Waterproofing Wisdom – Episode 04 Construction Sequence

Waterproofing Wisdom is our monthly snippet of thoughts/lessons learned/news. You can sign up here.


Welcome to this episode of “Waterproofing Wisdom” which discusses the construction sequence of a basement.

In this episode we look at the construction sequence of a basement up to ground level and recognise:
1. Waterproofing starts early so we need early waterproofing engagement, and
2. Waterproofing doesn’t easily fit into one of the bigger packages of work and main contractors, therefore we need to think that through thoroughly.

You can watch a 3 min video here.


Ben Hickman
Technical Director


Hello and welcome to waterproofing wisdom episode four my name is Ben and I am the Technical Director at CLW and Waterproofing Wisdom.

This is my monthly opportunity to share with you something of interest that has gone on this past month. So I’m going to take some content from a presentation that I’m doing next month for the International Structural Waterproofing Conference and share with you a little animation but It’s around podiums and capping beams.

Capping beams I guess in particular so, on the left here we have a row of secant piles that aren’t great and the red material is a waterproofing gas proofing liquid applied system and over that will be a capping beam and then to the top right that image is the excavated basement here is a an animation of a sort of construction sequence so first the red there represents the waterproofing it goes on to the secant piles and it needs to go on before the capping beam gets cast so it’s pre-applied Type A waterproofing once that’s all in you can excavate the site put in the blinding and put in the pre-applied waterproofing to the slab and the walls again the red represents the waterproofing there and then you could cast the basement slab and the liner wall once that’s all and you could cast your podium deck and following that you could do the inner leaf of the ground floor wall and then you need to put in waterproofing before you do the outer leaf of the ground floor wall and we would also want to put in a drainage layer and land drain followed by the landscaping and hard landscaping.

So why am I showing you all that, I guess the point I want to labour is often we work for construction companies who want to start on site and often the design isn’t quite done but they want to start on site and we’ll say how soon you need the waterproofing done and they’ll say well piling starts in two weeks and i just want to highlight that if you haven’t got your waterproofing design in place before your piling that could lead to significant difficulty you might have designed out some options the other thing I wanted to point out is that waterproofing doesn’t fit nicely and neatly into a single package so you’ll see that animation that waterproofing needs to go in with the piling under your piling under your capping beam it also needs to go in under your concrete slab and liner wall but it also needs to go in just before brickwork and just after brickwork and it also needs the land drain so it’s in with the civils and then it also needs all of your EPDM on your fenestration to terminate onto your waterproofing so waterproofing sort of weaves its way through a lot of different packages and that needs a lot of consideration as well so I’m driving it number one a point a waterproofing designer early RIBA Stage Two or right beginning RIBA Stage Three and number two just be very careful about what package you’re trying to fit waterproofing into because it might not neatly fit so that’s just briefly what I wanted to share.

If you want to talk to us about basement waterproofing or waterproofing design or anything like that, please get in touch

Thank you very much

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