Secondary Dwellings - Grading, Servicing and Surveys

Laneway suites, also known as garden suites or auxiliary dwelling units (ADUs), are self-contained residential units located on the same lot as a primary dwelling. These units are gaining popularity in cities such as Hamilton, Burlington, Toronto, and Cambridge as homeowners look for creative ways to increase property value, provide additional housing options, and accommodate multigenerational living. While the terms laneway suites, garden suites, and ADUs are often used interchangeably, they all refer to the same concept: a secondary dwelling unit on a single residential lot.

Modern style secondary dwelling designed for family.

Benefits of Laneway Suites

Laneway suites offer numerous advantages to homeowners and the community at large. They provide an opportunity to generate rental income, helping to offset mortgage costs. For families, they can serve as a private space for aging parents or adult children, fostering close-knit, multigenerational living while maintaining independence. Additionally, these units contribute to the housing supply in urban areas where space is at a premium, supporting affordable housing initiatives and densification goals.

From an efficiency and environmental perspective, laneway suites make use of existing land and municipal services, reducing the need for sprawling development. For example, adding a laneway suite requires no additional municipal sewers, watermains, roads, hydro, etc. to be constructed.

Challenges and Feasibility

Despite their benefits, laneway suites are not feasible in all areas. Several challenges must be addressed before adding one to a property. From the field of civil engineering, key considerations include grading, water, and sanitary servicing.

Grading Challenges

A proper grading plan is essential to ensure the site can be adequately drained without impacting neighboring properties. If a lot is poorly drained or if existing runoff flows toward a neighboring lot, significant modifications may be required, or a sub-surface pit added to help infiltrate stormwater. For instance, driveways may need to be narrowed to create a side yard swale, or a shallow channel that directs stormwater toward the street. Without these measures, water could pool on-site or cause flooding issues for neighboring properties, leading to disputes and potential legal challenges.

To develop a grading plan, a topographic survey is needed to map the existing ground elevations accurately. This survey identifies any low-lying areas and determines the flow of water across the property. An experienced engineer, such as one from Everwest Engineering, can perform this survey and design a grading plan that meets municipal requirements and protects adjacent properties.

ADU designed for rental.

Water Servicing

Connecting water to a laneway suite requires careful planning and adherence to the Ontario Building Code. The water supply for the suite must connect immediately downstream of the primary house’s water meter. Shut-off valves are required in both the main house and the laneway suite to allow independent control of water flow. This setup ensures that water servicing for the laneway suite does not interfere with the main house’s system.

Sanitary Servicing

The laneway suite’s sewer line can connect to the main building sewer, provided this connection includes a cleanout for easy maintenance and inspection. A backflow preventer is also required in both the laneway suite and the main building to prevent sewage from backing up into either dwelling. These precautions are especially critical in areas prone to heavy rainfall or where municipal sewer systems are at capacity.

Auxiliary dwelling unit (ADU) design for rental.

Regulatory Considerations

Municipalities in the Greater Toronto and Hamilton Area have been adapting zoning bylaws to facilitate the construction of laneway suites, but specific requirements vary. Homeowners must ensure their property meets all zoning regulations, including minimum lot size, setbacks, and access requirements. Additionally, permits for construction, grading, and servicing must be obtained before starting work.

Planning and Design

Designing and building a laneway suite requires collaboration between homeowners, architects, and engineers. The first step is to assess the property’s suitability through a site analysis. Once feasibility is confirmed, the design phase can begin, focusing on functionality, aesthetics, and compliance with local bylaws and the Ontario Building Code.

Working with an experienced engineering firm can streamline this process. Engineers can handle critical tasks such as preparing the grading plan, designing water and sanitary connections, and ensuring compliance with stormwater management regulations. Their expertise minimizes the risk of costly mistakes and ensures a smoother approval process.

Conclusion

Laneway suites, garden suites, or ADUs are a valuable addition to residential properties, offering financial, social, and environmental benefits. However, their successful implementation requires careful planning to address challenges such as grading and servicing. With the help of skilled professionals, homeowners can navigate these challenges and unlock the potential of their property. For those considering a laneway suite in Hamilton, Burlington, Toronto, or Cambridge, Everwest Engineering can provide the expertise needed to bring your vision to life.