How to Soundproof a Door
How can you stop—or at least reduce— noise coming from outside a room? Fortunately, there are a few easy ways to soundproof an interior door, and we’ll tell you how.
There are lots of times when you just want a little peace and quiet. All you need to do is find a room and shut the door, right? But if you’re in a noisy household, chances are that some of the sound will follow you into the room.
How did it get in? Probably the same way that you did, through the door. How can you stop, or at least reduce, the noise? You can wear noise-canceling headphones, sure, but then you might not hear what you want to hear. Soundproofing a door can be accomplished by a low-tech hack or a fairly involved procedure and can be inexpensive or pricey, with a range of options in between.
How Does Sound Travel Through a Door?
Sound is an energy that travels through a medium (air, water, glass, wood, etc.) by vibration. The particles in a medium nearest the source bang into the adjacent particles, which bang into the next ones, and pretty soon you have a vibration that creates sound.
The greater the density of the particles, the less the sound can move. It makes sense, then, that sound travels more easily through the air, rather than through a brick wall. In an enclosed room, the less dense perimeter areas are typically the windows and especially the doors, mainly because they have air gaps.
DIY Ways to Soundproof a Door
Method 1: Seal the gaps
Most interior doors, unlike those on the exterior, are not weatherstripped. There’s always a gap below the door and one that runs up the sides and over the top. By sealing these gaps, you will diminish the sound coming through.
An easy and inexpensive method is to buy adhesive-backed, flexible foam weatherstripping. It’s available in various thicknesses and widths.
Tools and materials needed:
Screwdriver (manual or cordless)HacksawAdhesive-backed, flexible foam weatherstripping
Aluminum and vinyl door sweep (that’s at least as long as your door is wide)Steps:
Removing the backing as you go, apply the foam strip to the edge of the doorstop (the trim onto which the door closes); you can also apply the strip to the outer perimeter of the door that closes onto the jamb.If the foam prevents the door from closing, try a thinner variety. You may also have to adjust the strike plate on the door jamb so that the door closes properly. Next, add a door sweep to the bottom of the door. Again, there are different varieties of sweeps, but the easiest to install are those that are applied to the surface of the door that faces the room’s interior. They consist of a neoprene or vinyl flap that’s held in place by an aluminum channel. To install the door sweep, close the door, place the sweep onto the floor, mark and cut the sweep to match the width of the door. Screw the channel to the door. If your floors are uneven, you may have to adjust the height of the sweep. Alternatively, there are ready-to-install kits made to reduce sound transmission that consists of neoprene seals mounted onto aluminum tracks. Prices start around $250 for a standard kit.
Here’s another alternative to weatherstripping that’s in keeping with the original look of the door: if there’s a large gap under the door, you could add a thicker threshold. You’ll still have a gap, but it will be smaller and so will allow in less sound. You’ll have to remove the existing threshold with a flatbar. If you’re careful to remove it one piece, you can use the original as a template for the new threshold.
Gaps in the trim that’s applied to the door jamb can let sound in too, although probably to a lesser extent. To do a thorough soundproofing job, run a bead of caulk wherever there’s a gap.
Method 2: Increase the mass of the door
Sound can penetrate solid objects. The greater the mass of the object, the less the sound will penetrate. If the door has a hollow core, you could replace it with a solid door—that is, if you want to make that investment. On the cheaper end of the cost spectrum, you can increase the mass of the door by hanging a thick blanket or carpet on it—an easy but temporary fix.
Tools and materials needed:
Utility knifeStraight edge Caulk gun Construction adhesiveScrews
Screwdriver Roll of mass-loaded vinylIf you’re not picky about the appearance of the door, you could screw a similarly-sized piece of plywood to it; just be sure to leave enough of a gap around the door so that the plywood doesn’t interfere with the door’s operation
If you really want to get serious without replacing the door, you can get sound-reduction mats made especially to be hung on doors. These are the most effective at slowing the transmission of sound waves, but they don’t come cheap. A sound barrier custom made for your door is one option.
A slightly less expensive option is to make your own barrier from a material called mass-loaded vinyl. Resembling a rubbery sheet of lead, it’s available in different thicknesses; the thicker (and heavier) the material, the greater the sound reduction. It’s only available in rolls, so if you’re only soundproofing one door, you’ll have plenty of leftovers.
Carefully measure the door, then roll out the vinyl and transfer the measurements onto the material. Use a utility knife and a straightedge to ensure that the cuts are straight. Check the fit—you may need a helper here, it’s heavy stuff. If you’re covering the side of the door that closes onto the jamb, make pencil marks that indicate where the vinyl should be placed to avoid interfering with the door’s closing. Remove the hinge pins from the door hinges or unscrew the hinges from the jamb, remove the door from the jamb, and lay it flat on the floor. Use a caulk gun to run a bead of construction adhesive around the perimeter of the door and on any surface that the vinyl will contact. Place the vinyl onto the door, make sure it’s bedded in the adhesive, allow the adhesive to dry and re-hang the door.
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