Cementitious Waterproofing Toronto
Cementitious waterproofing is a cement-based coating system applied to concrete and masonry to form a durable, bonded barrier against water. On commercial and institutional projects, it is used to protect below-grade structures, water-retaining tanks and reservoirs, and reinforced concrete where a rigid, breathable, tightly bonded waterproofing layer is required. Because it bonds integrally to the concrete substrate and can resist water under pressure, cementitious waterproofing is a proven choice for structures that must remain watertight for decades under continuous exposure.
Nusite Group self-performs cementitious waterproofing across the GTA and Southern Ontario. We do not subcontract our waterproofing scopes \u2014 every system is installed by our own crews, backed by 35+ years of experience on large-scale commercial, institutional, and industrial projects. As a fully bonded specialty contractor, licensed across Ontario and insured to $10 million in liability coverage, we deliver cementitious systems as part of a coordinated approach to the building envelope.
What Is Cementitious Waterproofing?
Cementitious waterproofing is a coating formulated from portland cement, fine aggregates, and active waterproofing compounds that is mixed with water (and, in polymer-modified systems, a liquid polymer) and applied to a concrete or masonry substrate. As it cures, it bonds to the substrate and forms a continuous cementitious waterproofing membrane \u2014 a water-resistant layer that becomes part of the structure rather than a loose covering over it.
Two characteristics make it well suited to commercial concrete. First, it develops a strong adhesion to properly prepared concrete, so it resists water pushing against it \u2014 including, in appropriately specified systems, water under hydrostatic pressure from either the positive or negative side. Second, it remains breathable, allowing water vapour to escape while blocking liquid water, which suits below-grade and water-retaining structures where trapped moisture would otherwise be a concern.
Types of Cementitious Waterproofing Systems
Cementitious waterproofing is not a single product but a family of systems, each matched to different substrate, movement, and exposure conditions:
Rigid cementitious coatings. Standard cement-based slurry coatings applied by brush, trowel, or spray to concrete and masonry. They provide a hard, durable barrier well suited to stable substrates that undergo minimal movement.
Polymer-modified cementitious coatings. Cement-based systems modified with a polymer component to add flexibility and improve adhesion and crack-bridging. The added flexibility allows these systems to accommodate minor substrate movement and hairline cracking, making them a common choice where some movement is expected.
Crystalline cementitious systems. Systems containing active chemicals that react with moisture and the constituents of concrete to form insoluble crystals within the concrete’s pore structure, reducing permeability from within and providing a degree of self-sealing at fine cracks. These are frequently used on water-retaining and below-grade structures, and can be applied as coatings or incorporated into the concrete. Learn more on our crystalline waterproofing page.
Selecting among these depends on the substrate condition, the degree of movement the structure undergoes, the water pressure the system must resist, and whether the surface will remain exposed or be covered \u2014 which is why system selection should follow an assessment of the actual project conditions.
Commercial Applications
Nusite Group applies cementitious waterproofing across a range of large-scale commercial and institutional conditions, including:
Below-grade structures. Foundation walls, base slabs, and other below-grade concrete where a bonded barrier resists soil moisture and hydrostatic pressure. Cementitious systems can be applied to the positive or negative side, which is valuable on existing structures where exterior access is limited.
Water-retaining structures. Tanks, reservoirs, and containment structures where the coating must hold water in rather than keep it out. Cementitious systems are well established in these applications for their bond, durability, and suitability for continuous water contact.
Reinforced concrete protection. Structures where keeping water and chlorides out of the concrete protects the embedded reinforcing steel from corrosion \u2014 the mechanism that cracks and deteriorates concrete over time.
Tunnels, pits, and confined structures. Below-grade and confined concrete structures where a bonded, pressure-resistant barrier is required.
In each case, the system is selected and detailed for the specific structure rather than applied as a one-size-fits-all product.
Why Cementitious Waterproofing Is Used on Commercial Concrete
Cementitious waterproofing offers several advantages that make it a durable choice for commercial concrete structures:
Strong bond to concrete. Because it is cement-based and bonds integrally to a prepared substrate, it becomes part of the structure and resists water pressure rather than relying on a mechanical attachment.
Breathability. It blocks liquid water while allowing vapour transmission, reducing the risk of trapped moisture in below-grade and water-retaining structures.
Durability under exposure. Cementitious systems stand up to continuous water contact and the conditions of below-grade and containment structures.
Compatibility with concrete rehabilitation. Because the substrate must be sound for the system to perform, cementitious waterproofing integrates naturally with concrete repair \u2014 deteriorated concrete is restored first, then protected, as a single coordinated scope.
Substrate Preparation and Installation
Cementitious waterproofing performs only on a sound, properly prepared substrate, and the majority of failures trace to preparation rather than the product. Before application, the concrete must be clean, structurally sound, and free of laitance, contaminants, and loose material, with active leaks and cracks addressed and the surface profiled to accept the coating. Where the concrete is deteriorated, spalled, or contaminated, it must be repaired before any waterproofing is applied \u2014 a coating cannot restore compromised concrete, only protect sound concrete.
The system is then mixed to the manufacturer’s specification and applied at the specified thickness, typically in multiple coats, and cured under controlled conditions. Because Nusite Group self-performs this work, substrate preparation, application, and curing are controlled by our own crews rather than divided across subcontractors \u2014 which is where consistent quality on a waterproofing scope is won or lost.
What is cementitious waterproofing?
Cementitious waterproofing is a cement-based coating applied to concrete and masonry that cures to form a bonded, water-resistant barrier. On commercial projects it is used to protect below-grade structures, water-retaining tanks, and reinforced concrete against water penetration.
How long does cementitious waterproofing last?
When applied to a sound, properly prepared substrate by experienced crews, cementitious waterproofing is a long-lasting system that can protect a structure for many years. Service life depends on the substrate condition, the system selected, the exposure, and the quality of surface preparation and installation \u2014 which is why preparation and application discipline matter as much as the product itself.
What are the limitations of cementitious waterproofing?
Standard rigid cementitious coatings have limited ability to bridge cracks or accommodate significant structural movement, so on structures that move, a polymer-modified or crystalline system \u2014 or a different waterproofing approach entirely \u2014 may be more appropriate. It also requires a sound substrate: it protects concrete but does not repair or strengthen it. Selecting the right system for the conditions is what avoids these limitations.
Can cementitious waterproofing resist water under pressure?
Yes. Appropriately specified cementitious systems can resist water under hydrostatic pressure, and certain systems can be applied to the negative side of a structure \u2014 valuable for below-grade and water-retaining structures where exterior access is limited. The right system and detailing for the specific pressure and exposure conditions should be confirmed through assessment.
Cementitious Waterproofing with Nusite Group
Nusite Group has self-performed commercial waterproofing across the GTA and Southern Ontario since 1990, installing cementitious and related systems on below-grade structures, water-retaining structures, and reinforced concrete for institutional, industrial, and large-scale commercial projects. As a fully bonded specialty contractor, licensed across Ontario and insured to $10 million in liability coverage, we assess each structure, prepare the substrate, and install the right system with our own crews \u2014 integrating cementitious waterproofing with concrete rehabilitation where the structure requires restoration before protection.
To discuss your project’s cementitious waterproofing requirements, request a consultation, or invite us to bid or prequalify, contact Nusite Group.
