Reducing noise levels within the home

Noise…sometimes it might be just a little annoying, other times it might be quite distracting. But, regardless of what effect noise might have on your home, it is part of everyday life.

If you are forced to raise your voice to communicate with someone standing less than one metre (3 ft.) away, the noise level in the environment is too high.

Fortunately, there are several ways to reduce noise levels within your home.
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Types of noise
Soundproofing a room
Windows
Walls and Ceilings
Floors
Doors
Bathrooms
Soundproofing against external noises
Helpful tips

Types of noise

In order to adequately counteract the effects of noise, it is important to understand the nature of sound and how it behaves. There are two types of noise:
  • Structure-borne noises: These sounds travel through structures and create vibrations, which, in turn, cause vibrations in the air. Part of the noise is absorbed by the structure itself but the remaining sound waves travel through the rigid joints within the home. (Ex: A pipe in the basement is vibrating against a joist, which in turn is connected to the studs of a load-bearing wall on the ground floor, which is located under the floor of a room on the first floor… and it sounds as if the pipe were knocking directly in the room.) In this category, you will find such noises as: footsteps, the slamming of doors, the knocking of old valves and pipes, falling objects, and the sound of chairs being dragged across the floor.

  • Airborne noises: These sounds travel through the air before generating vibrations in household walls and windows, which in turn create vibrations in the air in the next room. The original noise "collides" with the surface (Ex: wall, window, etc.) and part of the sound is reflected back towards the source; another part is absorbed by the material and the remaining sound escapes into the air in the room on the other side of the surface. Music, voices, dogs barking, and noises made by passing traffic are a few examples of airborne noise.

These two types of noise will obviously require different solutions.

When dealing with structure-borne sound, the idea is to absorb as much as possible, and then prevent it from traveling by installing shock absorbers between the structures and their finished surfaces. Airborne sound, on the other hand, is transmitted through window glass, thin partitions and openings both large and small (if air can travel through something, so can sound). This type of scenario will require the elimination of air inlets and the selection of materials that reflect and absorb sound waves.

Of course, soundproofing relates not only to preventing sound from entering a room, it must prevent sound from escaping the environment as well. You will be pleased to know that interior soundproofing techniques remain the same regardless of the situation.

Soundproofing a room

Installing the most comprehensive soundproofing system, one that prevents sound from entering and escaping (also called acoustic insulation), is a large-scale project where the wall, floor and ceiling coverings must all be removed, and old doors and windows must be replaced.

Windows

In terms of noise transmission, windows are the weakest link in almost every home. In fact, when it comes to noises generated by external sources, walls are rarely to blame but windows are always part of the problem.

Because of this, window quality has a direct impact on the noise levels generated by external sources. Regardless of whether you are looking at single-pane or double-pane windows, pay particular attention to glass thickness and density (the heavier the glass, the better the window). Ask your expert for information on window frame construction and the materials used (the heavier…). Modern windows always come equipped with flexible weatherstripping, which not only prevents cold air from entering the home but also insulates the window frame from any direct contact.

Perhaps you live next to the highway, or are the drummer of the next great rock band? If so, you might want to invest in windows that provide maximum soundproofing: custom-made thermal windows. They may be a more expensive solution than standard windows but they are also more effective.

This type of window is built as follows: a pane of glass, a sheet of plastic film, another pane of glass (the sheet of plastic film is sandwiched between two panes of glass), an air gap of approximately 1.3 cm (0.5 in.), and, finally, another pane of glass (or, if your budget allows, another thermal glass assembly - glass/film/glass). This type of thermal glass is similar to the glass used on car windshields.

Walls and Ceilings

To ensure the proper level of acoustic insulation in your walls and ceilings, it is recommended that acoustical wool be installed between wall studs (and between ceiling joists), and that a bead of acoustical sealant be applied on the front of each stud.

Fasten acoustical panels (Sonopan) onto the studs (the previously applied sealant will prevent the panels from vibrating on the studs), and apply another bead of acoustical sealant around the perimeter of each panel. Once this is done, the resilient channel is installed to prevent any direct contact between the panel boards and the studs.

Because the weight of the material also affects the way sound travels, it is preferable to install two layers of panel board. Make sure to stagger the joints and apply plaster to the joints on both layers of panel board. This part of the installation is completed by applying a final bead of acoustical sealant between the wall and the floor (which will later be hidden by the baseboard). We now have a wall that reflects any sound produced in the room, that absorbs the airborne noise and that limits the transmission of structure-borne noise.

Note: If you intend to undertake this project, follow the steps included in the soundproofing of walls and ceilings section found under the Renovation and Construction heading.

Suspended ceilings made of acoustical tiles do not require any alteration of the actual ceiling but will not be as effective as the above-mentioned approach. This being said, adding the effects of the suspended ceiling to those of previously installed ceiling insulation will provide better results. It is important to note, however, that acoustical tiles should not be painted: their sound absorption properties are tied to their porous construction and by painting them (and covering the holes in the tile surface), the effectiveness of the material will be diminished. If you must paint a suspended ceiling, apply a single coat using a roller.

Floors

If you intend to soundproof your floors, and must remove the floor covering in the process, take the time to securely fasten any plywood panels that might be squeaking.

At this point, it is recommended that you install a soundproofing membrane before installing the floor covering. There are several different types of membrane available, including models made of rubber particles, cork and synthetic materials. Cork insulators, though long used for this type of application, no longer provide the same performance as more recent technologies.

Pressboard panels must then be installed on top of the rubber particles membrane, especially if you intend to install carpeting or ceramic tiles.

Note that these different membranes do not reduce the level of airborne noise: they are designed to reduce the level of impact noises and prevent them from traveling. Due to its heavy, thick and rigid construction, pressboard, on the other hand, does contribute to airborne noise reduction.

If you would like to effectively reduce airborne noise, while improving structure-borne noise reduction (Ex: If you practice a musical instrument that transmits its resonance through structures, such as a drum kit, cello or piano), you might want to build a "floating slab" (not to be confused with a floating floor).

This is done by covering the existing floor with a sound-absorbing membrane, and then gluing resilient supports (Ex: rubber blocks) at regular intervals on the pressboard panels, before inserting acoustical wool between the supports. This structure is then laid on top of the existing floor so that both "floors" are then separated by a membrane, a shock absorber and a sound-absorber. Install a second acoustical membrane on the second floor and then install the floor covering (or you may also choose to install another layer of pressboard and then the covering).
To ensure that this entire construction is installed without any solid material entering into direct contact with any of the walls, a bead of acoustical sealant must be applied between the walls and the floor. The baseboards must not touch the floor either.

The rubber blocks and acoustical wool may be replaced by a 4 cm (1 ½ in.) slab of concrete. Though concrete has different acoustic properties, it is just as effective.

Keep in mind that installing a "floor over the floor" will raise your floors by between 5 and 10 centimetres (2 to 4 inches), and that the bottoms of your doors must be cut to size as a result.

Although it may be outdated as a soundproofing membrane, cork is being used more and more as a floor covering (no, it doesn’t look like a bulletin board was installed on your floor; it looks more like wood). Installing this type of floor covering, on top of a soundproofing membrane, or on a floating slab, only improves the level of acoustic insulation.

Note: If you decide to nail the floor covering to the floor, you are, in effect, neutralizing much of the soundproofing work you just completed as sound will travel through the nails. Better to use floor coverings that are held in place with glue or install floating floors.

Doors

Doors, much like windows, represent weak links in the soundproofing chain. They are often hollow and allow noise to travel through them quite easily. If you are looking for a door that is truly effective for reducing noise levels, choose a solid door. Keep in mind, however, that installing a solid door is useless unless you have completed the acoustic insulation projects on your walls as described above.

In order to absorb the impact when the door is closed, and to prevent sound from passing through as well, install weatherstripping along the entire door moulding.

Then, plug the opening between the floor and the door (otherwise, your weatherstripping installation will have been done for nothing). This is done by bunching a carpet or blanket at the foot of the door to temporarily block the gap between the door and the floor. For a more permanent solution, install a falling doorsill. This type of mechanism automatically drops a doorsill into place to block the opening when the door is closed. Theses devices are designed to not cause damage to your floors. Better yet; install an actual doorsill on the floor to ensure that all sides of the door come to rest against weatherstripping when the door is closed.

End result: All spaces where sound might pass have been eliminated, there is a rigid, heavy and thick surface in place to reflect sound, and weatherstripping has been installed to prevent any direct contact between the door and the frame.

One last thing: Apply a bead of sealant between the moulding (the one the door rests against when closed) and the doorframe (upon which the moulding is fastened), or sound may still get through.

Bathrooms

Many people think it useless to close in a wall behind the shower, but that would be a mistake. It is an avenue for noise to get out!

Before installing your shower unit, install acoustical wool between the studs, like you would on a standard wall. Then, close the wall in using one or two thicknesses of waterproof wallboard. Warning: Make sure that the shower you selected can be installed against a finished wall.

Keep in mind that the unit you select will also have an impact on the level of soundproofing: some showers come equipped with a soundproof base, which reduces the level of noise generated by the water falling from the showerhead. As for bathtubs, those made of acrylic will be less noisy (they tend to dampen the "water-noise" effect during baths) than steel constructions but the ultimate soundproofing weapon is without a doubt a cast iron tub.

Soundproofing against external noises

During the construction or renovation of your home exterior, it is important to know that the heavier the covering material, the better the soundproofing. This means that a brick house is much better protected from a "sound assault" than one with vinyl siding. And a home covered in solid stone will provide better soundproofing than one made of hollow bricks…unless of course the stones make up the entire thickness of the walls, like in the old days.

In addition to providing privacy, mature trees and other forms of vegetation also absorb their fair share of noise (not much of course but every little bit helps!).

Finally, for residences located next to highways and other noisy areas, specially designed free-standing walls may be installed to reduce noise levels; ask your municipality for more information. Keep in mind however that these walls must be installed with a minimum height of 3.6 m (12 ft.) to be effective.

Helpful tips

If you are not prepared to undertake large-scale projects, perhaps some of the following tips will help reduce noise levels in your home. Please note that these are not soundproofing solutions. These solutions relate to acoustic absorption and, as such, will not eliminate sound transmission. They will simply help to reduce sound intensity; particularly for high frequency sounds (they have little effect on low frequency sound waves). Should these measures prove insufficient, acoustic insulation solutions, as described above, will be required.

Fabrics not only absorb sound, they prevent them from being reflected as well. This is why bedrooms are usually acoustically "muted" as they often include full-length curtains made of thick fabric, at least one bed, and perhaps even carpeting. Use the bedroom principle on other rooms in your house:
  • Install full-length curtains made of heavy fabrics such as velour, certain types of canvas or even cotton (avoid using light or delicate fabrics). Using some creative decorating ideas, you can take the concept one step further by covering your walls with curtains and hanging fabric from your ceiling. In addition to absorbing a few decibels, this technique will help you eliminate the echo and create the impression of a quieter room.

    Another helpful hint: If you come across a hotel under renovation, ask if the curtains will be changed and, if so, what they intend to do with the old ones. Most hotels use acoustic curtains and, though they may be a little worn, you can easily hide them behind your "real" curtains.

  • Assess your furniture to determine if any of the pieces may be made less sound "reflective". Placing a tablecloth on a table and some cushions on the chairs will help reduce sound reflection.
  • A nice, thick decorative rug placed over the floor can add a nice touch to room decor while helping to dampen the echo effect.

  • It is recommended that at least 25% of the room be covered in fabric (couches, curtains, carpeting, etc.) in order to significantly reduce the level of echo.

You can also try to reduce noise levels at their source:
    • Lower the sound on the television
    • Use headphones
    • Install floor protectors under chair legs
    • Place pieces of carpet under stereo speakers (or under the portable stereo unit), or install them on stands or in specially designed units and move them away from common walls
    • Add some distance between noisy devices and common walls
    • Buy toys with volume control
    • Remove shoes (especially high heels!) and wear slippers
    • Make sure that the bottom of the supports (legs) on large appliances, such as the washer, are made of a shock absorbing material (such as rubber) and are in good condition. If not, slide a piece of carpet or specially designed support system under the feet of the appliance. By adding a rubberized carpet, in addition to the shock absorbers, you can greatly reduce vibrations.
Has your teenager invaded the basement and claimed it as his home? Would you like to create a "vault" where he can play his music without disturbing the entire household? The installation of a suspended acoustic tile ceiling, along with the addition of soundproofing in the ceiling, walls and basement floor, and the installation of soundproofing in the floor of the room above the basement, would represent the ultimate solution. Perhaps not within everyone’s budget but extremely effective nonetheless.

Choose your projects according to your budget and the possibilities within your home: If noises are interfering with your daily life, there is always a solution. Whether to lessen their effects, absorb them or limit their ability to travel, your local expert (construction, floor coverings, plumbing departments, etc.) can help you decide; it’s their job to be aware of new soundproofing products as they become available.
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