It’s a
common complaint among city-dwellers that the walls and floors separating one
apartment from another allow sounds from one side to pass too easily through to
the other.
Loss of
acoustical privacy hasn’t been a grievance in the suburbs until recently; as
land prices increase, lots are getting smaller and houses are getting closer
together. Houses are also getting closer to the street and its associated noise
pollution. And attached condominiums are being built at a rapid pace – your
next-door neighbor may be just on the other side of the wall.
It’s more
critical now because so many of us have powerful multi-media centers in our
homes, and we like to enjoy our movies with the sound turned up high.
The
closer you live to your neighbor, the greater the opportunities for a loss of
acoustical privacy. How can you keep the sounds of your daily life from
bothering your neighbors and theirs from bothering you?
Hear Ye,
Hear Ye…
Sound is
transmitted from its source to the ear by waves traveling through the air. The
volume of the sound when it reaches you is affected by the distance from the
source and the presence of obstacles between the source and the ear.
It’s
those obstacles we’re concerned about – how can we make them stop the sound
waves?
Some
materials are better at attenuating sound energy than others; generally the
thicker or more massive the material the more sound energy it absorbs. But
placing big, thick, heavy materials between living units can be impractical and
expensive, especially if you’re remodeling an existing home.
Fortunately
there are some easy and inexpensive ways to build good “soundproof” walls and
floors and to greatly improve the sound characteristics of existing construction.
Air Lines
When a
sound is created on one side of a wall or floor, the energy causes the building
materials to vibrate; if that material is a thin, flexible material such as
drywall or wood flooring, it picks up the vibration and easily transmits it to
the next material in the assembly.
If the
next material is air – in a hollow wall or floor assembly for example – then
air vibrates, continuing the transfer of energy to the next material. Much of
that sound energy can be stopped simply by filling the air space with
insulation such as fiberglass batts or cellulose. The “loose” nature of
insulation doesn’t transfer energy well and does a very good job of reducing
the volume.
Small
openings in walls are a big source of sound transfer. Light switches and electrical
outlets are installed in cutouts in the drywall and are often aligned directly
across from each other. When the electrical boxes are installed, there’s no
room for sound insulation. The solution is to move one of the switches or
outlets so that they’re not aligned and allow room for insulation behind them.
It’s a small detail that can help a great deal.
To reduce
the sound leakage even more, caulk the electrical boxes to the drywall to
eliminate any air passages from the outside to the inside of the wall. On
exterior walls the same concepts apply – insulate and seal all small openings
to reduce noise.
Good
Vibrations
But
blocking air space is only part of the solution. When building materials touch
each other they vibrate and transfer sound energy very effectively. There are
some specialized materials and a few basic techniques you can use to separate
building materials from each other that work in new construction and
remodeling.
An
acoustic mat is a thin pad that can be rolled out on the floor like carpet
padding. It’s placed under a wood floor or under carpeting and helps separate
the building materials from each other. Some types of acoustic mats can be
installed in walls under the drywall. Either way, an acoustic mat “breaks the
connection” between building materials and helps reduce sound transfer.
In new
construction and remodeling, a common technique is the use of stand-off clips,
metal strips that attach to wood framing. The drywall is then attached to the
strips instead of the wood; as sound energy causes the drywall to vibrate, the
clips absorb the energy before it is transferred to the framing.
An even
more effective but somewhat more expensive solution is a staggered-stud wall.
In this framing technique, two parallel walls are built with offset studs; the
walls “nest” into each other without touching, and the interior finish is only
attached to one side of each wall. This completely separates the materials and
is very effective when combined with sound insulation.
Quiet As
A House
Although
there are many high-tech sound insulation products on the market, they’re not
always needed to significantly quiet a home. Simple and inexpensive techniques
can eliminate most unwanted sound from adjacent living units, next-door
neighbors, and noisy streets.
Refer :
Richard
L. Taylor, AIA is a published author and recognized expert in Residential
Architecture. He is President of Richard Taylor Architects, a 5-person firm in
Historic Dublin, Ohio that specializes in custom and luxury home design, and
remodeling and room addition projects of all sizes. Residential Architect - Luxury Home Plans - Luxury House Plans
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