Exterior membrane, French drain, sump pit and backwater valve: a complete system to keep your basement dry, carried out after a site visit and a written quote.
or call (514) 654-9184
French drain & waterproofing
Basement leaks, a clogged drain or sewer backups: we waterproof your foundation walls from the outside and install a complete drainage system, from the French drain to the backwater valve.
A damp basement often comes from groundwater that is no longer carried away from the foundation. The French drain, a perforated pipe laid at the base of the walls, collects that water and directs it to a sump or to the sewer. If it is clogged, crushed or missing, water builds up against the walls and eventually seeps in.
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Construction AIM waterproofs foundations from the outside, from excavation to backfill, with a quote that states what is included and what is not.
A drain laid at footing level, all around the building: a BNQ-certified rigid drain covered with clean stone, or a drain in crushed stone wrapped in geotextile. Cleanouts let us inspect and clean it.
A dimpled high-density polyethylene sheet. Against the wall, it creates an air gap: water runs down by gravity to the drain instead of passing through the concrete. Mechanically fastened from the base of the footing to above finished grade.
Depending on the lot and the sewer level, the drain empties into a sump basin connected to the sewer, into a dry well or into a gravity drainage system. A new basin, or reuse of the old one's location when possible.
During heavy rain, the municipal sewer can back up into basements. The backwater valve lets wastewater out but stops it from coming back. Installed by a qualified plumber, it must remain accessible for maintenance.
Once the walls are exposed, the cracks are visible over their full height. We repair active cracks with mortar or epoxy injection before installing the membrane. The quote states how many cracks are included.
Free-draining granular backfill compacted in layers, or excavated material depending on the project, then a slope of at least 5% over 1.5 m from the walls to keep surface water away. Spot corrections on request (door sill, dryer vent).
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A site visit finds where the water comes from: a clogged or missing drain, a foundation that is no longer watertight or a sewer backup.
White stains on the concrete, a musty smell or moisture at the bottom of the walls: groundwater is staying in contact with the foundation. The drain or the membrane is no longer doing its job.
Water that appears after rain, or a sump that no longer receives anything, points to a clogged, crushed or missing drain. An inspection confirms it.
A backup during heavy rain, or a crack that lets water through, calls for prompt work: backwater valve, crack repair and waterproofing.
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Our quotes list the exclusions. Any addition is presented to you in writing and approved before it is carried out.
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One job, one person in charge, from excavation to backfill.
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Membrane, drain, sump, valve and backfill: one job, one point of contact.
In Montreal, an excavation permit may be required depending on the depth and the distance from the public right-of-way. Permits are excluded from our quotes and coordinated with you.
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The parts of a foundation drainage system, and what each one does.
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We waterproof foundations and replace French drains in Montreal, on the North Shore, including Laval, and on the South Shore, from our office in Anjou, in Montreal's East End.
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Water or moisture at the bottom of the basement walls, white stains on the concrete, a musty smell, or a sump that stays dry after rain. A site visit lets us assess the situation.
The drain carries water away at the base of the foundation, but it does not protect the wall over its height. The membrane keeps water away from the concrete and directs it to the drain.
The by-law on the protection of buildings against sewer backups (11-010) requires a valve for plumbing fixtures and floor drains located below street level. Your borough can tell you which rules apply to your building.
In Montreal, an excavation permit may be required depending on the depth of the excavation and its distance from the public right-of-way; other authorizations vary by borough. Permits are excluded from our quotes and are generally obtained by the owner, in coordination with us.
The City of Montreal information sheet on By-law 11-010 (in French) states that French drain water is directed to a sump pit inside the building, from which a pump sends it to the sewer. Requirements can vary by municipality and type of work: we check them with you before the job.
In Montreal, downspouts must discharge onto a permeable surface, such as a lawn or a flower bed, at least 1.5 m from the foundation (By-law 20-030). A downspout that empties at the base of the wall adds water to the soil, which the drain then has to carry away.
Our prices are based on the current wage rates of the Commission de la construction du Québec (CCQ), set by the collective agreements for the sector concerned (residential, institutional and commercial, industrial), plus the materials and equipment specific to each job. Every quote is free, detailed and prepared after a site visit.
The most common signs: water or white stains at the bottom of the basement walls, a damp smell, water pooling near the foundation after rain. A camera inspection of the drain confirms whether it is clogged, crushed or missing before choosing between cleaning, repair or replacement.
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Our guides on waterproofing and drainage.
The steps: excavation, membrane, drain and free-draining backfill.
Read the guide →Sheet 02 · GuideCamera inspection, cleaning or replacement, and permits.
Read the guide →Sheet 03 · GuideHow it protects the basement and how to maintain it.
Read the guide →Next step
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Describe my projectPage updated October 17, 2026.
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