Skip to content 
Basement Waterproofing — Interior & Exterior Solutions
Delex Plumbing provides interior and exterior basement waterproofing for Mississauga homes — from hydraulic cement crack injection and interior drainage systems to full exterior membrane application. Licensed, insured, and backed by a written warranty on every installation.
Wet Basement? Understanding the Water Entry Points
Basement water intrusion enters through four pathways: wall cracks (hairline or structural), the wall-floor joint (a common failure point where the poured concrete floor meets the foundation wall), window well overflow (water ponding around basement windows), and hydrostatic pressure (the weight of saturated soil forcing water through porous block or poured concrete).
Correctly identifying the entry point before choosing a waterproofing method is essential. A wall crack requires different treatment than hydrostatic seepage through porous block. We assess each basement individually and provide a detailed diagnosis before recommending interior or exterior waterproofing.
Basement water entry is one of the leading causes of property value reduction in Mississauga. A wet basement disclosed during a real estate transaction can reduce the offered price by $10,000 to $30,000 — far more than the cost of waterproofing. Homeowners who address basement water entry before listing their property consistently see better offers and fewer conditional clauses related to the basement.
The long-term consequence of ignoring basement water entry is mould. Mould growth begins within 24 to 48 hours of persistent moisture and spreads through porous materials including drywall, framing, insulation, and OSB sheathing. Once established, mould remediation costs $2,000 to $15,000 depending on the extent of spread — costs that preventive waterproofing would have avoided entirely.
Interior Basement Waterproofing
Interior waterproofing manages water that enters the foundation rather than preventing it at the source. The approach involves cutting a perimeter drainage channel inside the foundation wall footing, installing a drainage membrane (dimple mat) against the wall, and routing collected water to a sump pump for discharge. A concrete cap over the drainage channel maintains an accessible, clean-looking finish.
Interior waterproofing is less disruptive and less expensive than exterior waterproofing because it does not require excavation around the foundation. It is the correct approach for managing hydrostatic pressure seepage and wall-floor joint leakage in foundations that are structurally sound.
Foundation Crack Injection
Poured concrete foundation walls develop hairline cracks from concrete curing shrinkage and from building settlement. These cracks allow water to enter but do not represent a structural problem. We inject them with polyurethane foam (for active wet cracks) or epoxy resin (for dry structural cracks), filling the crack from the interior surface through to the exterior face.
A properly injected crack forms a permanent waterproof seal that becomes harder than the surrounding concrete. This is a significantly lower cost solution than full interior drainage for foundations where isolated cracks are the primary water entry point.
Exterior Basement Waterproofing
Exterior waterproofing treats the foundation at the source — applying a waterproof membrane directly to the exterior foundation wall before water can enter. It requires excavating around the foundation to expose the wall from grade to footing, cleaning the wall surface, applying a waterproof membrane, installing a drainage board and weeping tile, and backfilling.
Exterior waterproofing is the most effective long-term solution but the most expensive and disruptive. It is appropriate when interior methods cannot adequately manage the volume of water, when the foundation wall itself requires inspection and repair, or when new landscaping or hardscaping is being installed anyway.
Window Well Drainage
Basement windows below grade are surrounded by window wells — curved metal or plastic forms that hold back the soil and allow light into the below-grade window. When window well drains clog or the window well is undersized for the local rainfall, water ponds in the well and enters through the window frame.
We install proper drainage at the bottom of window wells, connected to the weeping tile system or to a daylight outlet, and size window wells appropriately for each window opening. Window well covers prevent leaf and debris accumulation that leads to drain clogging.
Basement Waterproofing Service Area
We provide basement waterproofing across all Mississauga neighbourhoods. Peel Region backflow and basement plumbing subsidy programs may apply for eligible flood-risk properties — including backwater valve installation. Call 416-910-2550.
Same-Day Service — Mississauga's Most Responsive Plumbing Team
Same-day plumbing service in Mississauga is available when you call before 10 a.m. on weekdays. We confirm a two-hour arrival window during your call and send a text notification when the plumber is 30 minutes away. If any scheduling change affects your window, our dispatcher calls you proactively — we do not leave clients waiting without information.
Our service vehicles are stocked with the 50 most commonly needed repair parts and materials. For the majority of Mississauga residential plumbing calls, this means the repair is completed on the first visit without a parts run to the supplier. On the rare occasion where a specialized part is required, we have established same-day supplier relationships and can typically complete the repair the same day in most cases.
Evening and weekend appointments are available for non-emergency work by advance booking. We schedule these appointments at the same flat-rate pricing as weekday service — no premium for Saturday or early evening availability. For clients who cannot take time off work for a plumbing appointment, we provide the weekday scheduling flexibility that makes routine service accessible without using vacation time.
Our service area covers every Mississauga postal code, from L4T in Malton to L5J in Clarkson, and from L5A in Cooksville to L5B in the Square One district. We do not charge additional fees for properties at the outer boundaries of our service area — Mississauga is our home territory and all points within it receive the same response standard.
Waterproofing During Renovation — Timing & Integration
Basement waterproofing is most efficiently integrated with other basement work rather than done as a standalone project. A homeowner who is already excavating for egress windows, installing weeping tile, or finishing the basement has an opportunity to address waterproofing at the same time — when the walls are already open or the floor is already cut — at significantly lower combined cost than two separate projects.
For basement finishing projects specifically, waterproofing is a prerequisite rather than an option. Building insulation and drywall applied to a wet basement wall creates mould conditions within the first winter. We perform waterproofing assessment and any required remediation before the basement finishing framing begins, confirming dry conditions before expensive finishing materials are installed.
Exterior waterproofing integrated with landscaping renovations — where the excavation for a new retaining wall, garden bed, or driveway extension already exposes the foundation — allows the exterior membrane to be applied at minimal incremental cost. We coordinate with landscape contractors on the timing of exterior waterproofing work to take advantage of planned excavation windows.
Foundation drainage improvements during waterproofing work — replacing failed weeping tile, installing a new sump pit, or adding a window well drain — are most efficiently done during the waterproofing project when the perimeter is already excavated or the floor is already cut for the interior drainage channel. Combining these elements in a single project reduces the total disruption and cost compared to addressing each separately.
Why Mississauga Homeowners Choose Delex Plumbing
Delex Plumbing has built its reputation across Mississauga through 10 years of consistent service — same-day response, flat-rate pricing with no surprise charges, and licensed master plumbers on every job. Our 384 verified five-star Google reviews reflect the cumulative experience of homeowners from Port Credit to Meadowvale who called us once for a routine repair and have called back for every plumbing need since.
The three things our clients most consistently cite in their reviews: we arrived when we said we would, the invoice matched the quote, and the plumber left the work area clean. These are not exceptional standards — they are baseline professional standards that should characterize every service business. We treat them as the floor rather than the ceiling of what our service delivers.
Our flat-rate pricing policy means the quote we provide before touching anything is the amount on your invoice when we leave. No overtime charges for after-hours calls. No travel fees for distances within our service area. No material markups disclosed after the job is done. Transparent pricing is how we have maintained a 5.0-star rating across 384 reviews — clients who receive exactly what they were quoted do not leave one-star reviews.
We back every job with a written labour warranty. If something we installed or repaired fails within the warranty period, we return and fix it at no charge. No runaround, no dispute about scope. The warranty documentation is included with the invoice and specifies the exact duration and scope of coverage. For fixture and material warranties from manufacturers, we register the installation and provide the registration confirmation so warranty claims go smoothly without paperwork obstacles.
Licensed & Insured — Basement Waterproofing by Certified Professionals
Every plumber on the Delex team holds a valid Certificate of Qualification from the Ontario College of Trades. This licence is not a formality — it is the legal prerequisite for performing plumbing work in Ontario, and it represents a minimum of 9,000 hours of apprenticeship training plus a journeyman examination that tests both technical knowledge and code compliance.
Full liability insurance protects your property if any accidental damage occurs during our work. Bonded coverage protects you from any dishonesty by our employees while on your property. WSIB coverage protects you from any liability if a worker is injured on your property. These are not optional additions to our service — they are standard protections that every legitimate plumbing company carries and that unlicensed operators routinely lack.
We pull permits for all work that requires them. Ontario Building Code requires permits for new plumbing installations, changes to drain and vent systems, and water heater replacements. A job done without a required permit leaves you without a legally completed installation — a disclosure obligation in real estate transactions and a potential coverage issue in insurance claims. Our permit fees are included in the project quote rather than added as a surprise at the end.
Frequently Asked Questions About Emergency Plumbing
Q: How much does basement waterproofing cost in Mississauga?
A: Interior drainage system installation typically costs $4,000 to $10,000 for a standard home depending on perimeter length and sump pump inclusion. Foundation crack injection costs $400 to $800 per crack. Exterior waterproofing costs $15,000 to $40,000 depending on excavation scope. Call 416-910-2550 for a free on-site assessment.
Q: Is interior or exterior waterproofing better?
A: Both have their place. Exterior waterproofing prevents water from entering the foundation and is the most comprehensive solution. Interior waterproofing manages water that has already entered, at significantly lower cost and disruption. We recommend interior solutions in most cases and exterior when the water volume or foundation condition requires it.
Q: Will basement waterproofing stop the smell in my basement?
A: Yes in most cases. Musty basement smells are caused by mold and mildew growth in persistently wet conditions. Once the moisture is eliminated by waterproofing, the existing mold dries and becomes inactive. Established mold on drywall or framing may require remediation before dryness alone resolves the smell.
Get Your Free Estimate Today!
Or Give Us A Call: 416-910-2550
Licensed & Insured
Trusted Local Plumbers 
Fast Response
Usually Within 1 Hour 
Satisfaction Guaranteed
100% Quality Work Free Estimate — Call 416-910-2550
Every waterproofing job starts with a free on-site assessment and estimate. Call 416-910-2550 or book online.
The free assessment includes a visual inspection of the foundation walls, an assessment of window well drainage, confirmation of sump pump operation, and a review of any historical flooding records the homeowner can provide. This assessment takes approximately 30 to 45 minutes and results in a detailed written estimate covering all recommended waterproofing measures with cost and priority ranking. The estimate is provided at no charge and without obligation to proceed.
We present waterproofing options at multiple price points — from a targeted crack injection to a comprehensive interior drainage system. The homeowner chooses the level of protection that fits their budget. Contact us or request service online to schedule your free assessment.
