Cement is one of the most widely used building materials in construction—and for good reason. It’s strong, adaptable, and forms the foundation of many structures. But one thing it’s not? Waterproof.
Despite its durability, cement is naturally porous, meaning it absorbs water over time. This leads to internal moisture buildup, which can affect flooring, walls, joints, and even foundations.
Water absorption causes deterioration in both structural and aesthetic components. Over time, it allows other materials to decay and plant growth or mold to develop indoors—posing health and safety risks.
Many homeowners and contractors still believe cement doesn’t need protection. But without the right waterproofing of the cement substrate, even a small leak or damp patch can lead to long-lasting damage. Waterproofing isn’t optional—it’s essential for every cement-based roofing surface.
The Risks of Leaving Cement Unprotected
Leaving concrete surfaces unprotected allows water and moisture to penetrate deep into the substrate. Here are the most common consequences:
Cracks and Structural Damage
Moisture enters cement, expands during freeze-thaw cycles, and creates pressure within the material. This leads to cracking, structural instability, and foundation damage over time.
Efflorescence and Salt Leaching
When water evaporates from cement, it can leave behind calcium chloride or salt deposits. This process, known as efflorescence, appears as white dust on the surface and is a sign of vapor movement through the concrete.
Mold, Mildew, and Mould
Trapped moisture behind concrete walls or under tile and carpet encourages the growth of mildew and mold. This can cause indoor air issues, deterioration of materials, and health concerns.
Rebar Corrosion
In reinforced concrete, water seeps in and leads to corrosion of internal steel. Rust expands and cracks the surrounding mortar, reducing the lifespan of critical structures.
Reduced Lifespan and Higher Costs
Without proper protection, cement deteriorates faster and demands more frequent repairs. What could be a long-lasting surface becomes a recurring cost.
Why Liquid Rubber Paint Often Fails as a Waterproofing Solution
What Is Liquid Rubber Paint?
This common waterproofing product is often marketed as an affordable coating for cement. It’s applied to the surface, promising protection against leaks, damp, and cracks.
Why It’s Not Enough:
- Absorbed Into Cement: The porous nature of concrete means it absorbs these coatings instead of forming a full barrier.
- No Long-Term Durability: When applied to a cementitious substrate, most liquid rubber solutions degrade when exposed to harsh weather conditions as Liquid Rubber layers become thinner with time due to absorption.
Surface-Level Only: Liquid Rubber coatings rarely penetrate deeply or adapt well to substrate movement or joints, making them unreliable on cementitious roofs.
Ultimately, what seems like a cost-saving option often leads to premature deterioration, repairs, and additional product installation.
Choosing the Right Waterproofing System for Cement Surfaces
When evaluating waterproofing systems for concrete or cement substrates, consider the following factors:
- Weather Resistance: The system must endure a wide range of weather conditions and temperature shifts.
- Bonding Strength: It should attach securely to concrete.
Flexibility at Joints: Systems that move with the surface protect flooring, walls, and roofing against shifting. - Water Vapor Control: The best systems resist both liquid water and vapor.
Installation Suitability: Choose a solution designed for the specific surface.
The goal is long-lasting protection—not a temporary form of coverage.
Advanced Waterproofing Solutions That Work
What Is Liquid Rubber Paint?
This common waterproofing product is often marketed as an affordable coating for cement. It’s applied to the surface, promising protection against leaks, damp, and cracks.
At Rubber Roofs™, we rely on high-performance waterproofing products specifically formulated for concrete protection. Rubber Roofs™ is also the exclusive South African Köster agency, importer and installer of Köster TPO Waterproofing systems.
Köster TPO Membranes
TPO (Thermoplastic Polyolefin) is ideal for flat roofs and exposed flat cement surfaces. It’s:
- Heat-reflective and energy efficient
- UV stable for long-term durability
- Indestructible
- No PVC or Plastisizers
- Impermeable Barrier
- Enviro Friendly and Expert Application
- Resistant to extreme weather conditions and movement
- 20-Year Warranty on Product and Workmanship.
BulletProof Waterproofing System
BulletProof is our proprietary waterproofing solution for flat cementitious substrates. Providing superior protection against water infiltration and weathering, additionally creating an effective barrier over bitumen to help bitumen bleed. It:
- Seals from within to block moisture absorption
- Stays flexible under stress and temperature changes
- Self-Leveling
- Epoxy primer and specialized membrane
- Highly durable and Flexible
- Water Vapour Permeable and Impermeable Barrier
- With Rust Inhibitor.
Offers a long-lasting barrier for high-risk outdoor areas. - 10-Year Waterproofing Warranty on both Product and Workmanship.
These systems are installed with special attention to detail, delivering professional protection that holds up under pressure.
Final Thoughts: Cement Needs Long-Term Protection—Not Temporary Fixes
Cement, despite its strength, is vulnerable to moisture, dampness, and structural damage. Left untreated, even small cracks can lead to major issues across your building or construction project.
Don’t let water absorption, salt leaching, or mold compromise your investment. Liquid coatings, plastic paints, and DIY patch-ups are short-term fixes. Real protection comes from waterproofing systems designed to bond, breathe, and last.
Protect your cement surface the right way. Contact Rubber Roofs™ to determine the best waterproofing solution for your structure, substrate, and environment.