Pièce de Résistance

Interview with Alexander Brenner and Elias Baumgarten

Alexander Brenner talked to Elias Baumgarten about the Parler Research House PR39, in which Brenner himself lives.

Alexander Brenner is very critical of building products. He is concerned about much that is happening today as part of the industrialization of building. He fears a further loss of quality, durability and sustainability. Yet just complaining about this is not his style. Instead, together with building firms and clients who share his passion for quality in architecture, he is going his own way. In this interview he sets out his position. We talked to him in Stuttgart about the Parler Research House PR39 and learned about the particular challenges and characteristics of this project, one into which he has concentrated more than two decades worth of experience designing and building over individual 40 houses.

© Zooey Braun

The interview

Baumgarten: Some people refer to you as a “villa architect”. Someone who fulfills the wishes of highly privileged clients with very deep pockets, they say. This sounds disrespectful, but it probably also reflects envy. What´s certain is that this does not do justice to your architecture. You are an independent critical thinker and not in agreement with much that is happening in the building industry today; standard solutions are not your thing. So, let´s talk about your general approach first before we turn to this specific project, the Parler Research House PR39. What is it that bothers you so much, what exactly do you take issue with?

Brenner: Today, unfortunately, large quantities of dubious chemicals are used in building, and, to save time and money, the actual building is done hastily and by people who do not have a thorough understanding of the work. Often interior fit-out takes place before the building has dried out and future problems are covered up by the extensive use of synthetic materials. The market is overwhelmed by a flood of unnecessary building products, some of them just plain bad. Raw materials and supplies are brought from far away, rather than sourced locally. For example, if you ship stone to Stuttgart from China, it´s cheaper than buying it from the local region. The same applies to skilled tradespeople: it´s cheaper to find and hire people from Eastern Europe than to employ locals. Few seem really interested in keeping value chains short and helping to strengthen the regional building firms and tradespeople.

Houses are often built from the outset for a lifetime of just 25 years, and you can assume that after that time they are only fit for demolition – houses are seen merely as commodities. All that seems to matter is the square-meter price. In Germany, society seems little interested in good and sustainable buildings. Also a whole host of standards and regulations is holding back innovation here, or preventing simpler, better and also traditional, tried-and-trusted solutions. We are standing up to this and pursuing our own way. What´s important to us is a meticulousness, sustainability and durability. The way we work is holistic, we aim to produce a “Gesamtkunstwerk”, to use the language of architectural history. All our buildings are designed through to the last detail, we always also design the interiors – everything from furniture to lighting, and the gardens. In doing this, we frequently find ourselves developing sophisticated customized solutions, some of which can be very far removed from the current rules and conventions.


Baumgarten: Let´s explore that a little more: When it comes to the energy performance of a building, you are against the use of multi-layer thermal insulation systems. Only one of your projects has this – and that had a structural reason.

Brenner: Just consider for a moment what exactly a multi-layer thermal insulation system does from the point of view of chemistry and physics: render, which is actually more of a synthetic-based adhesive, is applied to soft insulation board. Because of the strong insulating effect the façade always stays cold and damp. In such an environment, all kinds of fungi and algae will grow, you can´t avoid it. So the “render” is treated with fungicides and pesticides. And to ensure these are effective, they need to be water-soluble. So the rain is constantly washing poisons down into the ground around the building. After five years you have to retreat the façade. How can anyone seriously want that, and then claim that it´s all sustainable and energy-efficient?

For our walls, we choose 50 cm or even 62.5 cm thick blocks of aerated concrete – that for me is one of the best building materials currently on the market. On the outside we use a mineral-based breathable thick plaster system from KEIM; inside we use a lime finish from the same company. In my opinion proven and traditional materials like these are paid far too little attention.

But we don´t want to just complain, instead we seek opportunities to develop new solutions, together with the manufacturers who share our way of thinking. These solutions don´t always have to be brand new, they can be adaptations or modifications of existing products.

Passion, dedication and persuasion

Baumgarten: You have already indicated that some of your developments, or detail solutions, run contrary to existing norms and regulations. Is that not a problem for the companies and tradesmen with whom you work? Because it is they who will be liable if there is a claim for damages.

Brenner: Firstly: We have never had any dispute or legal proceedings because of building defects. We work at lot with always the same firms, in some cases for decades. Our partners are passionate about what they do. They share our beliefs. Yes, when we take on building projects at places far away, in Germany or abroad, we look to supplement our team with local builders. Also, we don´t get involved in invitations to tender, instead we discuss the task and the challenges together, before any contract is signed. It´s very important to me to have a good and respectful relationship and a basis of trust with the tradespeople and the contractors. Our contractors also support each other, in a kind of modern version of the cathedral workshop of earlier times. In fact we have even designed the homes of many of our tradespeople.

Baumgarten: I assume your clients and your contractors are easier to convince of your philosophy, than associations that are fixated on time and returns?

Brenner: Our clients enable us to work in a way we think is right. I am now very careful in selecting for whom we build. I don´t want to design for people who don´t have the right attitude. For example, if someone is disrespectful to my team or the contractors, who do what is often a very dangerous job in all weathers, or if someone does not pay their invoices on time, then I have great difficulty seeing any kind of basis for cooperation.

Baumgarten: That sounds like luxury. What architect would not like to choose which commission they take on? But there is another side to this: You build mainly single-family houses. I know that sustainability and eco-friendly building are important to you. Does this not worry you a little?

Brenner:Yes, it is not ideal, I admit. But it is something we take on board. We would love in future to apply our concepts to larger residential buildings. And I´m pleased to say things do seem to be happening in this area now: Right next to PR39 we are building PR41, a residential building with three large loft apartments, each with 165 square meters of living space. That is a first step for us in the direction of higher-density housing and we are therefore talking to investors, developers and local authorities about it. Perhaps soon we´ll be building not just individual houses, but an ensemble…

Perfection in imperfection

Baumgarten: In the case of PR39 you were your own client. The house is right next to your studio. That must have been a great benefit…

Brenner: PR39 is an experiment. All of our projects have a certain experimental component, and that´s because we are always trying out new things. With this house we wanted to bring together the knowledge we have gained over a period of 25 years or more and to test out the limits of the possible. So this constellation was of course very practical.

Baumgarten: On the outside what you immediately notice is the bush-hammered concrete façade; you once said this was a “material of the future”. You have used this technique in a number of projects and you´ve developed it further, for example in the “Haus am Weinberg”.

Brenner: Years ago I watched a crusher tear up a concrete foundation that had been wrongly laid. It produced a wonderful texture, a bit like a coarse-grained sedimentary stone or conglomerate. With PR39 a stone mason from Bavaria worked the façade in the same way using a chisel. And so many people assume the house is built of natural stone. To enhance this hand-crafted look, we also did a boasted finish on the edges and corners. And it is the skill of the stonemasons at Miedl that we have to thank for the fact that this finish is straight, with no pieces broken off.

With our current projects we are using regional aggregates for the concrete. So these houses always have a reference to the local area and each of them is different. In the case of PR39 we used a light-colored limestone from the Swabian Jura. In Stuttgart we also add a dark shell limestone to the concrete. This was a challenge for the supplier, because he had to make sure each time that his concrete-mixing plant was carefully cleaned before adding the limestone. The supplier, Godel-Beton, took on this extra work with enthusiasm and dedication, and I am very grateful to them for that.

Baumgarten: There´s quite a contrast between this and the concrete chimney inside the house…

Brenner: That chimney was concreted in situ using a formwork system. 20 mm thick boards were used. And when you remove the boards, material inevitably protrudes through the joints – you can´t control that. So, while our plans are normally very precise, in this case we had little control over the result. We think it´s important to keep trying something new and do things we never dared to before, or which we were previously against.

I have learned – during my whole career and especially with PR39 – to not only accept irregularities and signs of the human hand at work, but to value it, because it would be a pity to make a house made by hand to end up looking like an industrially manufactured product.

Baumgarten: Is that the reason why the slightly angled parapet next to it was allowed to stay?

Brenner: One our long-term partners from the Karl Köhler shell construction firm – sadly he is now no longer with us – made a mistake in the calculations. So he was keen to take down the parapet and correct his error – out of professional pride and a striving for perfection. But I said no. At first he was very angry, before finally gritting his teeth and accepting it. He said it looked awful and it would cause me problems with the floors. But for me, things like that are a memory of the people involved. That has value. Getting rid of signs of human endeavor and leaving nothing to chance – I think that´s wrong. With this house you can see the joy that many people had in working on it. The stone mason, for example, spent eight weeks on the façade. He went to enormous trouble: for example, he even built special tools for working angled details on the balcony parapet; everything had to be finished to perfection. Today he is so proud that he refers to this house as “his house”.

Baumgarten: On the staircase leading up to the first floor, you can see screw holes. And you can still see the position of the spacers in the reinforcement.

Brenner: At one time that would have bothered me. I would have worked out a solution with the contractor in question that would have concealed these things or I would have avoided them from the start. The staircase was a complex construction, because of its ergonomic geometry: The lower part is in-situ concrete, the upper part is precast. The building process was complicated. The precast component had to hauled into position with a crane. And for that you need hooks. So, why cover up the screw holes? (Today) I see no reason to do so.

Testing the limits

Baumgarten: With PR39 you also tested the limits of the possible in terms of architectural and structural design. One thing that stands out is the delicate, boldly cantilevered canopy over the roof terrace, made of concrete, right at the top of the house. Looking at it you just wonder how on earth it can stay up.

Brenner: This “delicate” roof weighs a good 10 tons! Our structural engineer, Frank Zimmermann of Boll und Partner, originally suggested one 140 mm thick column. I wasn´t so happy with this idea and wanted a thinner one. Frank really knows his job and he is also a fan of our architecture. So, he sat down again with the figures and came up with another suggestion: 2 x 60 mm solid material, which take over 7 tons of the load from the roof.

Again I must emphasize just how much I respect the work of these tradespeople – just think how tricky it is to concrete this element in situ – and at that height! The concrete specialists at Karl Köhler used all of their expertise and experience on this project, although at first the idea of realizing this element in in-situ concrete seemed impossible. Recently a group of representatives from over 30 leading construction companies from all over Germany came to visit the house and look at all the concrete work – it was an excursion put on by their association. And they were all amazed at this roof bar.

Certainly with my house some things are really “on the limit”. For example, there are a few cracks caused by shrinkage - a normal client would certainly be concerned about those. But with our clients we always make sure they understand these issues. However, when you are building for yourself, you can go that bit further. And that is why the house is called a “Research House”, and I enjoy every day that I can live in it and continue the experiment.