Pyrite Removal and Replacement
Experts in treating pyrite-contaminated soils according to CTQ-M200 protocol
Pyrite is an iron sulfide mineral naturally present in certain backfills under concrete slabs. In the presence of moisture and oxygen, it oxidizes and produces a white powder that swells, which can lift the concrete slab and crack foundations and partitions.
Archi-Maitre Excavation specializes in the identification, excavation and replacement of pyrite-contaminated backfills. No chemical solution can neutralize oxidation: the only way to eliminate pyrite is to completely remove the affected backfill and replace it with sound material.
Context: The Pyrite Crisis in Quebec
This phenomenon, well known in Quebec, caused a major housing crisis around the year 2000, particularly in Montérégie (south of Montreal). Pyrite-related problems have since been identified in dozens of municipalities in the greater Montreal area.
The highest risk areas include:
- •South Shore: Châteauguay, Brossard, Longueuil, Boucherville, Saint-Bruno, Saint-Hubert, Varennes
- •Montreal Island: Rivière-des-Prairies, Pointe-aux-Trembles
- •North Shore: Repentigny, Terrebonne
- •West Island: Lachine, Dorval, Dollard-des-Ormeaux, Pointe-Claire, Kirkland, Pierrefonds, Beaconsfield
If your property is located in these regions or shows suspicious symptoms, it is crucial to have it checked for pyrite.
CTQ-M200 Protocol: The Recognized Standard
Our pyrite treatment services follow the CTQ-M200 protocol, which is the methodology recognized by competent authorities for analyzing and correcting pyrite problems.
This protocol was developed by the Quebec Technical Committee on Pyrite and is now the reference recommended by organizations such as ACQC and OACIQ.
DB certified replacement materials (compliant aggregate containing no pyrite, CTQ-M100 standard)
Advantages of Our Pyrite Services
Recognized Expertise
Pyrite removal according to CTQ-M200 protocol recommended by experts
Complete Assessment
Professional inspection and soil tests included to confirm presence and swelling index
Certified Materials
DB certified backfill (non-swelling aggregates) guaranteeing durability
Complete Management
From A to Z: municipal permits, regulatory disposal of materials
Grant Assistance
Support for RénoRégion, RénoClimat programs, municipal aid
Complete Warranty
Guaranteed work and materials, durable solution compliant with standards
Our Decontamination Process
1. Inspection and Assessment
Thorough visual inspection of slab and backfill. Search for indicator signs (cracks, deformation, white efflorescence). Sample collection for laboratory analysis (IPPG index). Report compliant with CTQ-M200 protocol.
2. Quote and Planning
Detailed quote according to ACQC standards: work, materials, cost, timeline. Discussion of options and possible phasing. Planning according to your availability and seasonal constraints.
3. Site Preparation
Protection of unaffected areas (dust covers). Safety measures (fencing, signage). Controlled demolition of existing slab. Temporary shoring if necessary.
4. Excavation and Replacement
Complete excavation of contaminated backfill to foundation footing. Transport to authorized sites. Backfilling with DB certified aggregate in compacted layers. Installation of collection drain if necessary.
5. Reconstruction and Finishing
Installation of vapor barrier membrane and reinforcement mesh. Pouring of new concrete slab compliant with standards. Mechanical trowel finish. Concrete curing. Complete cleaning and final inspection.
Frequently Asked Questions
How do I know if I have a pyrite problem?
Common signs: star-shaped cracks on concrete slab, slab heaving, whitish dust, uneven floors, sticking doors, cracks in foundation walls. These symptoms result from pyrite swelling that exerts pressure. Laboratory analysis confirms diagnosis with certainty.
How much does pyrite treatment cost?
Cost varies considerably depending on several factors: area to treat, site accessibility, work complexity, required excavation depth and structure type (house, garage, shed). Each project is unique. Contact us for a free assessment and detailed quote adapted to your situation. Financial aid programs sometimes exist (municipal grants, RénoRégion, RénoClimat programs) to reduce costs.
How long does the work take?
Standard project: 2 to 4 weeks from start to finish. Simple garage: 1 to 2 weeks. Full basement: 3 to 4 weeks. Timeline includes preparation, excavation, replacement, slab pouring and concrete curing time. We provide precise schedule with quote.
Can I live in my house during the work?
Yes, in most cases. Work focuses on basement/garage and does not prevent upper floor occupancy. Expect noise and dust during the day. We install dust covers, vacuum systems, and maintain access to living areas. Generally not necessary to move out.
Areas Served
Archi-Maitre Excavation offers pyrite decontamination services throughout the greater Montreal area.
Don't hesitate to contact us for an assessment – our pyrite experts travel quickly to secure your foundations.
Get Your Free Quote
Fill out the form and we'll contact you quickly