Which houses are likely to have it
Health Canada sets out three bands. Homes built before 1960 probably contain lead-based paint. Homes built between 1960 and 1990 may have lead paint on exteriors and smaller amounts on some interior surfaces. Homes built after 1990 should not contain lead, because consumer paints produced in Canada and the United States were virtually lead-free by that point.
In Ottawa terms, that puts most of the Glebe, Old Ottawa South, Ottawa East, Sandy Hill, Lowertown, Hintonburg, Mechanicsville, Westboro's older streets and the pre-war parts of New Edinburgh squarely in the first band. Much of Alta Vista, Elmvale, Carlington and the 1950s and 1960s parts of Nepean fall into the second. Barrhaven, Kanata Lakes, Stittsville and Avalon are overwhelmingly in the third.
The band is a guide rather than a test. A 1955 bungalow that was gutted in 2004 may have nothing left to worry about, and a 1975 house may have an original oil-based exterior trim coat that does. If it matters, a sample can be tested, and there are swab kits for a first indication.
What Health Canada actually says to do
The headline advice is that undisturbed lead paint in good condition is usually best left alone. Health Canada's guidance is that if lead-based paint is in good condition and not within reach of children, it is best to leave it alone, paint over it, or cover it with wallpaper, wallboard or panelling.
Where paint has to come off, the method is the point. Health Canada's wording is direct: do not use sanders, heat guns or blowlamps to remove paint in older homes, because this can create dust and fumes that contain lead. Its alternative is a chemical paint stripper, ideally a paste applied with a brush, used with goggles, gloves and a good-quality breathing mask, keeping children and pregnant women away from the work area.
That guidance is written for a homeowner doing the work. A contractor doing it commercially is additionally working under Ontario's occupational health and safety requirements for lead, which govern containment, respiratory protection and cleanup on a construction project.
How it changes a painting quote
It changes the method, the schedule and the price. Lead-safe preparation means sealing the work area with plastic, covering floors, wet-scraping or chemically stripping rather than dry-sanding, using a vacuum with a high-efficiency filter rather than a broom, and bagging the waste. Windows and doors are the worst of it, because friction surfaces generate dust every time they are opened.
The effect on cost is per opening rather than per square metre. Stripping and repainting a set of original double-hung wood windows in a pre-war Glebe house can cost several hundred dollars each and take a day apiece. A quote that treats them as trim linear metres has not understood the job.
The honest alternative is often encapsulation: leave the sound coating where it is, wash it, spot-prime any failed areas without aggressive sanding, and coat over it. That is cheaper, faster and, where the existing paint is sound, is what Health Canada's own advice points toward.
Questions to put to a contractor
Do you know the age of this house, and does it change your method. What is your approach to the trim: strip, or scuff and coat. If you are stripping, chemical or mechanical, and if mechanical, what dust control. Are you using a vacuum with a high-efficiency filter. How are you containing and cleaning the work area each day. Where does the waste go.
If the answers are vague, or if the plan involves a belt sander and an open window, keep looking. There is no lead certification requirement for painters in Ontario, and there is no painter's licence at all, so the contractor's method is the only thing standing between your household and the dust.
One last practical point. If you have young children or someone in the household is pregnant, the conservative choice is to postpone any disturbance of pre-1960 paint until they can be out of the house for the duration and the cleanup, rather than to manage it around them.