Built to spec
Built to your engineered drawings, survey, and the real site conditions, not a one-size-fits-all approach forced to fit.
Commercial & Heavy-Civil Construction
Mould Remediation
Harrowgate performs moisture-source correction, containment, selective removal, cleaning, drying, and reinstatement for mould-affected commercial and industrial properties across the GTA and Ontario.
- Licensed, Insured & WSIB-Covered
- 20 Years in Business
Get a Quote
Tell us what you need and we’ll get you a quote. Licensed, insured & WSIB-covered · Free, no-obligation quote & on-site assessment.
Get a Quote
Licensed, insured & WSIB-covered · Free, no-obligation quote & on-site assessment.
20 Years in Business
Licensed, Insured & WSIB-Covered Completed to code & Ontario requirements Completed on site and built to the drawings Performed & installed on site across Ontario
Why Harrowgate Group
What to expect from mould remediation
Made to last
Durable materials and methods chosen for the load, traffic, and environment on site.
Quote-ready
Send specs, drawings, or photos and get a free, no-obligation site visit and estimate with no guesswork.
Code-conscious
Installation and site work completed in accordance with Ontario requirements.
Our Process
How we plan and deliver mould remediation
Commercial mould remediation removes contaminated porous materials, cleans salvageable assemblies, controls airborne spread, and corrects the moisture condition that caused growth. Harrowgate performs the work across the GTA using scoped containment, negative air, HEPA cleaning, controlled demolition, drying, verification, and durable building repairs suited to occupied and operating facilities.
- 01 Send your inquiry, a few photos or a description of the site.
- 02 We come out, assess the site, take measurements, and confirm the scope.
- 03 We complete the mould remediation on site, to the load and finish the job needs.
- 04 We install it, finish to grade, and clean up, one accountable crew, start to finish.
Local Context
A closer look at mould remediation
Scope
Understanding mould remediation
Which mould remediation method fits the condition?
Small localized growth on cleanable non-porous material can sometimes be addressed with controlled cleaning after the moisture source is corrected. Porous gypsum, insulation, ceiling tile, and heavily colonized materials generally require controlled removal. Semi-porous wood and concrete are assessed for surface cleaning, abrasion, or removal from condition and depth. Containment, negative air, HEPA filtration, dust suppression, and personal protection scale with affected area, occupancy, HVAC interaction, and the accepted remediation plan.
How we remediate mould-contaminated buildings
Step 1, We start with moisture mapping and a source investigation, not indiscriminate sampling. Infrared scanning, pin and pinless moisture meters, borescope inspection, drawings, roof or wall review, and selective openings establish the wet boundary and likely path. The remediation limit includes visible growth, water-damaged porous material, and concealed cavities affected by the same event. Clean reference areas and material moisture targets are recorded.
Step 2, Containment is sized to the contamination and occupancy risk. Critical barriers isolate openings, return-air paths, ceiling plenums, and penetrations. HEPA-filtered negative-air machines maintain inward airflow, while pressure and filter condition are checked during work. A clean entry, worker decontamination sequence, and sealed waste route prevent contaminated dust from crossing into occupied or previously cleaned spaces.
Step 3, Porous materials such as gypsum board, ceiling tile, insulation, and badly deteriorated wood products are cut out beyond the affected edge and bagged at the point of removal. Semi-porous framing is wire-brushed, scraped, sanded, or media-cleaned only where the substrate can be restored without damaging structure. Non-porous metal, concrete, and durable finishes are HEPA vacuumed and damp cleaned with a compatible agent.
Step 4, Drying follows removal. Air movers and dehumidifiers are arranged to draw moisture out without pushing contamination beyond control. Cavities remain open until moisture readings are stable and the source repair has been tested. Final cleaning proceeds high to low, followed by visual inspection and any consultant-directed verification. Reinstatement uses assemblies that restore fire, acoustic, vapour, air, and drainage functions.
Step 5, Harrowgate closes the affected zone after removal, retained-surface cleaning, drying, source correction, waste removal, final housekeeping, and the specified post-remediation verification support reconstruction.
Which materials and Ontario standards apply?
Mould remediation follows the accepted assessment and remediation plan, Ontario occupational health duties, building and facility procedures, manufacturer limits, and applicable local municipal requirements. Ontario guidance emphasizes correcting moisture, cleaning, remediating contaminated material, inspection, and preventive maintenance.
Work-area controls are selected from contamination extent, occupancy, material, HVAC connection, access, and disturbance method. Respiratory and personal protection, containment, pressure, HEPA filtration, decontamination, cleaning, and waste movement follow the risk assessment and accepted industry practice.
Products are used only after physical removal and cleaning requirements are satisfied. Biocides, encapsulants, coatings, and cleaners must suit the substrate and occupancy and cannot substitute for removing unsalvageable porous material or correcting the water source.
Post-remediation verification is defined before work. It can include dry materials, visually clean surfaces, corrected moisture source, completed removal limits, acceptable dust condition, consultant inspection, and testing where specified. Reconstruction proceeds after the accepted release.
Planning mould remediation? Talk it through with our team.
What goes wrong, and how we prevent it
The common failure is treating stain while leaving the moisture source active. We trace water uphill and upstream, inspect connected cavities, and verify repairs under realistic conditions. A roof patch, pipe repair, drain correction, or insulation change is completed before close-in. Moisture readings are logged until the assembly reaches the agreed dry condition.
Uncontrolled demolition aerosolizes spores and fragments through corridors and HVAC systems. We establish containment and pressure before opening affected assemblies, isolate mechanical returns, bag waste inside the controlled zone, and use HEPA-equipped tools. The enclosure is extended when inspection shows growth beyond the original boundary.
Overuse of coatings can conceal remaining contamination or trap moisture. Encapsulants are not a substitute for removal and cleaning. They are used only when the substrate is sound, dry, visibly clean, and the specification calls for a compatible coating. Final inspection focuses on every cavity, fastener line, sill, deck flute, and service penetration before reconstruction.
Have drawings for mould remediation? Send them over and we will scope it.
FAQ
Mould Remediation FAQ
What causes mould in commercial buildings?
Mould growth requires persistent moisture. Commercial causes include roof leaks, failed wall joints, plumbing releases, wet insulation, foundation seepage, blocked drains, cold-surface condensation, uncontrolled humidity, and incomplete drying after a flood. Harrowgate locates the water path and affected assembly so remediation corrects the cause rather than only cleaning visible growth.
Does all mouldy material have to be removed?
No. Porous materials that cannot be fully cleaned, such as contaminated gypsum board, ceiling tile, and insulation, are normally removed. Sound structural wood, concrete, metal, and other durable surfaces can often be retained after mechanical cleaning, HEPA vacuuming, damp wiping, and drying. The project protocol and substrate condition determine the decision.
How do you prevent mould from spreading during demolition?
We isolate the work with sealed barriers, protect HVAC openings, maintain inward airflow with HEPA-filtered negative-air units, and establish controlled entry and waste routes. Materials are cut carefully and bagged inside containment. HEPA-equipped tools, progressive cleaning, pressure checks, and final high-to-low cleaning keep contaminated dust inside the defined work zone.
Is air sampling always required for mould remediation?
Not always. Visible growth and water-damaged materials can often be scoped through inspection, moisture mapping, and selective openings. An occupational hygienist may specify air or surface sampling for complex, disputed, sensitive, or clearance-driven projects. Harrowgate follows the project protocol and keeps physical source removal, drying, and visual cleanliness as the core controls.
How dry must the area be before rebuilding?
Acceptance depends on the material and a dry reference from an unaffected part of the same building. We record moisture readings over time and verify that the source repair is effective. Cavities are not closed while readings remain elevated, insulation is wet, or condensation conditions persist. Stable dry readings support the close-in decision.
Can mould remediation happen while a facility stays open?
Yes, when the contamination, access, and mechanical systems permit safe phasing. We use sealed work zones, negative air, protected access routes, scheduled noisy work, and defined handback points. The facility team coordinates occupant movement and HVAC operation while Harrowgate controls demolition, waste movement, cleaning, drying, and reconstruction within each phase.
What should a mould remediation closeout include?
Closeout should document the repaired moisture source, removed materials, cleaning method, drying readings, visual acceptance, consultant verification where specified, and reconstructed assemblies. Harrowgate also records concealed conditions and recommends access or maintenance measures for roofs, drains, sealants, plumbing, and humidity controls that could affect future building performance.
Must every mould-affected material be removed?
No. Non-porous and some semi-porous materials may be cleanable when their condition and the remediation plan support it. Heavily contaminated or water-damaged porous materials often require controlled removal because growth and residue can extend below the surface.
Why is fixing the moisture source part of remediation?
Mould growth depends on moisture. If leakage, condensation, humidity, flooding, or drainage remains uncontrolled, cleaned or replaced materials can become wet and support new growth. Source correction and drying protect the remediation result.
Still have a question about mould remediation? Ask our team directly.
Our Work
View Our Projects See real projects across Toronto & Ontario
Commercial and heavy-civil construction delivered for developers, contractors, property managers, and municipalities.
Get a quote for mould remediation
Send drawings, a site plan, or a description of the scope. Harrowgate Group is licensed, insured, and WSIB-covered.
Licensed, Insured & WSIB-Covered, work managed and documented on every job
Send your project details
Tell us what you need and we’ll get you a quote. Licensed, insured & WSIB-covered · Free, no-obligation quote & on-site assessment.
Mould Remediation Across the GTA
View all service areas →Harrowgate Group provides mould remediation, delivered and installed with quote-ready support across Toronto and surrounding Ontario communities.
