Who Needs a Designated Substances Survey?

A project can appear straightforward until crews open a ceiling, remove floor finishes, or access a mechanical room that has not been renovated in decades. That is when the question of who needs a designated substances survey becomes operationally significant. For Ontario construction projects, the answer typically begins with the building owner or party acting as the owner under the Occupational Health and Safety Act.

A designated substances survey, often called a DSS, identifies hazardous materials that may be encountered during construction work. It gives project teams the information needed to plan safe work, price the work accurately, and meet their regulatory responsibilities before labor begins. It is not simply a preconstruction formality. It is a risk-management document that can affect schedule, procurement, worker protection, and liability.

Who needs a designated substances survey before construction?

In Ontario, an owner must determine whether designated substances are present at a project site before construction begins. If they are, the owner must prepare a list of those substances and provide it to prospective contractors as part of the tendering process, then to the constructor before work starts.

The obligation applies broadly. Commercial property owners, landlords, developers, municipalities, school boards, hospitals, manufacturers, and institutional facility operators may all require a DSS when they are planning work that could disturb existing building materials, equipment, or site conditions. The legal definition of an owner can also extend beyond the registered property owner. A tenant, project manager, or other party with control of the workplace may assume owner responsibilities depending on the project arrangement.

The constructor and contractors also need the information, but their role is different. They rely on the owner-provided survey to establish safe methods, select qualified subcontractors, train workers, obtain appropriate controls, and avoid making assumptions about concealed materials. A contractor should not be expected to discover unknown designated substances after mobilization without a corresponding impact on scope, cost, and schedule.

Projects that commonly require a DSS

A survey is generally warranted whenever planned construction work could expose workers to hazardous materials. Common examples include:

• Interior renovations involving ceilings, walls, flooring, insulation, piping, or mechanical systems

• Demolition, selective demolition, and building decommissioning

• Repairs or replacements to roofs, boilers, elevators, electrical systems, and HVAC equipment

• Tenant improvements, fit-outs, and leasehold reinstatement work

• Infrastructure upgrades in older facilities, including hospitals, schools, industrial plants, and municipal buildings

• Emergency repairs where damaged materials may contain asbestos, lead, or other regulated substances

Age alone does not determine whether a building contains designated substances. Older buildings often require more extensive investigation because hazardous materials were historically used in many common applications. However, newer facilities can also contain substances or equipment requiring assessment. The scope should be based on the planned work and the materials likely to be disturbed, not on a broad assumption that one building era is risk-free.

What are designated substances?

Ontario regulations identify 11 designated substances: acrylonitrile, arsenic, asbestos, benzene, coke oven emissions, ethylene oxide, isocyanates, lead, mercury, silica, and vinyl chloride. In the built environment, asbestos, lead, mercury, silica, and certain isocyanate-containing products are frequently relevant to construction planning.

The presence of a substance does not automatically prevent work from proceeding. The practical issue is whether the work could disturb it and create an exposure risk. For example, asbestos-containing drywall joint compound may be manageable during routine occupancy but requires defined controls when a wall is demolished. Likewise, lead-containing coatings can become a significant concern during abrasive preparation, cutting, or demolition.

A competent survey identifies known or suspected locations, documents sampling and laboratory findings where appropriate, and describes the material condition. That information allows the project team to determine whether removal, enclosure, controlled work procedures, or additional investigation is necessary.

A DSS is not the same as an asbestos survey

Asbestos is often the primary concern in older properties, and an asbestos survey may be an essential part of due diligence. It is not always enough to meet the broader purpose of a designated substances survey.

A properly scoped DSS considers the range of designated substances relevant to the project. Depending on the facility and scope of work, this can include lead coatings, mercury-containing equipment, silica-generating materials, chemical residues, or other hazards. An industrial facility may also require a more detailed review of process areas, equipment history, and maintenance records than a conventional office renovation.

The distinction matters because incomplete information can create false confidence. If a survey addresses only asbestos while planned work involves removing old lighting components, coatings, pipe insulation, or process equipment, important hazards may remain unidentified. A multidisciplinary assessment approach helps align the investigation with the actual construction scope.

When should the survey be completed?

The DSS should be completed early enough to inform design, tender documents, and contractor pricing. Waiting until a contractor has started demolition is one of the most common and costly mistakes. At that stage, discovery of hazardous material can stop work, require urgent sampling, force a scope change, and create disagreement over responsibility for delays.

Early assessment provides better options. If hazardous materials are identified during planning, the owner can incorporate abatement into the project sequence, define responsibilities clearly, budget for removal or controls, and coordinate access requirements. In some cases, a survey may reveal that a less invasive design approach avoids disturbance altogether.

There are situations where full access is not available before tender. A building may be occupied, equipment may be operating, or concealed spaces may be inaccessible without destructive investigation. In those cases, the survey should clearly state its limitations, identify suspect materials, and recommend reasonable allowances or follow-up investigation. A limited survey is not necessarily inadequate, but its constraints must be transparent and managed in the project documents.

What a useful designated substances survey should provide

A DSS should be practical for the people who must act on it. A report that lists laboratory results without connecting them to locations, work activities, or control requirements may satisfy little more than recordkeeping needs.

For effective project delivery, the survey should define the areas inspected, describe inaccessible locations, identify confirmed and suspected designated substances, and provide drawings, photographs, or location references where useful. It should also distinguish between materials that will be disturbed by the planned work and materials outside the project area.

Recommendations should be proportionate to the risk. Some materials require removal before construction; others can remain in place if protected and not disturbed. Where further testing is needed, the report should identify when it must occur and how results will be communicated to the constructor. Clear documentation supports safer decisions without creating unnecessary project scope.

Responsibilities do not end when the report is issued

A DSS is a starting point for coordinated hazard management, not a substitute for contractor planning. Owners should provide the report to bidders and the constructor, respond promptly to questions, and ensure that changes to the project scope are reviewed for new exposure risks. If work expands into unassessed areas, the survey may need to be updated before those areas are disturbed.

Constructors and employers remain responsible for implementing appropriate site controls, including worker training, protective measures, exposure control plans, and compliance with applicable regulations. They should also stop and reassess work if unexpected materials are discovered. A report prepared months earlier cannot account for every concealed condition uncovered during demolition.

For large or complex projects, the strongest results come from integrating the DSS with design coordination, demolition planning, environmental consulting, and construction management. This is particularly valuable in occupied buildings, healthcare settings, industrial operations, and public facilities where safety controls must be balanced with continuity of operations.

Martech Group approaches designated substances assessments as part of a broader project-risk strategy, combining hazardous materials expertise with practical knowledge of building systems, construction sequencing, and compliance requirements.

The most effective time to address designated substances is before the project team has committed to a schedule, a fixed price, or a demolition plan. A well-scoped survey gives owners and contractors a clear basis for making informed decisions when changes are still manageable.