Waterproofing Wisdom – Episode 10 Design and Detail

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Can you differentiate between Waterproofing design and Waterproofing detail? 

This episode emphasizes the distinction between the two and the importance of focusing on the larger design aspects before delving into specific details.

When we arrive at a situation and begin looking at zoomed-in detail, missing the bigger picture, it is easy to misunderstand the situation.

Too often in waterproofing, there is a drive to specify a product and immediately provide a ‘design’ (by which the industry often means a typical detail). This often misses greater considerations of hydrogeology, contamination and the wider site conditions.

The bigger picture must come first and we must resist the urge to provide detail until we’ve considered all the necessary fundamentals.

You can watch a 4 minute video here.

Waterproofing Wisdom Episode 10 – Design and Detail


Ben Hickman
Technical Director

Hello and welcome to Waterproofing Wisdom, Episode 10, where I’m going to be talking to you about waterproofing design and waterproofing detail. What is that? I’ll leave you with that for a minute.

This is a waterproofing detail from a CLW drawing, and you can see there’s a DPM there or EPDM, and there’s a drainage layer here with some tape on it, and there’s a waterproofing system here that’s been lapped, and then you’ve got a screed to falls. It’s detail, and you can see product specification and content like that. What you can’t see from there is what project it is, where in the building it is, what that’s supposed to do, anything like that. That’s a waterproofing detail.

This here is a drawing from a Stage 3 report, and it’s about waterproofing design. It’s our design philosophy document. I’ve intentionally zoomed out; it is a little bit pixelated on purpose. And on this project, there is a bigger section, so you can see this as a slice through the whole basement. Down the right-hand side, there’s the line of the earth-retaining system, and then up the left-hand side, you’ve got two options, but that there is your three-story deep basement there. For us, blue indicates watertight concrete; there’s a little bit more detail and some cavity drain content there. But it’s a bigger picture, and you can see where it fits on the site, that sort of content.

So, detail is small, a small picture, and design is the big picture. So, I wonder if you remember what that orange image is? It’s an orange! And in my experience, too much of the waterproofing industry is looking way too close, and so you can’t see the wood from the trees. A lot of the industry is pushed and governed by product suppliers, and what do they want to do? They want to put their products into the building. And so, without looking at the big picture, without properly thinking through the site and what’s in the ground and hydrogeology and the contamination, they want my product in there, and so it goes to small fine detail too quickly.

I’ve just finished a massive expert witness report for a job elsewhere in the world, and the waterproofing consultants did a phenomenal job on the detail. They’ve done hundreds of details and they’ve gone to town on all these different products and where they go and all of that stuff. But they completely missed the waterproofing design, the big picture. They didn’t think through what’s in the ground, how dry do we need this building to be, what is going to be inside there, therefore how do we make it dry enough. It resulted in a fairly catastrophic error, and there’s going to be a big financial pay out by somebody.

I guess I’m just appealing to the waterproofing industry in general. If you’re looking at the waterproofing design, look at design, make that big picture. In my opinion, that should come with the waterproofing design report that explains your full design rationale. It should show your full risk assessment: what is the water table, what’s in the ground, what’s the hydrogeology, how dry do you need it to be, and why? Have I thought through repairability, maintainability, buildability and all of that content? That’s design. If you’re looking at a picture that’s got a product reference on it, that’s probably detail. And I hope that that comes after design.

If I show you this orange picture here and then show you the zoom-in, you know what you’re looking at. If you do it the other way around, you can go awry. And so, there’s my little piece of waterproofing wisdom.

Thank you for watching.

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