Exterior waterproofing addresses water at the source — before it ever reaches the foundation wall. Full excavation, Duraflex membrane, new weeping tile. The most complete protection available for any basement.
Exterior waterproofing is the gold standard in basement and foundation protection. By excavating to the base of the foundation wall, we expose the full exterior face, apply a Duraflex rubberized waterproofing membrane, install drainage board, and replace the weeping tile with new perforated pipe in clear stone. The result is a true waterproof barrier between the soil and the foundation wall — the most comprehensive solution available and the same standard applied to new construction.
The logic of exterior waterproofing is straightforward: water cannot damage what it cannot reach. Interior waterproofing systems manage water after it has entered the wall. Exterior waterproofing stops it before it makes contact with the foundation at all. The foundation material — whether poured concrete or block — never gets wet. It cannot spall, corrode rebar, or be degraded by freeze-thaw cycling of moisture trapped inside it. This is why exterior waterproofing is the standard specified in current Ontario building codes for new construction. It is not the latest innovation in waterproofing — it is the recognized best practice.
Most existing homes were built with tar-based dampproofing, not true waterproofing. That coating resists moisture vapour, not liquid water under pressure. Over time it cracks, peels, and separates from the wall. Once it fails, the foundation faces hydrostatic pressure from saturated soil with no meaningful protection. Replacing that failed dampproofing with a Duraflex exterior membrane system restores the level of protection the home should have had from the beginning — and does it permanently. This is the reason homeowners who have tried other approaches and continue to deal with water problems ultimately choose exterior waterproofing.
We perform exterior waterproofing throughout Napanee, Belleville, Kingston, Deseronto, Bath, and surrounding communities. Every project starts with a thorough assessment of the foundation — the type of wall, the drainage conditions, the soil character, and the specific pattern of water entry. From that assessment, we give you a clear written estimate that explains what we will do, in what sequence, with what materials, and what the result will be. We have been doing this work in Eastern Ontario for years and we understand the conditions — the clay-heavy soils, the water table behaviour, the freeze-thaw pressures — that our foundations face.
Not every basement water problem requires exterior excavation — but certain conditions consistently point to exterior waterproofing as the most effective and permanent solution. These are the indicators we look for when assessing a foundation.
Water entering through several cracks, joints, and porous sections simultaneously points to a perimeter-wide problem best solved from the exterior. When water is coming in at multiple points across the wall face, the issue is the condition of the exterior, not individual cracks.
Cracks that have been repaired multiple times and keep returning indicate ongoing movement and pressure that needs to be addressed at the source. Exterior work that removes soil pressure and applies a flexible membrane stops the cycle of crack recurrence.
Concrete that is crumbling, spalling, or showing significant face deterioration needs exterior work to stop the source of moisture damage. Spalling progresses as long as moisture continues to reach the concrete — exterior waterproofing removes that moisture source permanently.
Homes with aging dampproofing coatings from original construction or failed previous exterior membranes need the exterior face fully re-done. A failed system cannot be patched from the inside — it needs to be replaced at the surface where it was applied.
Homes built without a functional weeping tile system need exterior excavation to install one properly at foundation footing level. A drainage system cannot be properly installed at footing depth without exposing the exterior of the foundation wall.
Buying an older home is an opportunity to verify the foundation condition and address it before moving in. Many older homes require exterior work to bring them to current standards — and doing it before the basement is finished or furnished is far less disruptive.
Horizontal cracks indicating serious lateral pressure mean the exterior soil and drainage conditions must be addressed, not just the crack itself. Relieving soil pressure through exterior drainage is a critical part of managing foundations with horizontal cracking.
Homeowners who want the problem solved once and definitively choose exterior waterproofing because it stops water before it reaches the wall. It is the approach that addresses root cause rather than managing consequences — and the one that lasts the longest.
Foundation water problems that require exterior waterproofing all trace back to conditions on the outside of the wall. Understanding those conditions is what allows us to address them correctly and permanently — not just seal the visible symptom from the inside.
Most Ontario homes built before the 1990s have only tar dampproofing on the exterior wall face — a coating that resists moisture vapour but was never designed to hold against liquid water pressure. With age, tar-based coatings become brittle, crack, and separate from the wall in sheets. Once that coating fails, the foundation is exposed to full hydrostatic pressure with no protection. This is the most common condition we find when we excavate older foundations.
Soil that holds water exerts hydrostatic pressure against the full height of the foundation wall. In clay-heavy soils common across Eastern Ontario, this pressure can persist for days or weeks after a rain event. Exterior drainage — through drainage board and properly installed weeping tile — removes this pressure at the source rather than forcing the foundation wall to resist it indefinitely.
Clay tile from older construction or old perforated pipe that has collapsed, fractured at joints, or silted up means groundwater has no drainage path away from the foundation. Without a functioning weeping tile system, water accumulates at the base of the wall and builds up against the full exterior face. Exterior excavation is the only way to replace the weeping tile at the depth it needs to function.
Ontario winters cause repeated freeze-thaw cycles that crack and degrade foundation membranes and drive moisture deeper into the foundation material. Water that enters the concrete during warmer months freezes, expands by about 9% in volume, and progressively widens cracks and spalls the wall face. Each freeze-thaw cycle damages a wet foundation more than the one before it.
Sites where water naturally flows toward the house — due to grading, neighbouring lots, or lot topography — mean constant moisture accumulation against the foundation that must be managed by a proper exterior system. No amount of interior waterproofing changes the fact that the exterior face of the foundation is continuously exposed to water. Exterior waterproofing with proper drainage is the appropriate response to adverse site drainage conditions.
Concrete foundations over 30 years old have naturally increased porosity and surface degradation that allows water infiltration across the entire wall face — not just through discrete cracks. As concrete ages, the paste matrix between aggregate particles opens up, creating pathways for water under pressure. An exterior membrane applied to the full wall face addresses this distributed permeability that targeted crack injection cannot solve.
Roots growing along the exterior wall can damage existing waterproofing coatings and open pathways for water entry. Mature trees with roots at foundation depth can physically lift and displace drainage board, compromise membrane adhesion, and infiltrate weeping tile systems — blocking drainage and forcing water against the wall. Exterior work allows us to identify and address root damage that is invisible from the interior.
Differential settlement that has opened cracks in the exterior face of the foundation is best addressed during exterior work. Settlement cracks are often wider at the exterior face than at the interior surface — sometimes dramatically so. Interior crack injection from the inside under-fills the true void; exterior access allows us to repair the crack at its full width and depth before membrane application covers it permanently.
Exterior waterproofing is not a single product — it is a system of components that work together. Every step in the process matters. The sequence, the preparation, and the quality of each component determines whether the system performs as designed for decades.
We excavate around the exterior of the home to the base of the foundation footing, exposing the complete wall face from footing to grade. This gives us access to the full height of the foundation — not just the area near grade — and allows us to address every issue on the exterior surface before applying the waterproofing system. Excavation is performed carefully, with equipment kept at safe distances from the wall to avoid loading the foundation with machine weight. Topsoil is stripped and set aside for replacement. The excavation remains open until all waterproofing work is inspected and approved.
Footing-to-Grade Access Topsoil Preservation Careful Equipment OperationBefore any membrane goes on, we clean the entire wall face, remove any deteriorated or loose material, and repair all cracks and voids. This preparation stage is what separates a system that lasts from one that fails early. A membrane applied to a dirty, degraded, or cracked surface will not bond properly — and unbonded sections are where water finds its way in. Exterior crack repair at this stage is far more effective than interior methods because we access the full depth of each crack from the outside. Settlement cracks that appear as hairlines from the interior are often several millimetres wide at the exterior face — and we fill them fully before the membrane goes on.
Full Wall Cleaning Exterior Crack Repair Surface PreparationOur primary waterproofing layer. Duraflex is a thick, polymer-modified rubberized membrane applied to the full height of the exterior wall from footing to above grade. It is applied as a liquid that bonds directly to the concrete, fills surface irregularities, and cures to a seamless, fully adhered waterproof barrier. Unlike rigid coatings or sheet membranes, Duraflex remains flexible through Ontario's freeze-thaw cycles — it moves with the foundation rather than cracking under thermal stress. It is the same membrane standard used in current new construction in Ontario, and we are certified applicators of the system.
Penetrations — pipe entry points, tie rod holes, form tie locations — are all detailed before membrane application so that no point of vulnerability is left unsealed. The membrane is applied in the correct thickness across the full surface. There are no seams, laps, or joints that can open over time. The finished result is a continuous, fully bonded waterproof layer from the footing to above the finished grade line.
Duraflex Certified Full-Height Application Penetration DetailingA dimple drainage board is installed over the membrane for the full height of the excavation. The drainage board serves two purposes: it protects the membrane from damage during backfilling, and it creates an air gap between the soil and the membrane surface. This air gap means that water moving through the backfill soil does not press directly against the membrane — it travels downward through the drainage plane to the weeping tile at the base of the footing. Without drainage board, even a perfect membrane faces the direct hydrostatic pressure of saturated soil. With it, that pressure is redirected downward before it can build against the wall.
Membrane Protection Drainage Plane Pressure ReliefNew perforated drainage pipe is installed at the base of the footing in a bed of clear stone and wrapped in filter fabric to prevent silting over time. This restores — or in many cases establishes for the first time — a functional drainage system at the level where groundwater accumulates. The weeping tile carries water that reaches the footing level away from the foundation to daylight or to a sump system. The excavation is then backfilled in staged lifts using drainage stone at the footing level transitioning to native soil above, with the grade restored to slope away from the foundation at a minimum 5% grade. Where topsoil was preserved, it is replaced and sod is restored where possible.
New Perforated Pipe Clear Stone Bed Filter Fabric Wrap Grade RestorationExterior waterproofing is the most significant foundation investment most homeowners make. Once it is backfilled, it is invisible — which means the quality of the work is entirely in the hands of the contractor. Here is what we bring to every exterior waterproofing project.
We are certified applicators of Duraflex waterproofing systems — the same products used in current new construction standards. Certification means trained surface preparation, correct application thickness, proper penetration detailing, and installation technique that matches the system design. The membrane is only as good as the person applying it.
We don't apply membrane to an unprepared surface. Proper wall cleaning, deteriorated material removal, and crack repair before membrane application is what separates a lasting result from a temporary one. Preparation is the most important step in exterior waterproofing and the one most commonly skipped by contractors cutting corners.
We backfill with drainage stone at the footing level, not native soil. On clay-heavy lots, native soil packed against the footing prevents water from reaching the weeping tile — defeating the purpose of the drainage system. Clear stone at the footing level is what allows the weeping tile to function as designed through every spring thaw.
Every exterior waterproofing project includes a written workmanship guarantee. If the system fails due to our installation, we return and address it at no cost. The warranty is documented in your estimate before work begins — not offered verbally after the fact. We stand behind the work because we are confident in how it is done.
We restore the grade, replace sod where possible, and leave the site clean when we are done. Exterior waterproofing requires significant excavation — we take the restoration as seriously as the waterproofing itself. Topsoil is preserved during excavation and replaced during backfill. The finished property looks like we were there, not like we left.
We provide a detailed written estimate before any work begins so you know exactly what will be done and what it will cost. No surprises on project scope, no additions after the job starts. If conditions during excavation reveal something unexpected, we discuss it with you before proceeding — not after.
The membrane is the core of any exterior waterproofing system. Every other component — the drainage board, the weeping tile, the backfill — supports and protects the membrane. The membrane itself is what actually stops water from reaching the foundation wall. We use Duraflex because it is the best-performing product available for the conditions Ontario foundations face.
Duraflex is a polymer-modified rubberized waterproofing membrane. Unlike traditional tar-based dampproofing — which is a rigid, brittle coating that cracks under thermal stress and cannot withstand hydrostatic pressure — Duraflex is formulated to remain permanently flexible. It moves with the foundation through seasonal temperature changes and freeze-thaw cycling without cracking or delaminating. A membrane that cracks is not a waterproof membrane. Duraflex doesn't crack. That is the single most important characteristic for a product buried in Ontario soil.
It bonds directly to concrete and block in a liquid-applied process that eliminates seams, laps, and joints — the weak points in sheet-applied membrane systems where water finds entry over time. The liquid application also means that surface irregularities, form tie holes, and minor honeycombing in the concrete are all encapsulated by the membrane rather than bridged over. The bond to the substrate is what keeps hydrostatic pressure from lifting or separating the membrane under sustained water pressure. We have seen Duraflex membranes we applied years ago on properties we've returned to — still fully bonded, still flexible, still performing exactly as specified.
Professional-grade rubberized waterproofing membrane. The standard for certified exterior foundation waterproofing across Canada.
AW Waterproofing Solutions holds Duraflex installer certification. That means trained application technique, correct product specification, proper surface preparation standards, and full system installation — membrane, drainage board, and drainage integration — done according to the manufacturer's design intent. When we apply Duraflex to your foundation, we are doing it the way it was designed to be applied, by people who were trained on exactly that.
Exterior waterproofing work opens up things you cannot see from the inside of a basement. These are observations we have made in the field across years of excavating and waterproofing foundations in Eastern Ontario — the things that only become clear when you are standing beside an exposed foundation wall.
We excavated to the footing on a 1975 home and found the original tar coating had completely separated from the wall in sheets. The foundation had been essentially unprotected for years — maybe decades. The homeowner had no idea because the dampproofing was never visible from the interior. The water entering the basement was coming through the wall face, not through cracks. No interior system addresses that condition at its source.
A homeowner had been managing a wet basement with a sump pump for 15 years. The pump ran every hour through spring and summer — constantly cycling, draining the water that built up against the foundation. After exterior waterproofing with new weeping tile, the pump runs twice a week during spring thaw. The water pressure that had been building against the wall for 15 years now drains away before it accumulates. The pump is still there as the final line of defence. It just almost never needs to run.
We found tree roots had grown along the full length of one wall, physically lifting the drainage board away from the membrane on the previous system. The roots had found the gap between the membrane and the drainage board — which gives slightly — and followed it horizontally across the wall. Every joint in the old drainage board was pried open by root growth. The membrane underneath was intact, but the drainage plane was completely compromised. The weeping tile at the base of the wall was also infiltrated by roots and had stopped functioning.
Exterior excavation cost more than an interior system — but it was the right answer for this property. The water table in this location rose above the floor slab level in spring. An interior drainage channel and sump pump could have managed the water, but the hydrostatic pressure against the exterior wall face would have continued, and the foundation material would have continued to degrade. Only removing the pressure from outside — with drainage board, weeping tile, and membrane — actually solved the problem rather than managing the consequence of it.
A crack that had been injected from the interior three times kept returning. Each injection sealed it and held for a season or two before water reappeared. Exterior excavation revealed the reason: the crack was 8mm wide at the exterior face but only 1mm at the interior surface. Three rounds of interior injection had been filling the narrow interior end of a much larger void. The crack was never fully repaired. Exterior access, proper crack repair from the outside, and then membrane application over the repaired surface resolved it permanently.
The drainage stone from the original installation had been replaced with native clay during a previous repair — completely blocking drainage to the weeping tile. A section of the weeping tile had been damaged and repaired by a previous contractor who backfilled with whatever was at hand. Clay packed against the weeping tile inlet means water cannot reach the pipe. Starting fresh — new pipe, new drainage stone, new filter fabric — was the only option. The existing system had been non-functional for years without the homeowner knowing.
We repaired a poured concrete wall and found three cold joint locations where concrete had been poured in separate lifts decades ago — visible as horizontal lines in the exterior face of the wall. All three were entry points for water that appeared from the interior to be simple horizontal cracks. They were not cracks — they were construction joints between different concrete pours that had opened over time. Exterior access made it possible to identify them correctly and seal them with the appropriate repair materials before membrane application.
A new homebuyer commissioned exterior waterproofing before moving in. We found the original 1960s clay weeping tile had completely collapsed on two sides of the house — the pipes had fragmented into short sections that had settled into the soil around them, leaving no continuous drainage path. The foundation had had no functional perimeter drainage for an unknown number of years. The new owners had no way of knowing this from the inspection report. Opening the exterior revealed it immediately.
Backfilling with proper drainage stone rather than native soil makes a difference that shows up every spring. On clay-heavy lots, native soil packed against the footing level does not allow water to migrate to the weeping tile — the clay holds the water in place. Without drainage stone creating the permeable zone at footing level, the weeping tile sits in clay and cannot do its job. We see this on properties where previous exterior waterproofing was done without attention to backfill specification. The membrane was fine. The drainage failed. The basement still got wet.
The Duraflex membrane we applied six years ago on a similar property is still in perfect condition — fully bonded, flexible, uncracked. We returned to that property for an unrelated repair and had the opportunity to expose a small section. The material performs exactly as specified. That is what Duraflex does that tar-based dampproofing cannot: it stays flexible and bonded through years of thermal cycling, freeze-thaw stress, and sustained hydrostatic pressure. After six Ontario winters, it looks the same as it did on application day.
Both approaches produce a dry basement when properly installed — but they work by different mechanisms, suit different situations, and carry different costs. Understanding the distinction is essential to choosing the right solution for your home and your problem.
| Factor | Exterior Waterproofing | Interior Waterproofing |
|---|---|---|
| Water Stopped At | Exterior wall face — before it contacts the foundation | Captured after entering the wall; managed before reaching living space |
| Excavation Required | Yes — full excavation to footing depth required | No — all work is done inside the basement |
| Landscaping Impact | Significant — excavation affects foundation perimeter plantings and grade | None — no exterior work involved |
| Handles High Water Table | Yes — weeping tile at footing relieves pressure before it builds against wall | Partially — sump pump removes water but foundation wall still under pressure |
| Addresses Root Cause | Yes — stops water at the source, protects foundation material | No — manages consequences; foundation material continues to be exposed to moisture |
| Cost Level | Higher — excavation, membrane, drainage board, weeping tile, backfill | Lower — interior drainage channel and sump pump only |
| Time to Complete | 3–5 days for average home | 1–3 days for average home |
| Best Candidate | Wall seepage from multiple locations, failed exterior membrane, high water table, new weeping tile needed, definitive long-term solution | Floor seepage, floor-wall joint leaks, limited exterior access, interior-only budget, or as a complement to exterior work |
These are the questions homeowners ask us most when they're considering exterior waterproofing. If yours isn't here, call us — we give straight answers.
Exterior basement waterproofing is the process of excavating around the outside of a home's foundation down to the footing, preparing the wall surface, applying a rubberized waterproof membrane (Duraflex) to the full exterior wall face, installing drainage board over the membrane, and replacing the weeping tile at the footing with new perforated pipe in clear stone. The result is a true waterproof barrier on the exterior face of the foundation — stopping water before it ever contacts the wall structure. It is the most comprehensive basement waterproofing method available and the same standard applied to new construction in Ontario.
Exterior basement waterproofing typically takes three to five days for an average home, depending on the perimeter length being excavated, the depth of the foundation, site access conditions, and the extent of any wall preparation or foundation crack repair required before membrane application. More complex foundations, difficult soil conditions, or limited equipment access can extend the timeline. We provide a specific and realistic project timeline in your written estimate before work begins and keep you updated throughout.
Exterior waterproofing requires excavation along the foundation walls, which affects the landscaping in those areas. We remove topsoil carefully and set it aside for replacement, protect existing plants and hardscaping where possible, and restore the grade after backfilling. Sod is replaced where conditions allow. We discuss landscaping impact clearly during the estimate — large established trees, patios, decks, or walkways near the foundation are factors we assess in advance and factor into our approach. We leave the site in clean, restored condition when the work is complete.
We excavate to the base of the foundation footing — the full depth of the foundation wall. For most residential foundations in Ontario, this is typically six to eight feet below finished grade, though deeper foundations exist. Full-depth excavation is essential for two reasons: it gives us access to the complete exterior wall face for membrane application, and it allows us to install new weeping tile at footing level — the only depth at which a drainage system can actually relieve hydrostatic pressure from groundwater accumulation.
Duraflex is a polymer-modified rubberized waterproofing membrane applied as a liquid directly to the exterior foundation wall. It bonds to the concrete and cures to a seamless, flexible waterproof barrier that resists liquid water under sustained hydrostatic pressure. Standard dampproofing — the tar-based coating applied to most homes built before the 1990s — resists only moisture vapour and is not designed to hold against liquid water pressure. Dampproofing also becomes brittle with age and cracks under freeze-thaw cycling. Duraflex remains flexible through decades of thermal cycling, stays bonded to the substrate, and provides true waterproofing, not just moisture resistance. It is the same standard used in current Ontario new construction.
Exterior waterproofing stops water at the source — it prevents it from reaching the foundation wall at all, which protects the foundation material from ongoing degradation. Interior waterproofing intercepts water that has already entered the wall and manages it before it damages the living space. For wall seepage, failed exterior membranes, and situations requiring new weeping tile, exterior waterproofing is the most complete solution. For floor seepage, water coming through the floor-wall joint, limited exterior access, or situations where budget or site conditions make excavation impractical, interior waterproofing is often the right answer for a wet basement repair. Many foundations benefit from both. We assess each situation individually and recommend what actually fits the problem.
During exterior waterproofing we excavate to the footing and have full access to the existing weeping tile at the base of the wall. We assess the condition of the existing pipe and in most cases — particularly on homes more than 20 to 30 years old — replace it entirely with new perforated pipe installed in a bed of clear drainage stone and wrapped in filter fabric to prevent silt infiltration over time. Original clay tile has typically collapsed or separated at joints. Older plastic pipe is often crushed, root-infiltrated, or silted up. Replacing the weeping tile as part of the exterior project restores the full drainage system at the depth where it needs to function.
Exterior waterproofing in Ontario is typically performed between spring and fall. Frozen ground makes excavation extremely difficult and costly. The Duraflex membrane also requires minimum surface and ambient temperatures for proper adhesion and curing — application to frozen or frost-affected concrete will not achieve the bond the system needs to function correctly. If you are dealing with an active water problem in winter, we discuss immediate interim measures and schedule exterior waterproofing for appropriate seasonal conditions. Interior drainage system installation can proceed year-round since all work is inside the basement.
Exterior basement waterproofing costs vary based on the perimeter length being excavated, the depth of the foundation, site access conditions, soil type, and the extent of wall preparation and crack repair required. For an average residential home in Ontario, full perimeter exterior waterproofing with Duraflex membrane, drainage board, and new weeping tile typically ranges from $10,000 to $30,000 or more. Partial perimeter work on the most affected sides is less expensive. We provide a detailed written estimate at no charge before any work begins — so you have a clear picture of costs, scope, and timeline before committing to anything.
Yes. Every exterior waterproofing project we complete includes a written workmanship guarantee. If the system fails due to our installation, we return and address it at no cost. Warranty terms are documented in your written estimate before work begins — not offered verbally after the fact. We stand behind exterior waterproofing with full confidence because we use quality materials, certified membrane application, proper drainage stone specification, and careful backfill technique on every project. The quality of the work is what makes the warranty meaningful.
The most complete protection starts here. We provide a free, no-obligation site assessment so you understand exactly what is happening with your foundation and what exterior waterproofing will cost — before any commitment.
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