We love cars of all shapes and sizes, and we never autobody-shame our fellow car enthusiasts. Real vehicles have curves, and we’ll be the first to admit we like a little "junk" in our car trunks. Unfortunately, that "junk" can cause unwanted noise.

If you have a subwoofer, you need trunk sound deadening to stop vibrations and rattles, and quiet exhaust noise and tire noise from leaking into your cabin and ruining your music.

Luckily, the trunk is one of the easier spaces to apply sound deadening and sound blocking material, and we know just how to soundproof trunk rattle from subs.

Absolutely, it's one of the loudest parts of your vehicle! Trunks are essentially echo chambers made of big, flat quarter panels, a big sheet of metal as the trunk floor pan and covering the wheel wells, and a light, hollow, trunk lid that's probably not firmly attached (worse in hatchbacks). Your trunk also houses your spare tire, a jack, roadside kits, tools, groceries, golf clubs, your gym bag, and whatever else you need to haul from A to B. With little to no insulation or sound deadening, all that adds up to is lots of noise.

Install a killer subwoofer and you've got extra vibrations and structural noise being generated that your rear deck and trunk area just aren't built to handle (especially not the trunk lid). Your sub is supposed to upgrade your car audio, but instead this degrades the listening experience.

By sound deadening your trunk, you can put a stop to those vibrations, and when you pair that sound deadening with a sound barrier, you can stop road noise from leaking into your trunk and ultimately your cabin.

Soundproofing your trunk will give your aftermarket audio system the chance to sparkle like it should, and it allows you to enjoy your music free from road noise and exhaust noise seeping in from the back of the car. For a quiet trunk you have to stop the noise from coming in AND stop your trunk from creating noise. We offer trunk insulation kits to make this as easy as possible. Each kit enables you to create two layers - the sound deadening layer, and the sound blocking layer. But before you add, you must take away.

STEPs to soundproof A Trunk

Here are the three steps to take you from worst to first in the trunk soundproofing world:

1. 1.  Prepare your trunk by removing everything and cleaning all the metal
   2.  Deaden the metal with Damplifier Pro™ sound deadener
   3.  Block noise with Luxury Liner Pro™ mass loaded vinyl

Want to watch a pro? Check out this trunk project with Mark from CarAudioFabrication!

Before you get started, remove absolutely everything from your trunk and rear deck to get all the way down to the metal panels. This means taking out the spare tire, carpets, and trunk card (cardboard or carpet that covers the entire trunk floor pan). If you run into wiring, do your best to safely tuck it into enclosures to keep it out of the way. If that doesn’t seem possible, decide whether you need to temporarily remove the wiring or if you would be able to work around it.

Carefully strip the walls of your trunk to expose the interior quarter panel and your trunk lid, and thoroughly clean the sheet metal and the lid with denatured alcohol.

With a subwoofer installed, cover 100% of the trunk, walls, rear deck, and lid with sound deadener. Focus coverage on the wheel wells and the lid as those are the source of a lot of vibration. Deadening the trunk lid is especially important due to the vibrations bouncing and clashing with the closure as you drive along the highway. You may also want to use a decoupling foam, like OverKill Pro™, to prevent the rear deck lid from rattling or bumping your back window. This is because your trunk is subject to much stronger vibrations than it would face from normal rattling and road noise.

You may be surprised to learn that most trunks are between 15 and 30 square feet. Ensure you have the right amount of high quality sound deadening material. Trunks are full of nooks and crannies so when dealing with tricky areas we recommend using a sharp utility knife to cut your deadening material down to smaller squares to make it easier to apply. Sound deadener is most effective if it’s fully adhered to your trunk, so apply firmly using a hand roller.

INSTALLATION TIPS

If you decide not to cover 100% of the metal surface, put the bulk of the trunk sound deadener on the flatter, flimsier metal sheets. The curved parts of the trunk are more structurally sound and tend to rattle less. If you're trying to conserve sound damping material, use the checkerboard approach highlighted in Mark from CarAudioFabrication's video build.

Imagine unwanted noise like a thunderstorm. While sound deadening material only needs to go on some of the structure to keep your house from rattling, the only way to stay dry is to be fully covered from the rain. If you want to keep noise from raining on your parade, apply automotive mass loaded vinyl to the entire floor and walls of your trunk. There are 2 approaches to this.

One of the easier methods is to adhere our Luxury Liner Pro™ to the cardboard shelf or carpet that covers your spare tire, which allows you to remove the material as needed. As long as the trunk is fully covered and the foam side faces down, you will get superior sound blocking.

If you want to be thorough, the best way to keep out road noise is to apply sound blocking material directly over your sound deadening material. Head over to our Luxury Liner Pro™ page to use our coverage calculator tool to determine exactly how much material you'll need. It’s super important that you get FULL coverage and use foil tape to seal any gaps. External noise will leak through any opening it can find.

INSTALLATION TIPS

Note that most cars have a ‘relief vent’ in the trunk. This is a flap that equalizes the pressure when you close your trunk. DO NOT cover the vent! If you do, you may not be able to close your trunk anymore (physics is crazy).

Be sure to check that your spare tire and other parts will fit back in their place with the addition of the 100% coverage sound blocking layer. To easily access the spare tire, either don't use an adhesive or cut the Luxury Liner Pro™ to fit exactly over the spare tire enclosure.

Check out our trunk kits to get all the sound dampening material you need plus a hand roller and quality adhesive to fully soundproof your trunk space.

Our products are made of high-quality, fire-resistant materials with safety in mind. Our mats are 100% high quality butyl (no asphalt!) and are proudly manufactured in the USA.

• Damplifier Pro™ should be installed on at least 60% of the trunk's metal. Focus on the larger, flatter metal spaces. Placing sheets in a checkerboard pattern will help you get the most out of the material.
• Don't forget the lid and the wheel wells! These are two of the noisiest parts of any vehicle.
• Install Luxury Liner Pro™ on top of the sound deadening. Don't forget to leave access to the spare tire!