as effective as the materials you use. For this reason, make sure you decide what will suit your needs and budget the best before starting. Also, consider these final tips:

  • Regardless of what you see online, acoustic foam and egg boxes are not even close to suitable for this kind of project. Acoustic foam is about acoustic conditioning, not soundproofing, and egg boxes are, well, egg boxes.
  • If you’re unable to do something as invasive as adding to the walls, your next best option is to add mass to the room. Heavy furniture and wall hangings will definitely help absorb noise, but not to a great extent.
  • Don’t overlook cracks and cavities. Empty spaces are prime noise transferring territory, so if you’re getting in there with the Green Glue, be sure to fill all the gaps you can see, regardless of how small they are.
  • If you can’t get hold of mass loaded vinyl, try another product that’s classed as having “limp mass”. This is basically any product that absorbs and blocks sound with little or no change to its physical structure.
  • Be aware of the power of vibrations. It’s likely that you can reduce the problem by being intelligent with electronics placement, among other things. This is assuming that the noise source belongs to you, of course.
  • Another less invasive option is soundproof curtains. Again, like the furniture suggestion, these won’t be amazing, but are worth considering if you’re unable to make structural changes.


Soundproofing a flex wall is often harder than a normal wall, as it’s not considered a permanent structure, and so doesn’t have the same kind of construction. This means that you’re limited to what you can actually do to improve its sound absorption characteristics.

However, the most important thing to remember is that adding mass is the most effective method. Something like mass loaded vinyl is designed specifically for this kind of project, but drywall will definitely help to an extent.

Whichever you choose, just make sure you’re thorough in your construction work, as the soundproofing will only be as effective as its weakest point!

Thanks for reading! Check out all my recommended products for good soundproofing.

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