Silence is Golden

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Your average house is a very noisy place to live. Forget crying babies and vocal teenagers; think of all the fans, blowers, pumps, HVAC equipment, washers, dryers, dishwashers, refrigerators, freezers — cycling on, cycling off, all day long. Home offices and media rooms add to both the noise level and the need for quiet.

January 01, 2006

 

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Your average house is a very noisy place to live. Forget crying babies and vocal teenagers; think of all the fans, blowers, pumps, HVAC equipment, washers, dryers, dishwashers, refrigerators, freezers — cycling on, cycling off, all day long. Home offices and media rooms add to both the noise level and the need for quiet. Apartment, condo and townhome residents, who share walls, floors and ceilings with each other, end up knowing more than they care to about the family next door. Even in single-family homes, the trend toward smaller lots and infill housing brings the neighbors' noises inside.

 

Ideas for Reducing Noise

You can't do much about the noisy kids, but you can do a lot to absorb, reduce or eliminate other indoor and outdoor noises that grate on your clients' nerves.

Happily, what makes a home quieter usually makes it more energy efficient — which makes it more comfortable and affordable, too. The appliances, windows, HVAC, fans, insulation and air sealing methods you choose will make all the difference.

Prevent inside noises from traveling

Absorbent materials. If you're doing an interior remodel that involves little structural change, consider installing materials that absorb, rather than reflect, sound. That could mean putting down carpeting or cork flooring, or advising a client to consider an interior design solution such as moving or changing furniture or drapery. These techniques will reduce sound coming from a source within the room.

Keeping interior sound from traveling around a home or between multifamily units requires retrofitting or rebuilding walls and floors to improve their STC (sound transmission class) and IIC (impact isolation class) ratings. STC ratings measure airborne sound; IIC ratings measure structure-borne sound. Both indicate by how many decibel levels a building material or assembly reduces noise.

According to the National Institutes of Health, normal conversation ranges from 50 to 65 decibels, and prolonged exposure to any noise above 90 decibels can cause gradual hearing loss. Sound requirements vary by code and by structure, but it's not uncommon for interior walls to have STC ratings of 15 to 35.

Walls. An uninsulated interior wall with ½-inch wallboard, framed with 2×4 wood studs 16 inches on center, has an STC rating in the low to mid 30s. Adding 3 ½ inches of fiberglass batt insulation can bring that up to 38, according to the North American Insulation Manufacturers Association.

You can also increase the STC ratings by using 5/8-inch drywall or by using a double layer of wallboard on one or both sides of the wall. The disadvantage to this option is losing floor space.

Adding resilient channels in the walls or using double framing are still more effective methods, though more labor intensive.

Interior doors should have STC ratings near that of the walls. If your client has hollow-core doors, upgrading to a solid-core option is an obvious option for isolating sound.

Floors. Installing a carpet and pad not only absorbs sound, it reduces impact noise and increases IIC ratings. For areas where carpeting isn't wanted, a floating floor with a sound-isolating mat under the finish floor does the job. Insulation and resilient channels are also options.

Air Sealing. Flanking paths are the routes by which sound travels. Walls with high STC ratings won't reduce sound as much as they should if the walls have unsealed penetrations.

Look for air leaks in and around doors, plumbing chases, electrical outlets, attic accesses and dropped ceilings.

Carl Seville, an Atlanta remodeler turned green building consultant, has five specific recommendations:

  • Around receptacles and switches, use foam gaskets under plates.
  • At wall to floor connections, caulk between baseboard (or drywall) and floor. Pull back carpet, caulk and reinstall if needed.
  • Use commercial products to seal around attic access hatches and stairs.
  • Replace leaky recessed lights with airtight models and install airtight trim, or build a box over them and then cover with insulation.
  • Also seal around HVAC registers and surface light fixtures.

Check the ducts themselves. Many duct layouts leak 10 to 20 percent of the conditioned air. Older ducts can leak as much as 50 percent, requiring the heater or air conditioner to work that much harder. Seal all ducts and plenum junctions with mastic or aerosol sealant.

Keep outside noises from entering

Windows and doors. These openings in the building envelope are the most obvious ways for transportation noise and other obnoxious sounds to enter the home. The same features of windows that enhance their energy performance — multiple glazing layers, specialty gas fills and insulating frames — serve to dampen outdoor noise as well. Energy Star qualified windows will cost 5 to 15 percent more than the lower-performing alternatives, but they can also reduce home heating and cooling costs by $125 to $340 a year (depending on climate), compared to older single-pane windows. If you'd prefer to keep an older window because it's visually appealing, interior storm windows will provide an extra sound and air barrier. Acoustical windows with laminated glass are your best bet.

Proper installation will prevent noise and the elements from entering the home. "Use proper flashing at the top, sides and bottom, and use caulk or low expansion spray foam insulation between the window and the framing to eliminate air leakage," says Seville.

Air sealing. Air seal the entire building envelope, not just around windows. In addition to being a source of noise, air infiltration can cause draftiness, moisture and dust problems and account for up to 30 percent of a building's heating and cooling costs.

Look for air leaks in and around windows, doors, chimneys, chases and other penetrations. Use caulk for sealing gaps of less than ½ inch. Spray foam can be used to fill small holes, as well as large cracks. You can even use expanding foam around windows if the product is designed specifically for this task. Use weatherstripping to seal areas with moveable components such as windows and doors.

For larger areas, use housewrap or 15# felt paper to form an airtight seal over the exterior sheathing, and polyethylene plastic to seal complicated leakage areas that may be of irregular shape.

Insulation. When we think insulation, we think about keeping out unwanted heat and cold. But proper insulation and leak-proof construction also dramatically reduce the amount of noise that enters the home.

If using fiberglass insulation, don't cram it into corners or stuff it behind pipes. Batts must completely cover the wall before you hang the drywall. Thoroughly air seal before installation. Cotton batts, made from recycled blue jeans, make a slightly more effective noise barrier than fiberglass. Cellulose insulation, made of fire-treated recycled paper products blocks sound more effectively than fiberglass because of its greater density.

Spray foam insulation, though more expensive, is an even more effective sound and air block because it expands into tight areas before it dries. It saves time on the remodeling schedule by eliminating the separate air-sealing step. Closed-cell spray foam insulation has a higher R-value than open cell, but is more expensive and doesn't absorb moisture or allow water to pass through it. Don't use closed cell under a roofline, says Seville, where it could mask a leak.

Eliminate noise at the source

Kitchen and bath remodels, room additions and whole-house remodels offer the opportunity to replace loud appliances, fans and HVAC equipment with quieter options. It takes energy to make noise, so if one of these items is noisy, it's also likely to be inefficient.

Appliances. Older refrigerators, dishwashers and room air conditioners tend to be sonic offenders. By installing Energy Star-qualified appliances you'll eliminate a lot of the hum and whir that you find in nonqualified models.

Fans. Noise prevents many homeowners from using exhaust and ventilation fans. Ultra-quiet models are now widely available, and they often provide the best ventilation. Many furnaces have quiet variable speed fans. Some bathroom fans are virtually silent. Many kitchen range hoods are so inconspicuous, you need an indicator light to know they're running. Fans that produce under 1 sone, or unit of loudness, are very quiet.

Inline fans, where the fan is mounted along the exhaust duct, are also available. They are frequently quieter because the fan is further away from the bathroom or kitchen.

HVAC equipment. If you're installing a new HVAC system, you have several options for finding a quiet one. if you're looking for a quiet condenser, choose an Energy Star qualified system with a nominal sound level of 76 decibels or less. Locate the condensing unit where it will be the most unobtrusive. Make sure walls or landscaping features do not block airflow to the unit because that would reduce its efficiency.

Be sure that heating and air conditioning equipment, including blowers and ducts, is sized correctly. "Right-sized" units operate less frequently, more quietly and more efficiently. Use the Air Conditioning Contractors of America Manual J to determine the correct size. Properly sized, any system will turn on less frequently, producing less noise.

Radiant floor heating uses pipes buried in the floor to pump hot water and produce heat, avoiding all the blowers, ducts and banging baseboards of a conventional heating system.

The quietest home conditioning system is passive solar, which heats the home's walls and floors with solar radiation. Concrete and other dense walls, like stone and brick, store heat during the daytime for release at night. During the summer, nighttime ventilation cools the walls and reduces the need for daytime air conditioning. Passive solar homes also don't usually require noisy blowers, ducts and baseboards.

If you've incorporated many of these features, you'll know that you've done your best to make your client's home as quiet as possible.

That is, unless you're willing to take the client's kids with you, too.

The Partnership for Advancing Technology in Housing (PATH, www.pathnet.org ), is administered by the U.S. Department of Housing and Urban Development.

 

For More Information

The following resources provide more specifics, including-construction detail drawings.

Sound Control, "Best Practices Guide to Residential Construction," by Steven Bliss, John Wiley & Sons.

"Noise Control Manual for Residential Buildings," by David A. Harris, McGraw-Hill.

"The Noise Guidebook," 

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