How To Prevent Basement Waterproofing Failures

June 2025 Newsletter

Basement waterproofing failures cost the UK construction industry millions of pounds every year—not just in repairs, but in project delays, reputational damage, and client dissatisfaction. The most frustrating part? These failures are entirely preventable.

At MacLennan, we’ve spent decades refining our approach to waterproofing design, installation, and maintenance. In this post, we’ll explain how we prevent failures before they happen—and why our systems are trusted across the UK and beyond.

KC4 Lots Road Case Study road lift before after

KC4 KC4 Lots Road Case Study Road Case Study 17

May Newlsetter - 9 Partridge Walk - 10.05.2024 JH

✅ It All Starts with Smart Design

Most waterproofing failures can be traced back to one root cause: poor design. At MacLennan, we believe that good design is the foundation of waterproofing success. But we’re not just talking about detailing—we mean integrating the installation process, maintenance strategy, and repairability into the design from day one.

The British Standard and all major codes of practice are clear: waterproofing systems must be designed with repair and maintenance in mind. Yet, many systems are installed without any consideration for how they’ll be accessed or serviced once finishes are in place.

🧱 Why Type C Systems Are the Gold Standard

If your basement includes finishes, internal walls, or linings, then only a Type C cavity drain system can provide the level of repairability required for long-term performance.

Unlike other systems, Type C solutions are designed to manage water ingress by directing it to a controlled drainage system. But even these systems can fail—if they’re not properly maintained.

🔍 Inspection & Servicing: The MacLennan Difference

Most service providers focus on pump maintenance, but the real Achilles heel of a cavity drain system is the drainage channel. If this becomes blocked or compromised, the entire system is at risk. At MacLennan, we’ve solved this with:

We design and manufacture our own inspection ports, allowing directional camera access for full visibility.
We commission and inspect the system after finishes are installed—when many issues first appear.
We provide ongoing servicing through our dedicated in-house team, ensuring long-term performance.

📡 Remote Monitoring & Superyacht-Grade Reliability

We’ve taken it a step further with remote monitoring technology built into our systems. This allows us to track performance in real time and alert clients to potential issues before they become problems.

And when it comes to power reliability, we use state-of-the-art battery backups and inverters—the same systems trusted on ocean-going superyachts. These can even be upgraded to power essential services during outages.

🛠️ Servicing Is Not Optional—It’s Essential

You wouldn’t buy a car and never service it. A waterproofing system is no different. Regular maintenance is the key to preventing failures, and it should be built into the design from the start.

At MacLennan, we don’t just install systems—we design them for life.

💬 Want to Learn More?

We’re passionate about helping clients avoid costly waterproofing failures. If you’re planning a basement project or want to ensure your current system is protected for the long haul, get in touch with our team.

Contact us

Asbestos encapsulation and waterproofing

MacLennan have been engaged to waterproof a WW2 bunker in the beautiful Dorset. The issue was that the existing waterproofing contained Asbestos which would be very difficult to remove.
Maclennan specified a sprayed foam encapsulation, rendering the Asbestos completely safe. The spray foam was then finished with spray-applied Polyurea.

The result is a completely safe and waterproof structure ready to be reburied and converted into holiday lets with stunning views out to sea.
All work guaranteed and designed on MacLennan's 10 million PI for waterproofing.

Back to work, back to training!

Today some of our staff were retrained in First aid and we rolled out our online training program, starting with Health & Safety. We are hoping for a respite from lockdown by the spring, once Vaccinations have protected the vulnerable and alleviated the pressure on hospitals, but we are planning for Covid awareness and precaution for the long term, just in case it is the new normal. Training is one of the key principles for success so we have put all of our ongoing training online apart from the first aid ( you cannot kiss a virtual dummy ) and the practical training that requires hands-on learning like spraying waterproof coatings and applying products. Our staff are trained, Covid aware and we have the capacity for new projects of any size, which we can and will deliver promptly and professionally even in these difficult times.

Our MD Ian MacLennan is on the committee re-writing BS8102 Code of practice

MacLennan’s managing director has been invited to help re-write the BS8102 Code of practice for protection of below ground structures against water from the ground.

Why does this committee need consultant/contractors?

It is our site experience of hundreds of basement waterproofing installations per year and hundreds of investigations of sites, failures, issues that feed the industry with ideas for new products and new processes.

As a company that helps investigate it’s own and others mistakes in a specialist industry, to help come up with robust and sometimes unique ways to solve complex problems we are constantly learning, sharing and discussing these in-depth challenges & solutions to interesting problems. It’s what built our high-class team of specialists that can guide, advise and inform clients with a depth of knowledge that you cannot learn without our experience.

We provide hundreds of basement waterproofing solutions every year and the majority go without a hiccup but we’d be naive and in denial, if we weren’t aware that we work in the construction industry that is constantly evolving and has unique challenges each and every day. But this is also what allows us to be innovative and helpful in efficiently overcoming these stumbling blocks without holding up our client’s programs or compromising the watertight outcome. Access to our specialist skills is key when you are against the clock to deliver a project on time but also need to get the right detailing so you have no area of weakness in your complete waterproofing solution.

All this experience goes into every job we design each and every day, and this is what our MD’s personal current contribution to the current & new BS:8102 advisory committee brings. As you cannot underestimate the value of a genuine specialist with the in-depth knowledge and experience to solve any problem that may come up, as well as having the capability to design & install you a waterproofing solution that is fully fit for purpose. Simplicity is often the key feature of someone at the top of their game as they see clearly what’s needed and quickly eliminate features that have limited value and come with higher risk.

That’s why a company that stands by its solution with a genuine guarantee for workmanship and the design is priceless in a high-risk industry as they are there to help remove your exposure to failure as they will always be there to help at every stage of the process, even after it’s completion. As it pays to never be complacent, always think through a design thoroughly, consider the clients budget to deliver value but without compromise, it’s buildability, to have the capability to communicate everything clearly and informatively. As to be a specialist consultant whether as an individual or a company comes with a responsibility that goes beyond a basic qualification but also covers the experience of the whole team that goes into delivering a full sub-contract package of works.

Design meeting at MacLennan headquarters

Waterproofing, Better by Design.

Ian Scoggins CSSW

I have worked in the construction industry for 28 years and have been specialist waterproofing surveyor for 12 years, my time as a waterproofing specialist has given me a rounded experience of the industry.

During that time in the industry, I have seen projects that have gone very well and some not so great.

Based on my personal experiences, I have come to realise that its early engagement and collaboration with the overall design team that delivers the best results. By everyone investing time in early engagement, I find that designs can often be simplified as sitting around a table and everyone giving their input can often take out expensive complexity and give a much better overall solution, that ultimately benefits the end client.

This only works when the correct sub-contractors are engaged on project early, so they are associated with the project from day one, one thing that sets us apart from manufacturers offering technical support is that we are involved in projects on-site every day and know the practical solutions to problems that aren’t always evident when looking at a drawing.

When it comes to high-risk elements like the basements and waterproofing, going out for multiple tenders and the lowest bidder often leaves you with skills and scope gaps as there is a clear lack of ownership. It can then become about delivering a solution to a budget, rather than a simple but effective solution that works with all the other key partners on the project in mind that’s actually deliverable on-site.

This doesn’t mean the client shouldn’t benchmark the competition and capabilities, as I live in the real world and want to offer real value for money to my clients but I want to do this without them un-intentionally building in unnecessary risk by accident by being insightful and helpful early on. It’s what falls between the cracks where the real risks sit (no pun intended) that really sets out your specialist subcontractor as part of a collaborative team that makes all the difference.

"My role is as much about sleeping well at night, as it is about waterproofing."

As myself, my MD, our insurance company, the main contractor and my end client all want to never ever worry about what the waterproofing is doing as it’s a hidden system in their beautiful property that just does what its supposed to. Its why our company takes full design and solution responsibility and hold genuine guarantees as we offer our clients leak free basements from a waterproofing perspective rather than material warranties.