This interview with MVRDV director Gideon Maasland was originally recorded as a contribution to a May 2022 feature on Valley for The Architect’s Newspaper. It was conducted and edited by MVRDV editor Rory Stott. 

Rory Stott: Ok, we’re here to talk about Valley, and specifically we’re here to talk about the façades, the details, and all that technical stuff. Tell me a little about that aspect of the building.

Gideon Maasland: Valley was a project where there was endless testing and adjustments to almost every part of the façade, to make sure everything was optimised. You see the render, and you think oh, that's a very complex building. But even for us, throughout the process, everybody was saying “yeah, it was so much more complex than we ever thought”. Every apartment is different, which is super nice, but it’s a lot of work.

What’s easy to forget is that if I make one terrace smaller, maybe another person’s kitchen has a hole, right? It's not so simple to keep endlessly changing the shapes. It has an effect on the floor you reshape, the floor above because it has a terrace and maybe now that is not usable anymore, and on the floor below because what was inside now has a hole.

RS: How would you say that impacted the process of realising the details?

GM: The three-dimensionality was a big part of it. We finished all the details in the detail design phase, and then Inbo took over, and the contractor came. Many times after that we had somebody that adjusted the 2-D details say something like, “yeah, we pushed this up slightly so the waterproofing is better.”

We always had to respond “ok, how does it turn the corner?”

“What do you mean, turn the corner?”

“Well, because this is connected to something else, right?”

RS: And there are a lot of corners in Valley!

GM: That's exactly the point. We could never make this if we weren’t able to control the details. I still remember: the terrace floor is 173 millimetres above floor level, and you cannot make it 174 and you cannot make it 172. It is 173. It's really precise like that, and it’s actually built like that, even though many people tried to change it. If you have less, you have too little height for the waterproofing, but if you make it higher, you do not have the 2.4 metres of free height to call the terrace an outside space.

The project concept includes two different types of façade: the exterior walls of sheer mirrored glass, and the jagged stone terraces inside. Image © Ossip van Duivenbode

RS: Why did the design team opt for the material palette mixing glass and stone façades? 

GM: Yeah, that’s an architectural question that generally speaking we’ve answered many times, in terms of the overall project concept. But in addition to the general answer, it really has an in-depth answer, that is more specific to the issue of detailing.

So, think back to the start of the design, when we had only very basic renders. What did we do? There’s the glass, there’s the natural stone. How do they meet? In a perfect edge, a point that goes to zero.

RS: Because they’re rendered in a programme where things have zero thickness.

GM: Exactly. So that's not gonna work. First of all, because the stone façade meets the glass at a million different angles, and secondly, indeed, it has a thickness.

Making that argument upset a lot of people on the design team, and it was completely out of the question initially. People were saying, “no, no – the concept is like an apple”, where it has a smooth, wafer-thin outside skin and then you take a bite and see the softer inner parts. The problem is firstly, you can never solve it like that. But even if you somehow did find a way, the tolerances are zero, so you would never get it built nicely. I had to convince the rest of the team the week afterwards by saying, “hey listen, you want the apple concept, right? Problem is, we have the material of an orange. We need to make an orange.” Then it was okay.

So that's why on Valley you see this edge, and it’s actually quite beautiful, like a mark outlining the edges of the stone. Then you can connect the stone from the back of the glass, and you can accommodate all of these different angles.

Solving details like this is a conceptual issue. If you don't know how to detail, you will never solve them, and then your concept is weakened simply because you couldn't make a detail.

Those crucial conceptual details can go on to have another life afterwards. With Valley, we know the kinds of things people want to know, which is how we made the planters for example. Other architects outside of MVRDV want to see that, but I also get that question a lot from architects at MVRDV asking “how did you do this?” I think that's brilliant. It's very nice to work on this puzzle, and I think for the office it’s also valuable.

A detail drawing of a planter in Valley

RS: Is there a standard dimension to the glazed and masonry elements?

GM: Yes. The glass is super rigid, It's an 8.1-metre grid and it's divided so everything is 2.025 metres. Everything, we never cheat. It's always exactly that.

RS: So even where you have the steps out on the edge, in response to the jagged inner façade, it's always a step of exactly 2.025 metres?

GM: Yeah. Then there’s the natural stone tiles. At first in the tender documents we put the regular brick pattern, like a running bond. That was because at that point, we had only drawn a partial sample of the façade. In the partial it looked okay, but we forgot the 3-D step. So what happens is that when you fit it nicely on one end, at the other end of the run you might end up with a tiny sliver of stone, which looks ugly and it cannot be done. You cannot hang such a thin piece of stone. So we started to discuss with the contractor to say, “sorry, we need to have an irregular pattern”. Of course he went completely nuts – it’s more expensive, it's already irregular, blah blah blah.

RS: Because for the contractor they want something completely regular, every piece is the same size, and then you get to the end and you cut a piece and that fits in, right?

GM: Exactly. The regular approach, where you simply have a truckload of regular tiles and then you cut one when you end up at the framework, they think it’s super easy. So we did comparisons. In the end we said, if you do the irregular pattern, you will have more standard tiles, and less cutting. They were kind of shocked… “more standard tiles?” That was interesting.

Then we started to discuss with the natural stone supplier, Kolen Natuursteen, to ask them how big these tiles can be. Because every tile has four anchors, whether it’s big or small, always four. If you do more it breaks, if you do fewer it falls off. The labour – the money – is in installing the anchors. So we went from a repeating pattern of 800 by 400 millimetres to a mix of sizes where the biggest ones were double the size. That generated a bit of positive energy on the contractor’s side.

Then, MVRDV NEXT came in with a computer script because the contractor was a bit scared. How could they possibly control this? We told them we're going to draw everything, so you will get a Revit file that has the names and numbers for every single tile, so you have everything you need. Which was hell, we worked on it for a year, but in that way, with the parametric modelling, we could make that work. I think we can make projects like Valley simply because of the scripting and the technology that we now have in-house.

RS: Okay though, for the people like me who haven’t spent much time on a complex construction site: say I’m a builder, what do I get? Do I get a big sheet and every tile is numbered and I have to figure out, “this one goes here, this one goes here”?

GM: In the end, everything was numbered – because yeah, you cannot send a truckload of tiles and then say “you figure out which one goes where” because that's like a 40,000-piece jigsaw puzzle.

It was organised in such a way that each crate can be put on the right floor in the right position, right next to where the tiles inside will be installed. We numbered them according to the contractor’s input, so they say they want a certain numbering system, and NEXT made that possible. In the Revit file, every tile has an ID, and a summary that either says this one is a standard tile, nothing special, or this one is cut. Everything came basically prefabricated.

RS: So from the manufacturer, they're crating them up in order?

GM: Yeah.

The apparently random "wild bond" pattern of over 40,000 stone tiles was made possible by the parametric tools of MVRDV NEXT. Image © Ossip van Duivenbode

RS: So that was the role of parametric design in the tiled façade, but there was also a parametric approach to the shape, right?

GM: The story there is, on a basic level, we won the competition with this crazy shape that we were drawing as we liked it. Then the client said “ok, but how do I know that this is the right shape?” Well, good question.

From there, we decided to go with a more parametric approach, to make it measurable. So we started to script on sunlight, on overheating, on privacy, on terraces, those kinds of things, and then you end up with like this whole catalogue of endless possibilities. Some were better than others, and at a certain point we had a live script so that we could see, if we pull this part here, it was red but then it turns yellow. In the end, the result was very, very close to the competition design. That was very intriguing.

Then we made what was called the “angle snapper”. Until that point everything was drawn by eye, so it was, whatever, 42.793 degrees. We were a bit scared to make that more repetitive. We did tests on the west tower, and first we tried rounding every angle to the nearest five degrees. I didn't see anything move, so that was fine. Then we tried ten degrees. Well, I saw it move a little, but it’s still okay. Then 20 degrees… woah, way too much. So now, an angle is 70 degrees, 80 degrees, and so on, and that allows for more standardising of different types of connections.

RS: How many different angles are in that facade? What's the maximum obtuse angle you have?

GM: I think 40 degrees is really the sharpest, also because of production reasons for the natural stone. At the other end, I think we have like 160.

The structure of the towers is based on a "hash tag"-shaped layout of supporting walls 

RS: What were the greatest challenges from a structural engineering and façade detailing perspective?

GM: The structure is interesting: even though it looks like it is a very complex building, from a structural point of view it is not that complex. It's very weird to say, but it really isn’t, and that’s one of the things that made it possible to build. The basic idea is that you have the core, an eight-by-eight metre square, and it has structural walls coming out from there. So if you look on the floor plan, you see something kind of like a hashtag. With that, you can continue the wall, make it a bit longer or a bit shorter, and it acts like a beam. Once you have that, the only practical issue is that the floor shape has this jagged edge.

RS: So all of the towers are small enough that this hashtag structure is enough to support everything?

GM: In some places there is an additional structural wall, which also then continues up through each level. Then there’s also the specials, and there was some negotiation with the client over how many specials we could make.

RS: The specials, these are extra steel structures that are bolted onto the concrete to make some of the cantilevers.

GM: Exactly. Some are about eight by five metres, which is quite a space. But they give this feeling that you think everything is super crazy. They push that perception over the edge, so you think that it's next to impossible to make this. From a structural point of view, they are amazing. They are bolted into the concrete wall behind, and these bolts are almost too heavy to lift.

RS: So how many of them are there?

GM: There are eleven. We were allowed to make twelve but during the process, the structural engineers realised that one of them was possible with the normal structure. I thought, damn! I wish I knew that, because we would have made one more!

The structure features eleven "specials" that help to give an extreme impression of the overall structure. Image © Ossip van Duivenbode

RS: You’ve talked a lot about the structure of the towers, but then if you look inside the grotto, there’s also a kind of internal cantilever there. And then there’s the glass water pools. Was that also a challenge? 

GM: Yeah, the glass pool was a challenge. There's no Valley without a nice piece of water, right? So our valley has some water. Then we needed daylight in the grotto. We thought, let's combine them, make it from glass and put water on it. We also wanted glass beams, because you know MVRDV: if it’s glass, then it’s glass.

In the end though, it's fairly simple in a sense. There are these big U-shaped “shoes” inside of the structure, and you simply put the glass beam in them. Then on top of that is a smaller profile that holds the glass for the roof – triple glazing, double secured, and everything. Then some silicone in between.

But to get all of that organised… yeah, there were endless meetings about it. That was quite a struggle. To have an idea is one thing, to make a detail is two, but to keep the detail, that’s another.

The skylights in the Grotto double as water pools for the valley level above. Image © Ossip van Duivenbode

RS: That’s maybe the thing that I find most interesting about Valley – elements like the glass pools are audacious. And I know it can be done, but I also know the reason it’s usually not done is because it’s expensive, right? How do you convince everyone to keep that? Why wouldn’t that just be a glass skylight, without water for example?

GM: Because it was so interwoven into the building concept that… well, there are certain things that you simply cannot take out. You couldn’t just make it a regular roof light. That’s also partly because it was a competition, and it was already so widely published that the public had expectations already. That was an advantage for us, which allowed us to keep all of these challenging elements.

Still, it takes a lot of time and effort to get it built. You get the subcontractor who tries to simplify things, and says “yeah, we’ll just do it like that”. You have to say, no you won’t. Then you need to get a different supplier to give you the information you need to take back to the original supplier and convince them to do it properly. Of course, the contract has been signed, so that second supplier will not really make it, but you just use that information to influence the first. You need a lot of close relations that you can call to give you the information you need.

RS: That’s an interesting tactic! Are you then paying that second sub-contractor just to give you the information? Or is it a friendly agreement?

GM: That’s just a friendly approach. But obviously, the thinking is that maybe the next project we will do with them, of course.

Anyway, in the end I think for three years, I was on the construction site for the whole of Wednesday every single week, always overseeing the work. That is an effort that I think not many people make. We also didn't get paid to do all of it. But I had to endlessly keep pushing to make it really happen, because the contractor will take a shortcut the second that he sees that he can.

RS: So is this only a combative relationship with the contractor? Or was it a case where you can go there and see that they did something well say "well done, great job"? 

GM: It is a bit of a competition. The only way to combat the contractor is to go full push. I always went in with rolled-up sleeves and I would be as hard as I could. There was really a lot of tension. Then at a certain point, the construction starts and you see that they're doing a good job, but still you have like 29 issues that you need to solve. In order to keep the hierarchy in order, you need to be careful not to be too kind. That is a very shi**y thing to say, but if you are too kind, then they roll over you, and then it's all over.

This kind of hate-love relationship is needed to push it to the next level. Only at the delivery of the building, the handover – I know the guy is a big football fan, so I made this huge football-style trophy plate, I engraved Valley into it. At that moment I could say that he was the hero of Valley and without him, we could have never made it. Which was actually true, but I was never in a position to say that until the very end. So there's a lot of respect. He was really, really amazing and he had the process under control, it was fantastic.

Image © Ossip van Duivenbode

Find out more about the design of Valley here.