Welcome to Episode 18 of the Waterproofing Wisdom series, content that will be especially relevant to Project Managers, Architects and Engineers.
You can watch the short 5-minute video below, or read on for the highlights.
Introduction
When it comes to protecting below-ground structures from water ingress, there’s a simple but often overlooked truth: waterproofing design should only be undertaken by a waterproofing specialist.
This isn’t just a recommendation—it’s a principle outlined in BS 8102: the Code of Practice for Protection of Below Ground Structures Against Water Ingress.
The standard is clear in stating:
“A waterproofing specialist should be appointed as part of the design team.”
Let’s break that down.
Waterproofing Wisdom
Why “Appointed” Matters
The word appointed is not a throwaway term. It carries contractual weight. It means the waterproofing design must not be treated as free advice from a supplier, or an afterthought in a design-build contract.
When you formally appoint a waterproofing specialist, there’s a clear line of responsibility and recourse should the design prove inadequate. Without that appointment, you may find yourself without proper support when issues arise.
Who counts as a Waterproofing Specialist?
By definition, a specialist is someone who focuses primarily on one field. So while your architect or structural engineer is likely an expert in their own discipline, that doesn’t automatically make them a waterproofing specialist.
In fact, according to the professional codes of conduct from the Institution of Structural Engineers (IStructE), the Royal Institute of British Architects (RIBA), and the Institution of Civil Engineers (ICE), professionals are obligated to only undertake work for which they are competent. This means:
- Architects should only offer waterproofing design services if they are trained and experienced in this specific field.
- Engineers must not stray into waterproofing design unless they have proven competence.
Yet, in our experience at CLW, we often see waterproofing design handled by architects and engineers—especially in early design stages such as RIBA Stage 2 or 3. This is typically done with good intentions, offering early advice to help the client, but it can become problematic further down the line.
The Hidden Risks of DIY Waterproofing Design
Waterproofing design is complex, and many of its crucial components are “unknown unknowns” for professionals outside of the specialty. Even on large, high-profile projects, we’ve seen important aspects of waterproofing left out of the design conversation entirely.
Take, for example, our Waterproofing Design Responsibility Matrix, which outlines key decisions and responsibilities across the project timeline. Without specialist input, many of these responsibilities fall through the cracks—often because architects and engineers aren’t even aware they exist.
This is more than a missed detail. It’s a risk to the entire structure.
NHBC and Industry Expectations
Bodies like the NHBC, who insure and approve structures with basements, are especially stringent about waterproofing. They require that the waterproofing design be produced by a suitably qualified, appointed specialist.
Their message echoes BS 8102: design responsibilities must be clearly defined and assigned to the right professional from the outset.
Closing Comments
In short, waterproofing design is not a box to tick, or a set of products to specify without deep understanding. It’s a specialist discipline that requires dedicated expertise.
At CLW, we’re passionate about getting this right—not just for compliance, but to protect your project’s performance and longevity. If you’re designing a basement or planning a below-ground structure, make sure a qualified waterproofing specialist is appointed early in the process.
We’d be happy to help.
Many thanks,
Ben Hickman
Hello, and welcome to another episode of Waterproofing Wisdom. My name is Ben, I’m the Technical Director of CLW, and this time I wanted to talk about – “Who should do waterproofing design?”
This is from BS 8102, which is the the code of practice for protection of below ground structures against water ingress.
And I’ve highlighted this part, that says “a waterproofing specialist should be appointed as part of the design team”.
So, I think it’s quite clear that a waterproofing specialist should be doing the waterproofing design.
And I also wanted to highlight this point, which is ‘appointed’, which is quite, a kind of, contractual word, but I think what that means, is that really, the person doing the waterproofing design should not be a free piece of advice from a supplier.
There does need to be a contractual appointment, and with that comes appropriate lines of recourse should that advice be bad.
So a Waterproofing Specialist should do the waterproofing design on a basement.
What is a specialist?
Well, a specialist is somebody who concentrates primarily on a specific thing – so because of that, it’s unlikely that your Architect or Engineer is a Waterproofing Specialist, because it’s much more likely that they are a Structural Engineer, or an Architect.
So I think that’s important, and I also think that this is important.
So this is the code of professional conduct from the Institution of Structural Engineers, and that says if you’re a Structural Engineer, you should only perform services in the things that you’re competent in.
Similarly for members of RIBA, practices must be competent to undertake the services being offered.
And then similarly ICE again, professional code of conduct says members shall only undertake work that they’re competent to do.
However, in our experience, a lot of waterproofing design is actually undertaken by architects and engineers and a lot of that’s early in the design process and maybe Riba Stage 2 or 3.
A lot of that’s undertaken as a genuine goodwill looking to help the client, and you know, if if we just spell out a bit of waterproof concrete here and a bit of a membrane there, and ultimately it’s going to be a design and build contract, and that later design input can come from another professional later down the road.
That seems to be the thinking amongst a lot of Architects and Engineers, and I think that’s problematic.
Entities like NHBC, who would insure buildings with basements, they seem really hot on this, that actually the waterproofing design must be done by a suitably qualified person, and again, they point out this needs to be an appointed Waterproofing Specialist.
So this is the kind of – it’s work in progress – but this is a design responsibility matrix that we would use to try and spell out between Riba Stages 2 and well, Gateway 2, to conflate two different things.
These are some of the different waterproofing design things that need to come together, and unfortunately for many, that’s an ‘unknown unknown’.
So a lot of Architects and Engineers, although they know lots about architecture and engineering, don’t realise that there are a whole bunch of components to the waterproofing design development that they aren’t even aware of.
So in our experience, the design responsibility matrix in the mind of a design team, even on major schemes, loses a whole bunch of what’s very important for structural waterproofing design.
And that’s why it’s very important to appoint, again, ‘appoint’ a competent structural waterproofing design specialist.
And obviously we’d like that to be us!
I hope that’s helpful, I hope that points out an area of concern, and if there’s anything we can do to help you, please get in touch.