The Washington PostDemocracy Dies in Darkness

How to soundproof walls in a townhouse

(iStock)
Placeholder while article actions load

Q: I live in a townhouse where my neighbor’s unit and mine share a bedroom wall. I can hear them snoring, and I assume that, because it’s an interior wall, there is no insulation. What are my options for solving this problem?

Baltimore

A: A shared wall is often called a “party wall,” but it’s no party when a neighbor’s snoring keeps you awake. Sound transmission through shared walls is a common problem, so it’s no surprise that there are many products available to help. These include sound-blocking rubberized paints, special kinds of drywall and thick membranes designed to be installed under a new layer of drywall. Insulation can help but generally isn’t enough. “Decoupling” your wall, so it isn’t attached to your neighbor’s wall, or adding mass (or both), will help more.

About 10 years ago, another reader wrote in with a question similar to yours, except the issue was hearing the neighbors sneeze. At that time, Gary Ehrlich of Hush Acoustics, a consulting firm in Fairfax (703-534-2790; hushacoustics.com), recommended removing the drywall on the reader’s side, building a second wall about ½ inch away, adding batt insulation and covering the studs with two layers of ⅝-inch drywall. Removing the existing drywall would increase the depth of the air gap between the units, and adding two layers of thick drywall would boost the mass, he said.

About a decade later, are better solutions available? Better, in the sense that some will save floor space, said Ehrlich, who still operates his business but no longer consults on small residential projects.

The most cost-effective solution is still to add a second wall about ½ inch from the existing one, he said. But he noted that people hate losing floor space. If that’s an issue, he suggests modifying his earlier advice, so only a 3½-inch-wide strip is taken out: Still build the new wall ½ inch from the existing one, but use metal studs 2½ inches deep, an inch less than so-called two-by-four wood studs. And instead of using two layers of ⅝-inch drywall, install a single layer of ½-inch drywall, which would provide better sound blocking than you have now.

Add a bead of acoustical sealant, which is formulated to stay flexible and not shrink, to close the gap between the bottom edge of the drywall and the floor. If there are any other places where the new drywall doesn’t meet up with the existing drywall, use the sealant there, too. (A 28-ounce tube of Titebond acoustical smoke and sound sealant is $9.99 from Ace Hardware.) Close the drywall-to-drywall joints with joint compound and drywall tape, just as you would in any drywall installation.

If saving space matters more than saving money, Ehrlich recommends exploring some of the options that have proliferated in recent years. Instead of building a separate wall, you could remove the existing drywall on your side, add resilient sound-isolation clips and attach channels to hold the new drywall to those. This would decouple your side of the wall from the other. You’d lose a strip of the room just 1⅝ inches wide, saving just under two inches. But that savings would come at a price: A box of 50 clips costs $240 at Acoustical Solutions.

Or you could remove the existing drywall and skip the clips, then install drywall with a sound-dampening layer in the middle — a solution that wouldn’t need to cut down on the room size. QuietRock makes 4-by-8-foot sheets that are ½-inch thick, the same as the drywall used on most residential walls. But the QuietRock version has two thin layers of paperbacked gypsum, plus the sound-dampening layer in the middle. It’s $54.98 a sheet at Lowe’s, compared with about $13 for regular ½-inch drywall.

QuietRock also makes ⅝-inch-thick panels that, unlike the ½-inch ones, don’t have paper between the two sheets of gypsum. Marketed as EZ-Snap or QuietRock ES, these panels can be cut to shape by scoring with a utility knife, then snapping into a fold, as with regular drywall. Panels that have paper in the middle need to be cut with a saw, which creates more mess and hassle. The QuietRock website, quietrock.com, has a find-a-dealer feature, which helps customers locate suppliers.

Ehrlich said it’s possible to make a homemade version of QuietRock by sandwiching two layers of regular drywall with Green Glue noiseproofing compound between them. You’ll need two 28-ounce tubes of the caulk-like compound for each 4-by-8-foot sandwich. (A case with a dozen is about $317 at Acoustical Solutions.) Install one layer of regular drywall, then squirt a bead of the compound on the back of the other sheet, a few inches in from the edges and in a random but fairly uniform pattern. Then screw that panel to the first layer where the screws will bite into studs.

Another space-saving solution would be to remove the existing drywall and install mass-loaded vinyl or a rubber sheet product to the studs, then top that with a new layer of drywall. Mass-loaded vinyl is a thick, heavy, rubberlike material. A 4-by-25-foot roll of AudioSeal sound barrier that’s ⅛-inch thick costs $172.99 at Acoustical Solutions; it weighs 100 pounds and covers about 100 square feet. The Peacemaker sound barrier, which is similar but made from recycled rubber, is $110 for a roll the same size.

If you don’t care whether you lose the space filled by the existing drywall, it still makes sense to remove it before installing the membranes. Having the sheets hang slightly limp behind the new drywall helps shed sounds that might otherwise pass through the wall.

And with any of the alternatives, it’s important to seal edges with acoustical sealant. If the wall has any electrical outlets or light switches, you’ll want to wrap the back and sides of the box with soundproofing material, such as ATS Acoustics putty pads ($37.35 for a box of 10 on Amazon).

If all of these seem like more work or expense than you’d like to undertake, there are also options for drowning out your neighbor’s snores: earplugs, noise-canceling headsets and white-noise machines.

Have a problem in your home? Send questions to localliving@washpost.com. Put “How To” in the subject line, tell us where you live and try to include a photo.

Loading...