Boom of wooden buildings in Sweden started by change in legislation

Yes. At the same time, it is important to remember that Sweden has a huge amount of forests, and wooden buildings in general have a very long tradition here. But I remember when I joined White Arkitekter, there was a lot of discussion about how to convince clients to choose a timber structural system. It took a long time for clients to get used to it and go for it, because they didn’t know how such buildings would behave. It is logical, however, as large buildings have always been built here with different materials and can therefore be easily priced. That’s why concrete and steel led for a long time. But then the first big wooden building was built and everyone came to see it, they were interested in the construction, construction technology and details, so it slowly took off.

Even in the context of competitions, we first proposed two design variants so that the client could choose. Mainly so we don’t scare them off with the wooden structure.

Yes, that’s how it started in Sweden. The legislation did change, but it took a long time for the market to get used to it. It makes a difference whether a two-storey nursery or thirty thousand square metres of offices are built out of wood. This simply carries with it various risks and if someone decides to go down the new path of wooden buildings, they must be sure that there will be no problems.

And the other big thing was the price. Large wooden buildings were initially more expensive. We had to demonstrate to our clients the ecological footprint, the speed of construction and look for different arguments to make wood construction profitable for them.

In the office, we have sustainability as our core mantra. We set plans for three years and a decade, and we have committed to making all our buildings carbon neutral by 2030. And we can only do that by using more wood and less concrete and steel. So to achieve that goal, we have to build with wood, because wood is the most sustainable building material we have at the moment. The second thing is the operation of the building so that it is as environmentally friendly as possible.

No, it depends on what the structure can do and whether it is fire compliant.

They don’t succumb, there’s no stigma attached to wood here anymore. Today, it is more like concrete and steel. It seems to me that everybody’s sick of them. We’re working on a competition right now and instead of using steel columns for the as-built part of the building, we’re figuring out how to replace it with wood.

It is purely about the carbon footprint. As I said before, every new building in Sweden has a certain so-called. carbon budget, and if we were working with a steel structure, we simply wouldn’t meet those requirements. And because sustainability is essential to us, we try to design the most sustainable buildings possible, whether anyone wants us to or not.

Everything can be replaced with wood, even the elevator shafts as stiffening elements. Wooden cores are easier to handle. However, we sometimes pour the ceilings with concrete for acoustics or for the load of the building.

It’s not quite that simple a comparison, there is no general pattern for all buildings. A lot also depends on how timber prices move on the markets. This has a big impact on the final price. For example, for wooden buildings, the construction time is much shorter, or the transport of structural elements to the site in terms of their weight, etc. I was looking at one project where we did this comparison, it’s a high school from 2021 and 2022. The study showed that the wooden construction was about 10% cheaper, but the so called. weather protection during construction drove up prices, and ultimately drove up costs, so the building cost about 5% more than the runway.

This comparison becomes more interesting when we start working with carbon offset or carbon tax in the construction cost. In Sweden, the carbon footprint will have to be declared to obtain a building permit and the next step will be to introduce limits. In France, for example, this has been in place for some time and Paris has gone through several tightening of these limits for obtaining building permits. On the last project I worked on, the preference for timber construction rather than concrete or steel reduced the carbon footprint by 75%.

Five years ago, we were still dealing with the issue of price, but today we are practically not dealing with it at all.

I don’t know of any concerns, but maybe it is also due to the fact that wooden houses are traditionally built here.

We have to deal a lot with acoustics. Wood is a lightweight material and therefore sound travels much more easily in it than in brick, for example.

Another big problem is humidity. Maybe that’s problem number one. There is a need to ensure that construction takes place in as dry a climate as possible. It is often discussed with the client whether to build under a tent or not, as this is a factor that significantly affects the overall price. And when it comes to high-rise buildings, covering can be quite a problem. What is, for example. The SARA Kulturhus project, construction under cover was abandoned and the winter months were chosen for as much of the construction as possible. In winter, the air is not as humid and the snow is much, shall we say, drier than rain and can be swept away. With the house being so far north, winter conditions were not such a problem. This is also related to the fact that when fireproofing is applied, the wood must be ultra-dry.

As far as the supporting structure is concerned, we work exclusively with wood. We do a lot of projects in the studio, but at the moment I can only think of one concrete building in Kenya, which we started in 2016, and because they don’t build with wood at all, we chose concrete. We even thought about sending timber by boat, but it didn’t make sense.

In addition to wood, we also try to work a lot with recycled materials, especially in the case of demolition of existing buildings. How to reuse the materials is a big question for us now. We use recapture software, which scans the whole house, labels all the elements in it, and then the software breaks it down into individual elements, from which we choose which ones we could use. We have a whole department in the studio that deals with this.

No, there isn’t … there are different kinds of certification (like Miljobyggnad), for example, according to carbon footprint, which gives the building a certain status and makes it more interesting for potential tenants. This makes it easier to rent it out even at a higher price.