Concrete is a strong and versatile material, but it’s not immune to water damage. Waterproofing helps maintain its structural integrity by protecting surfaces from moisture. Whether you’re working on a basement floor, driveway, or patio, sealing concrete prevents issues like cracks, spalling, and general wear and tear. In this guide, we’ll take you through everything you need to know about waterproofing concrete, from the basics to how to apply the right sealers.
DIY Concrete Waterproofing Methods
Several methods exist to waterproof concrete, each with its own advantages. The waterproofing method you choose depends on your needs and the concrete’s location. Below are common methods explained in detail to help you make an informed choice.
Cementitious Waterproofing
Cementitious waterproofing is often used in wet areas such as bathrooms. This method involves applying a mixture of sand, cement, and water-resistant additives to the concrete surface. It’s an affordable option suitable for positive and negative side waterproofing. Cementitious products are simple to apply and favored for their ease of use, requiring only basic tools—usually a brush or spray—to achieve a seal.
Liquid Waterproofing Membrane
A liquid waterproofing membrane is a fluid coating that forms a seamless, elastic membrane when cured. It proves ideal for areas with complex shapes or many penetrations, such as sloped rooftops or decorative outdoor areas. Because of its fluid nature, it works well on any surface it coats. Once cured, it remains flexible and accommodates slight structural movements, making it an excellent option for structures subject to changing conditions.
Bituminous Waterproofing
This method uses a tar-like substance to create a water-resistant layer. It is effective for below-grade applications like basements but is unsuitable for exposed surfaces due to its appearance. Bituminous coatings provide robust protection against groundwater infiltration. It works well in commercial or industrial establishments when combined with additional protective barriers.
Polyurethane Waterproofing
Polyurethane waterproofing is a versatile option applied as a liquid or spray. Polyurethane waterproofing offers elasticity and works well for areas subject to movement or settling. Its long-lasting and highly adhesive properties make it ideal for heavy-duty applications. Its resistant nature to chemicals adds extra durability in industrial environments.
How to Waterproof Concrete
Waterproofing concrete is a manageable project that requires guidance and patience. Follow these steps for a successful application:
Step 1: Prepare the Concrete Surface
The first and most crucial step for a successful project involves preparing the concrete to accept the waterproofing. This means making sure the surface stays clean and dry.
A clean surface is necessary because waterproofing also acts as a sealer. Any dirt, insects, or debris left behind will get sealed in, becoming part of the surface once the waterproofing cures. Removing these beforehand saves you from having to scrape them off later.
Cleaning is vital because stains or blemishes block the sealer from bonding to the concrete. If the waterproofing doesn’t adhere properly, it will likely flake off over time. At the very least, sweep the surface thoroughly. For the best results, pressure wash, especially for older concrete with years of buildup. The cleaner the surface, the better the waterproofing will perform.
Step 2: Choose the Right Waterproofing Product
Choose a waterproofing product tailored to your concrete application. Consider important factors like the concrete’s location— indoors or outdoors—the level of water exposure it will face and the desired finish, such as matte, glossy, or textured. Review product labels thoroughly, as they provide information about compatibility with your concrete surface and the surrounding environment.
Step 3: Apply the Waterproofing Sealer
The application process for waterproofing concrete varies by manufacturer, but it involves spraying, brushing, or rolling the product onto the surface. Many waterproofing products include additives that influence sheen, texture, or color. For example, manufacturers in regions with harsh winters include sand or other abrasive materials to improve traction and reduce the risk of slippery ice. Additives also tint the product to enhance the appearance of the concrete. Full coverage of the sealer proves essential because even a small unsealed spot can let water in and cause cracking.
Professionals start by pouring the waterproofing material onto the surface and spreading it according to the instructions. Most products perform best when applied in several thin coats rather than one or two thick layers. Use tools such as push brooms, paintbrushes, or paint rollers to achieve the recommended thickness and uniform coverage.
After each coat, the waterproofing dries to the touch before the next layer gets applied. It’s difficult to apply too much waterproofing, so focus on achieving full coverage while keeping costs in check. A properly applied sealer provides lasting protection.
Step 4: Allow Proper Curing Time
Patience is necessary when waterproofing concrete. Give the sealer plenty of time to cure before you let water or foot traffic touch it. Curing times vary by product but range from 24 to 72 hours. Correct curing is needed to achieve maximum performance from your waterproofing effort.
Step 5: Test the Waterproofing
Once cured, test the waterproofing by pouring water on the surface. A potent waterproofing product causes water to bead and evaporate without penetrating the concrete. If water beads unevenly or doesn’t bead in certain areas, the waterproofing layer is too thin and needs reapplication.
Many waterproofing products require reapplication every few years, depending on the level of wear and tear the surface endures. Available finishes range from completely flat to semi-gloss, so consider the intended use and appearance of the concrete. Adding sand or other abrasive materials during the application process improves traction and reduces slip hazards for slippery surfaces.
Why Concrete Needs Waterproofing
Despite its strength, concrete remains vulnerable to water damage. Here’s why waterproofing proves crucial:
- Prevents water absorption and ice formation.
- Extends the concrete’s useful life.
- Maintains structural integrity.
- Reduces maintenance costs over time.
Waterproofing creates a barrier that stops moisture from penetrating the concrete surface—avoiding the damaging effects of water infiltration and freeze-thaw cycles. This barrier prevents common issues such as spalling, where water entry causes the surface to flake away, creating a safety hazard and an unsightly appearance.
Benefits of Waterproofing Concrete
The benefits of waterproofing concrete make it a valuable investment. It protects surfaces from water damage and freezing. Proper waterproofing improves the appearance of concrete, helping it maintain a like-new finish while making cleaning and maintenance easier. Waterproofing prevents efflorescence, the unsightly white, powdery deposits found on inadequately sealed surfaces. These advantages help make concrete structures stronger.
By sealing the concrete surface, waterproofing adds a layer of insulation against wear and tear. This protection reduces unexpected repair costs and increases curb appeal—protecting your investments.
Maintaining Waterproofed Concrete
Maintain your waterproofed concrete surfaces with regular cleaning. This helps prevent dirt and debris buildup, keeping the surface in good condition. Reapply the sealer every 2–5 years, depending on the level of wear it receives and environmental exposure. Promptly address any damage or cracks to prevent water infiltration that compromises the concrete’s integrity.
Common Mistakes to Avoid When Waterproofing Concrete
There are common mistakes to avoid to achieve better waterproofing results. Applying sealer to damp or dirty surfaces results in poor adhesion, and selecting the wrong type of sealer leads to insufficient protection. Overly thick coats cause improper curing and leave an uneven finish. It is important to address moisture issues, like leaks, before sealing to strengthen the process. Removing these pitfalls creates a reliable moisture barrier for your concrete.
When To Call a Professional
Many concrete waterproofing projects are DIY-friendly, but some call for professional expertise. Large-scale commercial applications require specialized tools and techniques, while severe water damage or structural issues involve safety concerns. Complex drainage issues need customized solutions, while below-grade foundations or detailed architecture require professional expertise.
If you are uncertain about managing your waterproofing project, consult a professional contractor for guidance.
Final Thoughts About Waterproofing Concrete
Waterproofing concrete protects and preserves your concrete structures. Whether selecting a DIY approach or seeking professional help, waterproofing pays off in the long run through reduced maintenance costs and longer-lasting concrete.
While waterproofing remains important, it’s not a one-time solution. Regular maintenance and periodic reapplication of sealers will keep your concrete surfaces protected.
