Spray away apartment noise
QUESTION: I own a triplex in an older part of town that is divided into three apartments, one on each floor. The building is a rock-solid 1950s-era wood frame construction, with a brick exterior, and is in excellent shape in almost every aspect. The problem is there is some noise leakage between the main and secondfloor apartments. Although not severe, the recent tenants have asked if something could be done. The main-floor tenants don’t like the footsteps above, while the top floor tenants don’t like hearing the muffled TV and voices below.
The floor consists of twoby-10 joists with three-quarter-inch plywood underlay and hardwood on the top floor with a single layer of drywall on the ceiling below. There is a little ductwork for the forced air furnace weaving its way between a couple of the joists. I am willing to do a major overhaul on the ceiling, including ripping the drywall out if necessary, but was wondering if you had any suggestions on how best to soundproof that space.
I was thinking of first ripping out the drywall ceilings and then placing batt-type sound insulation between all the joists, replacing the drywall and adding a second layer of drywall with one-by-three strapping as a spacer.
Don Christie, Ottawa
ANSWER: Noise transferring through floors of multi-family dwellings is a common complaint of tenants or homeowners, particularly wood frame buildings like your triplex. You may never be able to stop all noise transfer between the suites, but you are on the right track with your idea of increasing the insulation between the floors to prevent sound transfer. I will comment on your suggested method of insulation and provide a few more suggestions for improving the situation.
There are two main items to keep in mind when attempting to stop sound from transferring between the suites in your rental home. You have unknowingly identified both of these in your question.
First, you will have to try to use insulation to reduce noise transfer by deflecting or absorbing the sound waves, much in the same way air is trapped by the insulation. Batt insulation, whether fibreglass or mineral fibre, is usually the most costeffective type for this purpose, but may not be the most practical in your situation.
If you fill the entire cavities between the floor joists with these batts, there will be a considerable amount of air space in this material to prevent much of the sound transfer from items like voices or electronic equipment. Unfortunately, this may require considerable work in removing the entire ceiling on the main floor, which may not be fully necessary.
The other item to consider is noise transfer through vibration or solid material. This is likely the cause of most of the complaints from the tenants in the lower suite. The comment about footsteps being heard is due to vibration or floor movement in the joists or other components of the floor above. Since there is continuous solid material between the top of the hardwood floor through to the drywall below, sounds may transfer through this area between the suites. Insulating between the joists may do little to prevent that type of sound transfer.
Because of the previous concern, there may be an easier way to stop the sound transfer between different floors without removing all the ceilings. If you have sufficient height between the floor and ceiling on the main level of your triplex, you may be able to drop the existing ceiling and install soundproofing material without disturbing the old ceilings. This may be accomplished with metal T-bar ceilings, common in basements and commercial buildings.
This type of ceiling is normally installed several centimetres below the joists above, which will allow for installation of continuous batt insulation without direct ceiling connection to the floor system above. Also, acoustical ceiling tiles may be purchased that are designed to further deaden the sound above and below this area.
If there is not sufficient height to install a drop ceiling, securing a thin layer of rigid insulation over the existing drywall, followed by a new layer of drywall, may be considerably easier than doing it your suggested way. This will also bridge the entire floor system, including the bottom of the joists, preventing some vibration noise as well as that transferring through the hollow floor system. This will only require a loss of a few centimetres of ceiling height.
Finally, there may be an even easier way to approach this concern, but you may not be able to accomplish this yourself. There are companies that install specialized coatings to ceilings and walls, usually sprayed on, that help improve the acoustical resistance of these areas. While mostly used in commercial or industrial buildings, these coatings may be a quick way to achieve your goal.
If your tenants are only experiencing mild disturbances, it may be excessive to removal all the ceiling sheathing just to gain a bit of an improvement in solitude. Check the local listings and Internet for contractors in your area that may be able to spray away your noise problems, without the need for major renovations.