9 Steps to Easily Soundproof a Cardboard Box

A microphone in a soundproof box

Last updated: April 10, 2021 at 17:40 pm

Learning how to soundproof a cardboard box might seem a strange idea. However, it has a number of great uses including voice/audio recording and generator soundproofing.

In this article:

We’ll explain exactly what you’ll need to soundproof a box, and 9 easy to follow steps to do it properly.

What You’ll Need

To complete this job properly, you’ll need the right materials:

Cardboard Box

Remember, it will get smaller once you add the soundproofing, so make sure the one you choose will still fit once you’re done. If you already have plenty of cardboard, there are lots of online tutorials showing you how to build a box yourself. The benefit of this is you can make it the perfect size for your project. Otherwise, they’re easy to buy. You may even be able to get one free from the local supermarket. Either ask a member of staff or check around their waste areas. You might also check your loft. Most people put the boxes up there from appliances they’ve bought in the past. If you’ve since replaced that appliance, then you have no other use for its box.

Acoustic Panels/Polystyrene Sheets

This will work with the soundproofing material to add mass and block sound. It’s also makes for a secure surface to glue the soundproofing onto.

Soundproofing Material

Mass loaded vinyl is an excellent choice as it’s thin and flexible, making it easy to install.

Adhesive

This can either be standard bottled glue or spray-on adhesive. Spray-on may be easier to use, but it depends on what you’re comfortable with and what you already have on hand.

Measuring Device

A tape measure or ruler is fine; use whichever you already have. A ruler can also be used as a straight edge for cutting the polystyrene panels.

Scissors or a Craft Knife

Make sure they’re sharp for precise cuts. To get the maximum effect, you need to have no gaps.

Marker

You’ll need it to create references for your cuts.

How To Soundproof a Box in 9 Steps

  1. Measure the interior of the box. You’re going to need exact measurements, so do this carefully and remember the old adage – measure twice, cut once. Make sure it will still fit the intended item inside once you lose an inch or so on all sides. If you’re planning to use the box as permanent soundproofing for a generator or pump, make sure the box leaves space enough around for heat to escape. If it’s too tight, it could represent a fire hazard
  2. Mark up the polystyrene sheets to create two panels per side of your box. This works out as twelve if you’re covering the entire box or ten if you’re leaving the top open. Depending on the size of the box and how much noise you’re trying to block, it may be worth using a double layer, in which case you’ll need 20-24 squares. Remember that the bottom panels will cover all the way to the edge, so you’ll need to take this into account when marking the side panels.
  3. Cut the panels out carefully using scissors or your craft knife. Keep it as straight as possible; you want as small a gap as possible between the sheets.
  4. Apply the adhesive. It’s better to apply it to the box and give it a few seconds before pressing on the polystyrene. Normal PVA glue should be fine, but there are special polystyrene adhesives if you prefer to use them. Make sure all surfaces of the box are fully covered and that the polystyrene is firmly attached.
  5. Tape up the joins. We don’t want any gaps to let sound escape. The usual recommendation is to use acoustic tape, but this may be unnecessarily expensive unless you have some from another project. Thick masking or packing tape will do the trick.
  6. Apply the soundproofing material. Options you can use include mass loaded vinyl, acoustic foam and a product called Dynamat, which space is often used to soundproof cars. It’s easy to source and not particularly expensive. Whichever material you choose, measure precisely and be careful cutting it. Make sure you use plenty of glue and that the soundproofing is secure.
  7. Tape up the joins between the pieces of soundproofing.
  8. Cut out any necessary holes. This might be to put a power cable through if you’re using your box for a noisy appliance. If you’re using it for a generator or pump, then please remember these devices generate a lot of heat. You need to add a couple of holes or slits for ventilation to ensure it doesn’t overheat and break down.
  9. Place the box over your boiler or pump, or slide your amp or blender inside and make sure it fits properly. If you’re placing your item into the box, consider if you need to add a strap to hold it in place.

Soundproofing the Box (FAQ’s)

My box is too small. Can I soundproof the outside instead?

Yes, you could. It’s exactly the same process as described above. Obviously, it’s not going to look too great. This isn’t a problem if it’s tucked away in your boiler cupboard or garage, but if it’s going to be hanging around your kitchen, you may want to add a layer of coloured paper to the outside when you’re done.

Does it matter what soundproofing material I use?

No. Any of the options listed above will work. What you choose depends on their availability and your budget. Do a little research and pick the one that best suits your needs.

What if I can still hear the noise?

It’s unlikely you’ll be able to block 100% of the sound, but if it’s still too much for you, you could add another layer of polystyrene. If there’s room, you can add it to the inside. If not, you could add another layer on the outside. It won’t look pretty, but coloured paper or sticky back plastic could both smarten it up.

Could I use bubble wrap as my soundproofing material?

No. Bubble wrap is designed to protect items from being broken, not to block sound. Firstly, it isn’t thick enough to add much mass, and mass is what you need to stop sound. Secondly, the mass it does offer will decrease as the bubbles pop, meaning you’d have to keep replacing it.

What about egg cartons?

Like bubble wrap, egg cartons stop things from breaking; they do not block sound. Your box is already made of cardboard, so adding another layer will do almost nothing to improve its soundproofing properties. It’s an old wives tale that you should use them for any type of soundproofing project; it doesn’t work.

Why Soundproof a Cardboard Box?

If your water pump, generator, or boiler is noisy and it’s affecting the peace in your home, then enclosing it in a soundproof box can be an inexpensive solution. Be aware that if it’s suddenly making noise when it didn’t before, there may be a fault. Check this out first with a qualified professional, and if all is well, proceed with the soundproofing.

If there’s a new baby in your home and you want to prep meals at night using noisy devices like a blender, then putting a soundproof box over them while they’re in use is much easier and cheaper than soundproofing the baby’s room. If you find a big enough box, this might work for a noisy washing machine too. It’s probably easier to use MDF for that, though.

Are you a musician? Enclosing your amp or microphone in a soundproof box means you’ll get a purer sound when recording yourself by filtering out ambient noise.

Conclusion

As soundproof projects go, this is one of the simplest ones to attempt yourself. It’s so simple it’s often set as a science project in schools. The benefits are that it’s not very expensive compared to soundproofing whole rooms to block out the sound that’s bothering you. It’s also temporary, so if you do need to use it in your kitchen or another small space, you can easily put it away when it’s not in use.

A cube is one of the easiest shapes to work with, so if it will be on permanent display, you can make it look decorative using coloured paper, wrapping paper or sticky back plastic, which comes in a range of designs. Finally, it should be very effective as long as you’ve followed the instructions carefully. Just remember to check your measurements at least twice so you don’t make a mistake and waste materials. Good luck with your project!

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About the Author: AJ

Hi, my name's AJ! I write about living a quieter life, soundproofing tips and recommending the best quiet products here on Quiet Living.

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