Soundproofing a Room or Apartment: What Works

By HomeSmitten Team ·

A Guide to Soundproofing a Piano in an Apartment

The quick answer

Blocking sound takes mass, an air gap and sealed gaps. Soft furnishings only improve the sound inside a room. Start by sealing leaks, because even a small opening ruins a good barrier. Plants on a balcony help very little. For a piano, a silent model or headphones works better than padding. Level a washing machine before buying pads. For windows, laminated glass has the best published data, and a deep air gap matters as much as the pane.

Most noise complaints in an apartment come from a few places: the window, the shared wall or floor, and one noisy appliance or instrument. Fixes that help the sound inside a room, like rugs, do very little for noise passing between rooms. Picking the right type of fix saves money.

This guide gives the basics first, then five common problems: balcony noise, a piano, rain on a caravan roof, a washing machine, and laminated glass versus acrylic for windows. Where a number comes from a seller or a single test, we say so. Where we found no usable data, we say that too.

Blocking Versus Absorbing Sound

There are two different jobs. Soft, porous materials absorb sound and cut echo inside a room. GIK Acoustics, a panel maker, says acoustic treatment improves the sound within a space and only somewhat dampens sound bleeding into the next room. It says the only real way to keep sound from passing through is mass, and describes extra walls with an air gap and insulation.

Two ratings help you read product pages.

  • NRC (noise reduction coefficient) rates absorption inside a room, on a scale of about 0 to 1.
  • STC (sound transmission class) rates how well a wall, door or window blocks airborne sound. Riverbank Acoustical Laboratories, a testing lab, lists these rough meanings: at STC 25 to 30 speech is easily understood through the partition, at 35 to 45 loud speech is audible but less intelligible, and at 50 to 55 normal speech is private but loud sounds are still audible. For a barrier, STC is the number to look at.

Gaps decide the result. A lab rating assumes a sealed edge: Riverbank notes labs seal the perimeter of a test sample with mastic to limit flanking. A DDS Acoustical article gives an example of how fast gaps hurt. A 5% opening in a partition with a theoretical 40 dB transmission loss drops it to 13 dB. A window maker says even 1% opening can cost up to 10 dB. Before you buy anything heavy, seal the gaps around doors, windows and where walls meet floors.

Balcony and Street Noise

Best noise-blocking and sound-absorbing plants

Plants are the most common advice for balcony noise and the weakest. A US Forest Service study of how trees scatter sound found only "small noise reductions" from sound passing through a stand of trees, and warned that trees can even reduce a barrier's effectiveness. That study looked at trees along roads, not pots on a balcony, so a few potted plants can't be expected to do better. Plants are fine for looks and a sense of calm. They will not cut traffic noise by an amount you'll notice.

What does work is a barrier that blocks the line between the noise and your door. Research on balconies at Hong Kong Polytechnic University describes the balcony working as a screen that blocks the direct line of sight between the noise source and the facade, and found that the ceiling and its reflections matter. So an open balcony is already a partial screen, and its parapet and ceiling both matter.

  • Close the gaps first. If the balcony door or window leaks air, it leaks sound. Seal around the frame and fit a draft seal at the bottom of the door.
  • Add a solid, tight screen, not a gappy one. A solid panel at the railing blocks more than slats or mesh. This follows from how barriers and gaps work (judgement), and we found no measured figure for home balcony screens.
  • Treat the balcony ceiling. Because ceiling reflections matter, an absorbing layer on the ceiling above the seating area makes sense (judgement from the research above).
  • Glazing is the strongest option. A glazed balcony or window insert is the route that can make a measured difference. See the glass section below.

Piano in an Apartment

How to soundproof a piano room and apartment

A piano is loud, and it also sends vibration into the floor. Padding the room helps a little but won't stop a neighbor hearing it. Check your lease first. Many leases and building rules set quiet hours or limit instruments, and a rule you break costs more than any soundproofing.

  • Know where the sound comes from. A piano specialist explains that most of an upright's sound comes out the back, because that is where the soundboard is. A piano pressed flat against a wall sounds muffled, which is why specialists advise a few inches of gap.
  • Place it on an interior wall, away from the neighbor's wall. Thomann, a large music retailer, advises an interior wall and about a hand's width of space behind an upright for air circulation. Putting the piano on a wall you don't share is our judgement for reducing what the neighbor hears.
  • Add soft surfaces. Thomann suggests a carpet and curtains to soften a bright or hard-sounding piano. Yamaha's published soundproofing tips list thick carpet, heavy curtains and sealing gaps at windows and doors, and mention a sound-insulating board behind an upright. We couldn't open that Yamaha page ourselves, so check its wording directly.
  • Isolate from the floor. Rugs and felt pads under a piano reduce some floor-borne vibration, but we found no tested figures. Treat them as a modest help, not a fix (judgement).
  • If neighbors still hear it, change the instrument or the hours. A digital piano or a silent-system acoustic piano with headphones removes the problem. Practice only at agreed hours.

Before you add anything to the inside or back of the instrument, ask a piano technician. We found no source that supports DIY padding of the piano itself.

Rain Noise on a Caravan or Van Roof

How to reduce rain noise on campervan roof

Rain on a thin roof makes the panel ring like a drum. Two things reduce that: damping the panel, and adding mass and insulation inside. Moisture is the risk, so read this section before sticking anything to a roof.

  • Check for leaks first. A caravan dealer separates condensation (moist air meeting cold surfaces) from damp (water entering through exterior seals). Drips and stains point to a seal. Check roof seals and vents before blaming noise on the roof itself. A motorhome insurer also advises inspecting roof seals and vents before rainy seasons.
  • Damping mats. The same insurer describes butyl-and-foil mats as good for vibration and structural noise, working best on large, flat surfaces like the roof. It suggests cleaning the roof, applying mats with full coverage, then adding mass-loaded vinyl for airborne sound.
  • Choose insulation that doesn't hold water. A vehicle insulation seller says to avoid materials that absorb water, such as wool or felt, and prefers closed-cell foam, with a vapor barrier and good ventilation. This is a seller's advice, so confirm it with your caravan maker.
  • Keep ventilation working. Dealers advise keeping vents unblocked, using night-vent window settings, and ventilating after steam from showers or cooking.

What we couldn't find: independent testing of how many decibels any of these remove from rain noise, so we don't promise a number. Don't seal a wet roof, and don't cover vents, roof lights or seals. Many caravans have manufacturer rules about drilling or adding material to the roof, so check your handbook or dealer before you start.

Washing Machine Noise

How to dampen washing machine sounds and vibration

Most washing machine noise is vibration, and most vibration comes from three fixable causes. Manufacturers' support pages agree on the order to fix them.

  1. Shipping bolts. Samsung says these rear transit bolts must be removed before use. Electrolux lists the same check first. LG says to remove all four on a new install.
  2. Level the machine. Samsung says an uneven surface is one of the most common reasons for noise and vibration, and tells you to lift the machine slightly and adjust the lowest foot, then lock the feet. LG says the slope under the machine must not exceed 1 degree and all four feet must rest firmly on the floor. It advises quarter turns and tightening the locknuts afterward.
  3. Balance the load. Samsung warns that washing one heavy item alone, like a bath mat or jeans, can cause excessive noise, and so can overloading. Electrolux warns that unusual loads such as trainers raise vibration.

Floor and pads. Samsung says to use a level, solid floor, to reinforce wooden floors, and to avoid carpet or soft tiles. Electrolux suggests anti-vibration covers under the feet and leaving space between the machine and cupboards or walls. Pads are a second step after leveling, not a replacement (our reading of the order the support pages give).

What not to do. Don't wrap or box in the machine, and don't cover vents or gaps (judgement for heat and fire safety, so follow the manual). If the noise starts suddenly during normal use and these steps don't fix it, Electrolux says to call a service engineer.

Laminated Glass Versus Acrylic for Windows

Laminated glass vs plexiglass: most effective soundproofing material

Both are used as a second pane placed inside an existing window, with an air gap between. What matters most is how well each pane damps vibration, how heavy it is, and how well it seals.

  • Laminated glass. Saflex, a maker of acoustic interlayers, says laminated glass with an acoustic PVB interlayer damps sound because of the elastic behavior of the PVB layer between the panes. It says a properly designed Saflex Acoustic build can reach about STC 50, compared with about STC 30 for a standard 4 mm / 12 mm air / 4 mm insulating unit. That is a manufacturer's claim for a designed configuration, not a result you get from any laminated pane.
  • Acrylic. Acrylic is lighter than glass of the same thickness (judgement from material density). We found no independent lab STC figure for acrylic secondary panes that we could open, so we won't quote a number. Ask the seller for an ASTM E90 or ISO test report for the exact build and air gap.
  • The air gap matters. A secondary glazing maker reports that larger gaps between panes reduce resonance and improve performance, with test results for cavities from 50 mm to 200 mm. It also describes acoustic laminate glass as aimed at high-frequency noise.
  • Sealing matters as much. The same maker warns that even a 1% opening can reduce insulation by up to 10 dB. A well-sealed frame with a thinner pane can beat a thick pane with leaks.

Judgement call: for low rumble like trucks, heavier and well-damped glass has the advantage on the physics. For a renter, a removable acrylic insert is lighter, easier to fit, and allows a deep air gap. Whichever you choose, compare lab reports for the same air gap, and check the seal before the pane.

Frequently Asked Questions

Do plants on a balcony reduce noise?

Only a little. A US Forest Service study found only small noise reductions from sound passing through a stand of trees. Pots of plants on a balcony are smaller still. A solid screen and sealed gaps do more.

How do I stop a washing machine from making so much noise?

Remove the shipping bolts, level all four feet and lock them, and balance the load. Samsung and LG both say an uneven machine is a common cause. Anti-vibration pads can be added afterward. If the noise starts suddenly, call a service engineer.

Is laminated glass better than acrylic for soundproofing?

Laminated glass has the best published data: Saflex reports about STC 50 for a properly designed acoustic laminate versus about STC 30 for a standard insulating unit. We found no independent lab figure for acrylic, so ask for a test report for the exact build and air gap.

Can I soundproof a piano in an apartment?

You can reduce it but not remove it. Keep it off a shared wall, a few inches from the wall behind, with carpet and curtains nearby. A silent-system or digital piano with headphones removes the problem. Check your lease for quiet hours.

Does insulation stop rain noise on a caravan roof?

It can reduce it. Damping mats and mass-loaded vinyl are the usual suggestions. Avoid absorbent materials like wool or felt that can hold water, check roof seals for leaks first, and keep vents clear.

Sources