Question 1

When is a Designated Substance Survey required in Thornhill?

Accepted Answer

Under Ontario's Occupational Health and Safety Act (OHSA), a Designated Substance Survey is legally required before any construction project — including renovation, alteration, demolition, or repair work — that may disturb designated substances in a Thornhill building. This obligation applies to all building types: commercial, industrial, institutional, and residential where workers are involved. A property owner who hires workers to renovate a pre-1990 Thornhill building without first conducting a DSS is in direct violation of OHSA obligations. The requirement applies regardless of project size — even replacing drywall or stripping floors in an older building triggers the DSS requirement if designated substances may be present.

Question 2

What substances are covered in a DSS?

Accepted Answer

Ontario's OHSA designates 11 substances that require specific controls when workers may be exposed: asbestos, lead, mercury, silica, acrylonitrile, arsenic, benzene, coke oven emissions, isocyanates, designated biological agents, and vinyl chloride. In Thornhill pre-1990 buildings, the most commonly found designated substances are asbestos (in multiple material types), lead (in paint and plumbing), mercury (in thermostats, switches, and fluorescent lighting ballasts), and silica (in concrete, masonry, and tile). Our survey assesses all 11 substances systematically, with sampling protocols appropriate to each material type, and delivers a single O.Reg 278/05-compliant report covering the complete scope.

Question 3

Who needs a Designated Substance Survey?

Accepted Answer

Under Ontario's OHSA, the obligation to conduct a DSS before construction or renovation work in Thornhill falls on the constructor (general contractor) and the owner of the property, both of whom have independent legal obligations. Project managers, renovation companies, and subcontractors all share exposure if a DSS was not conducted before work begins. Owner-operators of commercial, industrial, and institutional buildings have the broadest obligations and are most frequently the subject of Ministry of Labour inspections and enforcement. Residential property owners hiring workers for significant renovations of pre-1990 Thornhill homes are also subject to OHSA obligations as workplace owners.

Question 4

How much does a Designated Substance Survey cost in Thornhill?

Accepted Answer

Designated Substance Survey pricing in Thornhill starts from $399 for a standard residential property with a defined renovation scope. Small commercial or light industrial units under 5,000 sq ft typically run $600–$900. Larger commercial, multi-unit residential, or institutional buildings requiring comprehensive multi-area sampling and the full 11-substance assessment are quoted individually based on building size, age, and renovation scope. All DSS pricing includes on-site inspection, systematic sampling under proper containment, accredited laboratory analysis, and a full written O.Reg 278/05-compliant report. Contact ASADS at (647) 801-9311 for a custom quote specific to your Thornhill property.

Question 5

How long does a DSS take?

Accepted Answer

The on-site inspection and systematic sampling phase of a Designated Substance Survey in Thornhill typically takes 2–4 hours for a standard residential or small commercial building, depending on size, number of rooms, and renovation scope. Larger commercial or industrial facilities may require 4–8 hours or multiple site visits. All samples are submitted to an accredited laboratory immediately following the site visit. Standard PLM and metals analysis results are returned within 3–5 business days. Rush 24-hour laboratory processing is available for time-sensitive construction schedules or transaction deadlines — contact us when booking to arrange expedited turnaround for your Thornhill project.

Designated Substance Survey Thornhill | O.Reg 278/05 | ASADS