Concrete is often described as “watertight”. But in reality, concrete alone is rarely enough to guarantee long-term waterproofing performance.
In civil engineering projects, structures are exposed to groundwater pressure, movement, construction joints, and natural cracking over time. Even with good design and workmanship, water will always look for the weakest point.
That’s why effective waterproofing isn’t about relying on a single material or hoping the concrete performs perfectly. It’s about creating a coordinated Type B waterproofing strategy designed around how concrete behaves in the real world.
At Premcrete, we believe waterproofing should be engineered into the structure from the very beginning, not treated as an afterthought once the concrete has been poured.
Waterproofing Starts at the Design Stage
Before concrete ever reaches the site, waterproofing performance is already being influenced by structural design.
Under BS 8102:2022, a 0.2mm crack width is recognised as a watertight concrete design. Achieving this depends heavily on the structural engineer’s reinforcement detailing and crack width calculations.
But design alone isn’t enough.
The reinforcement must then be assembled correctly on-site by formwork contractors and steelfixers to ensure the structure performs as intended. If reinforcement placement is inconsistent or poorly installed, crack control performance can quickly be compromised.
Good Concrete Practice Still Matters
Even the best waterproofing strategy will struggle if the concrete itself is poorly installed.
Concrete compaction plays a critical role in waterproofing performance. Poor compaction can leave voids and air pockets within the structure, creating direct pathways for water to make its way in.
The concrete mix itself is equally important.
Water-to-cement ratios must be carefully controlled to reduce permeability and maintain durability over time.
In short, waterproof concrete is never achieved through one element alone. It relies on design, workmanship, and material performance, all working together as part of a coordinated waterproofing strategy.
Why Crack Width Design on Its Own Still Isn't Enough
Even if all of these measures are carried out correctly, very few contractors or manufacturers will provide a waterproofing warranty based on a concrete crack width design alone.
Why?
Because a structural engineer rarely takes full design responsibility for the structure from a waterproofing perspective. And building warranty providers are looking for someone to supply a warranty.
So, if the engineer won't provide a warranty, or the concrete supplier, the rebar provider or the RC frame contractor, then this is where waterproofing material manufacturers come in.
That’s where waterproof concrete additives become critical.
How Hydrocrete Enhances Type B Waterproofing
At Premcrete, we have developed Hydrocrete to enhance Type B integral waterproofing protection within concrete structures.
Built on Dual-AC Technology, Hydrocrete combines crystalline waterproofing technology with a hydrophobic pore-blocking component to create a more advanced waterproof concrete admixture.
The first stage of protection comes from the hydrophobic pore-blocking technology, which helps reduce water absorption within the concrete matrix itself. This immediately limits the movement of water through the structure and reduces permeability from the outset.
The second phase activates upon contact with water. Hydrocrete produces nano-scale crystals within the concrete’s micro-capillaries, helping block water pathways and restrict moisture migration throughout the structure.
Unlike traditional waterproofing approaches, these crystals remain active for the lifetime of the concrete, providing ongoing protection long after installation.
Together, these technologies help:
- Reduce concrete permeability
- Provide two-fold protection
- Increase concrete corrosion resistance
- Limit water ingress
- Improve long-term waterproofing performance
Hydrocrete is supplied in powder form within pre-weighed water-soluble bags, allowing efficient addition directly into the concrete at the batching plant.
The result is a Type B waterproofing system designed not only for compliance, but for long-term structural resilience.
Waterproof Concrete Is Only Part of the Story
Even if the concrete itself is waterproof, structures still contain vulnerable areas. Think construction joints, kicker joints and movement joints.
These remain some of the highest-risk areas for water ingress.
And that’s why joint waterproofing systems are essential within any Type B waterproofing strategy.
Understanding waterbar technologies
Different joint conditions require different waterproofing approaches.
Hydrophilic waterbars, such as Hydrostop BR, help to seal construction and expansion joints and prevent the passage of water through the concrete.
Alternative systems, such as Cemflex VB, use a galvanised steel plate, which is crystalline-coated to create an active waterproofing barrier directly within the joint itself. This technology can be effectively installed before the concrete pour or directly into fresh concrete, enhancing the flexibility of construction schedules.
Furthermore, movement and expansion joints require a robust waterproofing detail. Often found on podium decks, these joints demand specialist products like Exofoam and Preflex PU placed in the joint, plus a waterproofing bandage such as Hydroband HP with a steel plate.
This layered approach is what creates a reliable Type B waterproofing system, not reliance on a single product or technology.
A Complete Type B Waterproofing Strategy
Under BS 8102, these systems collectively form what is known as Type B integral protection.
But successful Type B waterproofing is never about simply adding an admixture into concrete.
It requires:
- Controlled crack width design
- Correct reinforcement installation
- Proper concrete compaction
- Suitable concrete mix design
- Waterproof concrete additive technology
- Effective joint waterproofing systems
At Premcrete, we take a full-system approach to waterproofing design.
And as a British manufacturer working directly with contractors, engineers, and designers, we develop systems around the realities of civil engineering construction, not just laboratory conditions.
That means our solutions are designed for:
- Long-term durability
- Real site conditions
- Reliable installation
- Compliance with BS 8102:2022
The Bottom Line
Concrete alone is not waterproof.
Long-term waterproofing performance comes from combining structural design, workmanship, admixture technology, and joint protection into one coordinated Type B waterproofing strategy.
At Premcrete, that’s exactly what we develop our systems to achieve.
Real structures. Real conditions. Real performance.
If you’re designing or delivering a civil engineering project requiring Type B waterproofing protection, our technical team can help you specify a system built for long-term performance and compliance.
Arrange a 15–30 minute technical design workshop with Premcrete today.
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