Water is great when it’s in the right place—like a pool or a bottle. But when it sneaks into spots like your basement, building joints, or concrete structures, it becomes a big problem. That’s where waterstops come in. They’re small but powerful tools used in construction to block water from leaking through joints in concrete. Whether it’s rain, underground moisture, or high water pressure, a waterstop works quietly in the background to protect your structure.
What Does a Waterstop Do?
A waterstop is like a shield. It’s placed in the joints of concrete structures to stop water from passing through. When two concrete slabs meet—like in tunnels, basements, foundations, or dams—there’s a joint. Water loves finding its way through these joints. If you don’t block it, it will leak, causing damage.
That’s where a waterstop plays its role. It creates a barrier inside the joint to stop water—even under hydrostatic pressure—from going through. It’s made of durable materials like PVC, rubber, or bentonite that don’t break down when wet. This makes it perfect for areas where water pressure is high, or where water is always present.
Where Do We Use Waterstops?
Waterstops are used anywhere water needs to be controlled in concrete joints. You can find them in:
- Basement walls and foundations
- Underground parking garages
- Water treatment plants
- Tunnels and dams
- Swimming pools
- Bridges and retaining walls
- Sewage and drainage systems
- Reservoirs and canals
Basically, if you’re building something that has concrete and will be exposed to water, you’ll probably need a waterstop. Without one, leaks can destroy the structural integrity over time.
Types of Waterstops You Should Know
There are many kinds of waterstops, but they all do the same basic job—blocking water from moving through joints. The main difference is the material and shape, which depends on where and how they’re used.
Let’s explore the most common types:
PVC Waterstop
PVC waterstops are the most widely used. They’re made of flexible plastic and can be bent, twisted, and installed easily. They come in different shapes like dumbbell or ribbed types, which help them fit tight in the concrete.
Key Benefits:
- Easy to install
- Works in expansion and construction joints
- Good for most general construction
- Resistant to corrosion and chemicals
PVC waterstop is perfect for residential and commercial buildings, underground tanks, and wastewater plants.
Rubber Waterstop
Rubber waterstops are heavy-duty. They are made from natural or synthetic rubber and are used in large construction projects like bridges, tunnels, and dams.
Key Benefits:
- Strong and durable
- High resistance to extreme temperatures
- Best for heavy load structures
- Great for long-term waterproofing
Rubber waterstops handle hydrostatic pressure better than PVC. They are great in areas with constant water flow, like sewage systems or large dams.
Bentonite Waterstop
This one is different. Bentonite waterstops are not installed in the joint during pouring. Instead, they swell when exposed to water, creating a tight seal.
Key Benefits:
- Easy to apply after concrete has hardened
- Swells to fill small gaps
- Ideal for repairs and post-construction sealing
- Eco-friendly and natural
These are often used in foundation walls, manholes, and precast concrete.
How to Install a Waterstop Easily
Installing a waterstop isn’t rocket science, but it does need to be done carefully. If installed wrong, it won’t do its job, and leaks will happen.
Here’s how to install a waterstop:
- Choose the right waterstop based on the project (PVC, rubber, or bentonite).
- Place it in the center of the joint where two concrete slabs will meet.
- If it’s a PVC or rubber type, make sure it’s secured using steel wires or clamps to avoid movement.
- Seal the ends properly to avoid any leakage paths.
- Pour the concrete in stages, keeping the waterstop centered in the joint.
- If using bentonite, apply it like a strip or paste on the hardened concrete before joining the next section.
Pro tip: Always make sure there are no gaps, cuts, or disconnections in the waterstop. Even a tiny gap can let water in.
Why Are Waterstops So Important?
You might be thinking, “It’s just a small strip of material—how important can it be?” The truth is, a waterstop is one of the most important parts of waterproofing a concrete structure.
Here’s why:
- Prevents water damage like mold, mildew, corrosion, and rot
- Extends the life of your structure
- Saves money on future repairs
- Protects interiors from leaks and flooding
- Keeps underground structures dry
- Helps in maintaining structural strength
Without a waterstop, even the best-designed building can fail due to water intrusion. That’s why building codes often require them in water-contacting structures.
Choosing the Right Waterstop
Not all waterstops are created equal. Picking the wrong one can lead to failure. Here’s how to make the right choice.
Look at Water Pressure
If your project involves high water pressure—like a dam or underground tank—go with a rubber waterstop. They’re built to handle tough conditions. For light to medium pressure, PVC or bentonite is fine.
Indoor or Outdoor Use
- Indoor projects like basements and foundations usually don’t face harsh weather, so PVC waterstops are ideal.
- Outdoor projects, especially those exposed to extreme weather, should use rubber for better durability.
What Are Waterstop Sizes and Shapes?
Waterstops come in many sizes and profiles. The right shape depends on the type of joint:
- Flat ribbed for construction joints
- Center bulb for expansion joints
- Dumbbell for high movement areas
- Swelling types for irregular or post-construction applications
Choosing the right profile, width, and thickness is essential to match the structure’s movement and water pressure.
Thoughts on Waterstops
Waterstops might be small, but they’re superheroes in construction. Most people never even see them, but their role is critical. Whether you’re building a high-rise, tunnel, or backyard pool, waterstops protect your investment. They’re like the silent bodyguards of your structure—working 24/7, stopping water before it causes damage.
The Bottom Line
To sum it up simply: If your building or structure involves concrete and water, you need a waterstop. It’s a low-cost, high-impact solution that keeps water where it belongs. From PVC waterstops for basements to rubber waterstops for dams and bentonite strips for post-install sealing, there’s a type for every job.
Choosing the right waterstop and installing it properly can save you thousands of dollars in repairs down the line. It’s a smart move for any builder, contractor, or homeowner. So next time you pour concrete near water, think waterstop—it’s the invisible hero you can’t afford to skip.
