Mold remediation in Ottawa costs roughly $600 to $1,800 for a small, contained patch under about 30 square feet, and $2,500 to $8,000 for a typical mid-sized job such as one wall of a finished basement or a bathroom behind the tile. Large or whole-basement remediation involving containment, HEPA filtration, and significant demolition commonly runs $8,000 to $25,000 in 2026, and severe cases with structural rot can exceed that. Priced by area, most Ottawa remediation firms land between $20 and $45 per square foot of affected surface once containment, removal, disposal, HEPA cleaning, and antimi...
Remediation companies scale pricing by the size of the contaminated area and how much containment the job demands. A small job — under roughly 30 square feet, such as mould on a section of drywall behind a leaking washing machine — typically runs $600–$1,800 and can often be completed in a single day. A medium job of 30–100 square feet, like a bathroom wall cavity or a strip of finished basement wall, generally costs $2,500–$8,000 because it requires poly containment, negative air machines, HEPA...
If mould follows a burst pipe or sewer backup, water extraction and drying come first and are billed separately, usually $1,200–$4,000 for a basement. After-hours or weekend emergency callouts typically carry a 1.5x labour multiplier.
A legitimate Ottawa remediation quote is not just "spray and wipe." It should itemize containment (poly barriers and zippered access), negative air pressure with HEPA-filtered air scrubbers, removal and bagged disposal of porous materials like drywall, insulation, carpet, and underlay, HEPA vacuuming of all surfaces, damp-wiping with an antimicrobial, and controlled drying. Non-porous materials such as concrete, framing lumber, and steel can usually be cleaned and treated rather than removed. En...
A visual mould inspection from an independent Ottawa building science or indoor air quality consultant typically costs $300–$600. Adding air sampling with lab analysis runs $150–$300 per sample, so a typical inspection with two indoor samples and one outdoor control comes to $600–$1,200 all in. Surface tape-lift or swab samples are cheaper at roughly $75–$150 each. Health Canada's guidance is that visible mould should be removed regardless of species, so testing is not always necessary for a sma...
For larger jobs, budget $400–$800 for independent clearance testing after the work is done. It confirms spore counts are back to normal and gives you documentation for insurance or a future home sale.
Ottawa's climate creates a near-perfect mould environment twice a year. Spring meltwater saturates clay soils around foundations, and homes with poor lot grading, disconnected downspouts, or clogged weeping tile take on moisture in the basement. Then in July and August, warm humid air enters cool basements and crawl spaces and condenses on cold surfaces. Add the winter side: interior humidity from cooking, showers, and drying clothes migrates into attics through poorly sealed ceiling penetration...
Sometimes, and the distinction matters. Most Ontario home insurance policies cover mould damage when it results from a sudden and accidental covered event — a burst pipe, an appliance supply line failure, or water damage from putting out a fire. What is almost never covered is mould caused by gradual seepage, long-term humidity, poor maintenance, or groundwater intrusion, and many policies explicitly exclude flooding unless you carry an overland water or sewer backup endorsement. Coverage limits...
Mould remediation is not a licensed trade in Ontario, which means anyone can advertise the service — so vetting is entirely on you. Look for technicians certified through IICRC (Institute of Inspection, Cleaning and Restoration Certification), particularly the Applied Microbial Remediation Technician designation, and confirm the company carries general liability insurance and WSIB coverage. Ask them to show you their containment and negative air setup plan in writing, and ask what happens if the...
In 2026, small contained jobs under about 30 square feet run $600–$1,800, mid-sized jobs of 30–100 square feet run $2,500–$8,000, and large or whole-basement remediation runs $8,000–$25,000. Priced by area, most Ottawa firms charge roughly $20–$45 per square foot of affected surface including containment, removal, HEPA cleaning, and disposal.
A visual inspection from an independent consultant runs $300–$600. Adding air sampling with lab analysis costs $150–$300 per sample, so a typical inspection with two indoor samples and an outdoor control totals $600–$1,200. Use a different company for testing than the one performing removal to avoid a conflict of interest.
Usually only when the mould results from a sudden, accidental covered event such as a burst pipe. Mould from gradual seepage, chronic humidity, groundwater, or poor maintenance is typically excluded, and even covered claims are often capped at $10,000–$25,000. Overland water and sewer backup endorsements matter, so check your policy before assuming coverage.
Attic mould treatment generally runs $2,500–$7,500 depending on the sheathing area affected. Budget another $600–$1,500 to correct the cause, which in Ottawa homes is usually bathroom fans venting into the attic or blocked soffit ventilation. Without fixing the ventilation, the mould comes back.
Health Canada guidance suggests small areas — roughly under one square metre of hard, non-porous surface — can often be cleaned by a homeowner with soap and water and proper protective equipment. Larger areas, anything inside wall cavities or insulation, and any situation involving sewage or a household member with respiratory issues should go to a certified professional with proper containment.