Acoustical considerations when building on less-than-ideal urban plots

By Nicholas Sylvestre-Williams, P.Eng.

Photos ©
Photos ©

For years, many in the construction industry have complained about the shortage of buildable land in major cities such as Toronto. From an urban planner’s perspective, good land means it is well set back from industrial areas and noisy transportation sources. For example, parking lots situated in the city’s core were easily converted to condos. They were ideal sites because of their proximity to other residential buildings or quieter commercial or office facilities. However, these good plots of land are becoming scarce. Therefore, developers need to expand their search.

In many cases, what remains of urban land is less than ideal for construction and has typically been difficult to obtain permits for because they are close to railway lines, highways, airports, or encroaching on existing, established industry. This type of land presents new construction challenges, including keeping the noise and vibration at bay.

For years, there was a prevalent belief distance is the only tool to deal with noise issues. A lack of land affordability and availability in the city core was one of the many causes of urban sprawl, as suburbs rapidly grew to accommodate the increasingly large population. However, many are opting to stay in urban areas for a shorter commute to work or to minimize their carbon footprint.

Regardless of the reason, demand continues to exceed supply. A 2019 report by the Royal Bank of Canada (RBC) found Toronto would need to double the amount of condo and apartment construction to meet future demand. So, it is no surprise an increasing number of developers are looking to build on less-than-ideal plots of land.

A careful look at the project's acoustic challenges is a worthy exercise prior to kick-starting developments on less-than-ideal sites such as ones near rail lines.
A careful look at the project’s acoustic challenges is a worthy exercise prior to kick-starting developments on less-than-ideal sites such as ones near rail lines.

The questions are how to build in the margins, and how to ensure acoustic comfort for those who will be living or working in buildings close to sources of noise and vibration? Also, how to make it affordable so a mid-rise building can be viable.

Understanding regulations

Before delving into acoustical considerations in construction, it is very important to understand the regulations. The province of Ontario is heavily invested in protecting its infrastructure, to the point where the Provincial Policy Statement (PPS) says in Section, “Planning for land uses in the vicinity of airports, rail facilities, and marine facilities shall be undertaken so that a) their long-term operation and economic role is protected; and b) airports, rail facilities, and marine facilities, and sensitive land uses are appropriately designed, buffered, and/or separated from each other […].” This means when a development is proposed, the existing airport or rail facility’s use must be considered first and foremost, and a developer cannot simply build closer without ample demonstration of compatibility and suitability.

Due to the PPS, most Ontario municipalities have a robust acoustic criterion to meet, both for outdoor noise levels at people’s windows and at outdoor locations. There are also indoor sound levels to be met from road, rail, and aircraft noise. As such, when considering constructing on lands near noisy sources (i.e. industries, road, rail, or aircraft), the design freedom will be impacted. This means one may need to reorient the building’s design to ensure noise levels are met or introduce premium architectural elements. These sites are not suited for a cookie-cutter approach. Rather, a unique view needs to be taken to address the site’s specific needs.

The technical details on the limits are quite involved, but as an example, noise from an airport such as the Toronto Pearson International Airport, is presented in the form of a noise exposure forecast (NEF). The forecast is shown on a map and gives the developer an idea of the expected noise level if they were to build in an area. Transport Canada advises an NEF level greater than 30 is likely to produce some amount of annoyance and that above 35, complaints will surely be numerous. As such, the PPS prohibits new residential development near airports with an NEF above 30. Despite this provincial limitation, there are developments of sensitive land uses that have occurred in areas exceeding NEF 30, with appropriate acoustic insulation features incorporated in the building.

Another example of the challenge of constructing near noisy infrastructure is near busy highways. Road noise has a different set of limits that need to be met, and they vary based on time of day and location. For example, the daytime limits are met outdoor and the nighttime limits indoors. Note, there are outdoor limits for nighttime as well but they are not the restricting factor because if the outdoor daytime limits are met, the nighttime limits will be satisfied as well.

Also, nighttime indoor limits themselves vary depending on the space (i.e. 40 dBA bedrooms and 45 dBA for living rooms) and these all need to be assessed and demonstrated to comply with the municipality’s requirements.

It is important to keep in mind, the guidelines set out by the municipality are not strict. The limits do not mean they will not be a problem, only that they will minimize complaints. Bodies like the Canadian National Railway (CNR) or the Toronto Transit Commission (TTC) do not want to rely on minimum standards, they want to ensure the developer’s do everything they can so they will sometimes ask for more than just what the minimum standards are. When the neighbours are the CNR or the TTC, one may need their buy-in when it comes to concessions. When considering constructing near one of these authorities’ lands, in the zoning, planning, and approval process, these authorities have the right to object if they feel the development will cause problems once residents move into the buildings. The authorities also have significant resources and experts who will dive deeply into the technical studies and require justification until they are satisfied the development does not pose any risk to them.

Control the content you see on! Learn More.
Leave a Comment


Your email address will not be published. Required fields are marked *