Can a house realized in prefabricated wooden construction stand in the center of a city? Such a house-prototype in Krakow was built by Bartosz Dendura's studio Studio4Space, proving that it's high time to dispel the myths about wooden architecture!
We talk to Bartosz Dendura about the advantages and challenges of this type of construction, why clients don't want to opt for prefabricated wooden buildings, what are the differences in the price of a traditional and wooden house, and finally, who would want to live in a black building
Ola Kloc: Th house is made in prefabricated wooden construction, what influenced such a choice?
Bartosz Dendura: Basically, from the beginning, our assumption was to make the building as ecological as possible, we selected all installations and technologies in such a way as to make it fit into the idea of sustainable architecture as much as possible. Hence the decision for a wooden structure. It was so much easier because we ourselves (together with my wife, an architect) were the investors, so we didn't have to ask anything.
In Poland it is still not a popular technology, it is badly associated. By the way, we are now doing surveys of Poles' behavior and perception of the ecological movement. Ecology in Poland is all the time understood as something inferior, something of lower quality. So we tried through this project to prove that this is not quite the case. We are not forerunners of this solution in the world, after all, it is used successfully in many European countries. In Sweden, Switzerland, Germany they are used on a daily basis, somehow in our country they still can't break through, especially for investments a little better than standard. When we talk to customers and offer them wood technologies, they never want to accept them.
Ola: What is the reason for this?
Bartosz: We have a very strongly ingrained image of a Brda-type wooden summer house, which smells, crackles, is damp, absolutely unfriendly to live in. And these are complete different buildings — you can't compare them. When we sold the house on Olsza, practically only young families came to the meetings. They were accompanied by their parents, who were often the main sponsors of this project, and advised them against this solution, saying "buy a normal house, a brick one, and not some wooden experiments, because, after all, you are supposed to live in it for years". Maybe the younger generation would be ready for it — by the way, the fact that it was young people who bought the house proves it — but anyone who still remembers the period of communism and poor construction, including that of the early 1990s, has not the best associations with wooden construction. So we wanted to show that it's possible to make a contemporary building based on this technology, and that it could be a building that would fit into the city center.
bird's eye view
photo: Bartosz Ciotek, INPHOTO
Ola: You didn't stop at the structure itself, but also introduced passive solutions. Do you need to convince investors about them too?
Bartosz: No, I think we are slowly being convinced of this in Poland. Of course, many factors have influenced the fact that we are investing more and more willingly in pumps and photovoltaics. Rising prices of other energy sources are pushing people towards these solutions, so I'm not convinced whether this is due to a sense of environmental responsibility or whether economic issues are more appealing. On the other hand, the very fact that this is happening is probably a plus.
In this project, even though we had MPEC on the plot, we found that since our premise was to be green from start to finish, we had to do a pump. Due to the fact that the plot is very small, a ground pump was out of the question, and due to the presence of water reservoirs, it couldn't be a submersible pump either, so the only option was to use an air pump. Combined with the roof, which is entirely covered with photovoltaic panels, this solution balances out to some extent. For this, we used mechanical ventilation with recuperation — it is solved in such a way that the air intake is located in a protected space, so that the air that enters the building in the summer is cooler and in the winter warmer than that outside. This results in less energy consumption to cool or heat the blown air. The construction itself also contributes to the effect — there are 30 centimeters of mineral wool in the walls, so they are very well insulated.
Ola: So the goal was not only investment issues, but also a certain mission, to prove that such architecture can also create a city. How do you assess this mission in retrospect? What were the challenges during this first implementation, and what are your further plans?
Bartosz: Despite numerous attempts to convince clients, this was the first realization where we actually had the opportunity to participate in every stage of construction, and it was up to us to make all the decisions. This is not always the case, and this is the only way to take care of even the smallest detail in a building.
photo: Bartosz Ciotek, INPHOTO
Ola: You didn't manage to convince anyone of these solutions before?
Bartosz: Always customers choose brick buildings, traditional construction. Anyway, still non-traditional construction is marginal in Poland. According to data from the Central Statistical Office for last year, an average of 250,000 apartments were completed in Poland — both in blocks of apartments and in single-family houses — and only 1.4% of them were built with non-traditional technology; this includes prefabricated, concrete, steel and wooden structures, so we're talking about the absolute margin of construction in Poland. Everyone builds with bricks, using wet-poured ceilings — this is the standard to which we are probably accustomed.
Since this building was built, we haven't had the opportunity to start another development of our own. This is not any big development just a private operation, I treat this building as a showcase, I invite clients to it to show them what it looks like. That going inside, they will not realize that they are in a wooden building. Myths are still being propagated that a wooden building crackles when it blows. I even witnessed a conversation among neighbors who wondered if this building would collapse onto their lot in a bigger wind. Prefabricated systems, yes, have a wooden structure inside, but it is filled with mineral wool, and the walls are additionally reinforced with fiber-cement boards on two sides, which give them statics and strength. Also, this building is as rigid as a brick building. There is no chance of anything happening there at all. The base is concrete, so it stands solidly on a foundation slab, and the top is prefabricated, which was installed in two weeks. Then there was a whole period of installation, finishing, etc. To sum up, construction took exactly one year from the time the building log was pulled to the notification, but the period of erecting the structure itself was very short.
The material on the facade is Siberian larch
Photo: Bartosz Ciotek, INPHOTO
Ola: So let's move on to the challenges.
Bartosz: Challenges definitely, and ones I didn't anticipate beforehand, were logistics — a large transport had to go into the narrow streets. The crane that was feeding the elements had to stand down for two weeks, so the traffic organization had to be changed, blocking off part of the housing development for two weeks. Delivery — I didn't take into account that the low-hanging cables would be a problem, and some temporary supports had to be erected for the cables so that a truck could pass under them. Other challenges were related to various design decisions and a lack of advice from renovation and construction companies. One example was something that at first glance seemed like a brilliant solution — blowing wool on the ceiling. The densely spaced trusses add rigidity to the building, and it seemed to me that if I made the wool blow between them, it would reach every nook and cranny. Well. It turned out that this was the worst thing I could have done! Due to the fact that the truss is dense, the wool could not reach those farthest parts of the ceiling. When we reviewed the entire building with a thermal imaging camera in winter, you could see large patches in places where the wool couldn't reach. Consequently, the whole job had to be redone from scratch, otherwise the idea of a building that is airtight and doesn't require much energy for either heating or cooling would completely lie in ruins. So there were a few design decisions where support was lacking, and I had to convince myself that something should have been designed differently. As a result of being both an architect and an investor, this was probably easier for me to swallow.
White frames highlight the window openings
Photo: Bartosz Ciotek, INPHOTO
Ola: Having already had this experience of building a building of this type from scratch, did you gain new arguments that could convince potential investors in the future?
Bartosz: Apart from time, apart from the awareness that we are moving in the spirit of sustainable development, apart from all the research that proves that the climate that prevails in wooden buildings is simply better than in masonry buildings, because they breathe, give off moisture and the prevailing aura is more favorable, I don't know what else I could encourage. Being inside, we are not aware that we are in a wooden building, and someone who is afraid that he will smell the wood too much then, if he doesn't want to, he doesn't have to see it at all.
For the purpose of a lecture, I made a summary showing why green, wooden, prefabricated construction is not being adopted too much in Poland. I took the liberty of dividing investors into three main groups. One is those investors who have a very limited budget and for them the essence itself is to put up a building into which they can move from some small apartment, and for them the ecological aspect necessarily recedes into the background, because the most important thing is to have a house. They also mostly do not use the services of architects, but buy ready-made designs, that is, they have a very limited opportunity to seek advice or seek information, they get information full of myths from the Internet. These investors mostly do not opt for wooden structures. The second group are investors who have more financial slack and can afford something more expensive, but have the conviction that since they are building a house for years, investing often several million in it, why should it be made in a wooden structure, which they believe is not permanent, is something inferior. The last group, somewhere in the middle, is a very narrow group of people who, on the one hand, have this environmental consciousness and, on the other hand, financial capacity, because, let's not kid ourselves, prefabricated wooden construction is more expensive than traditional construction. It may not be drastically higher costs — I estimate that I paid about 15-20% more for this house than if I had realized it in traditional construction. In the case of wooden construction, there is one disadvantage — you pay in two weeks the entire amount. Why is the average construction time for a single-family house in Poland 54 months? In one year investors build the foundation, in another they put up the walls, then make the trusses, building in such stages as the money flows to them. A prefabricated wooden structure is ready in two weeks and after two weeks the investor gets the invoice. This is a factor that causes not everyone to be able to afford it, and those customers who can afford big, expensive solutions treat it as something inferior, they think the house must be concrete, solid, preferably like a bunker — then they are happy.
In conclusion, the pluses include the speed of construction, the climate in the building and the fact that we are putting up a building in the idea of sustainable architecture.
front elevation and cross-section
Ola: The building is far from the stereotypical visions of wooden or prefabricated houses. Why such solutions — flat roof, offsets in the massing?
Bartosz: These are strictly design assumptions. This is a semi-detached building. However, we wanted to make sure that when looking at it from the street, it didn't feel like a composition in its entirety. Hence the differences in height, glazing, one enters the building from different sides. Similarly, with the flat roof — it seemed to me that such a roof would play better in the contemporary body of the building located in the city center. All these assumptions proved to be a challenge for prefabrication companies. We wanted all corners to be glazed. Most conversations with manufacturers' representatives began with suggestions for changes in the design — they drew us mullions at each corner, which for us spoiled the form and took away its lightness. We designed ribbon windows going up to the roof, so the cornice beam had to be moved inward, again a design non-obviousness. Many of the companies we talked to, even the leading ones, were not interested in taking on the project, because it required a little more commitment, we had to think outside the box, recalculate the structure from the beginning. Only when we managed to communicate with this particular company did it take off. But this is some architect's vision.
ribbon windows going to the roof
Photo: Bartosz Ciotek, INPHOTO
Ola: Please tell us about this vision of yours!
Bartosz: We knew from the beginning that it would be a semi-detached development, it was prompted by the economic calculus, it was the most cost-effective option. Subsequent decisions were set in terms of the ecological aspect, including the choice of material for the facade, it is Siberian larch, which is characterized by the fact that it is a dense tree, it does not work so with temperature changes. We opted for burnt wood, which does not require chemicals, because this millimeter layer of burnt wood makes the material resistant to moisture, to fungi, a plus is the black color, which as architects we like. Although I have already heard opinions that this is the ugliest building to be found in Olsza, well, because who would want to live in a black house! The white frames are supposed to accentuate the window openings, and at the same time, the white treatment inside brings more light inside. Maybe from the front or street side you can't see it, because there isn't much glazing, but the garden part is very glazed. There is a large glazing passing on the principle of stepping stones, that is, without a pillar, without a support in the corner, from the living room we have a view of the entire — not big, because not big, but nevertheless — garden. The bushy plots of the neighbors mean that from the windows you can see the greenery itself. The effect is surprising, especially if we're talking about a plot located 3 km from the market. It came out a bit by accident, but it worked out very well.
Photo: Bartosz Ciotek, INPHOTO
Ola: Do you already have the first feedback from residents?
Bartosz: I don't yet have information on what the impressions are after the first year of living here, while I have a preview of how much energy this building uses and how it balances out. To assess this, I'm waiting until October, when it will actually be a year since the building has been alive, but so far it's clear that the effects are quite good. The energy consumption is relatively small for the fact that everything in the building is on electricity. Despite the pump's high consumption in winter, it doesn't approach the limit of 10,000 kWh, a level that is quoted as the average electricity consumption for a pump building of about 150 sq. m. For now, estimates are that the entire consumption should be between 5-6,000 kWh, which means that in combination with photovoltaics, both the issue of building use and the demand for utility electricity will balance out. Also, it looks pretty good.
Ola: Thank you for the interview.