Cross-laminated timber is a fantastic construction material and it offers great flexibility. But it comes with a problem: glue.
Glue is used to keep the wooden layers together... and glue is a chemical compound you might not want in your walls.

What if there was an alternative to CLT that is made 100% of natural wood?

It turns out there is... 

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Mr. Erwin Thoma (on the right) with his son Florian and daughter Elisabeth Photo © Thoma Holz GmbH.

There is a company in Austria that is building massive timber elements without using any glue.
They use a system of pegs to keep the layers of wood together.
The name of this company is Thoma.

We interviewed Florian Thoma (engineer), son of Erwin Thoma who started the Thoma company.
The story of Thoma is a perfect example of how starting out with a simple concept, high standards, drive, and dedication can result in an inspirational legacy.

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Thoma was founded in 1990 because Erwin Thoma wanted to build the healthiest house for his children.
The company invented DLT, Dowel Laminated Timber, and established Holz100 (or Wood100) trademark method of construction.

Today the company has received several awards as an environmentally friendly industrial company.

Like many successful companies, Thoma began its operations on a very small scale.
They simply wanted to solve a problem that existed for one man & his young family.

Florian explains “back in the 90s there were a lot of heavy formaldehyde problems, a lot of building materials were contaminated with chemicals and when I was a kid we moved to a new house. When we arrived at a new house, we became sick, we think mainly from the contaminated materials present in the house. And so, my father started to pull out these materials & replace them with healthier things, such as wood floors & very good furniture, instead of cheap stuff made from chipboard.

Erwin, Florian’s father, changed the environment his family lived in and soon they became healthy again.

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He realized his idea worked in his home and it would work for others as well.
A new philosophy for construction was born.

Today, Thoma still operates on the same principles: to keep people healthy by avoiding chemicals in the building materials they use to build homes.

Now, nearly 30 years later, and with Florian leading the company, the principle is backed up with years of research, experience, and respect throughout the industry.

From that time this is still what we do today. There are many building materials you can use to build without chemicals, but our chosen building material is wood. Every piece of wood we use today is chemical-free. We don’t treat wood with chemicals and we don’t use glue at all.

This determination to keep their building materials chemical-free led Thoma to make its most important invention.
Thoma, with its anti-chemical ethos, found an alternative method of creating multi-layered timber elements.

Today, the cross-laminated timber (CLT) technology still predominantly today relies on creating elements by gluing thin layers together (although some are using nails, like in MHM).

Florian explains: “the big industry solved the layering with glue because this is the typical industrial thinking they have. This was not an option for my father and, in the late nineties, he came up with the solution to connect the layers mechanically, with a wooden dowel (a wooden peg).
For the last 20 years, we have been developing the DLT (Dowel-laminated timber). We started in the nineties and today there are more companies that also have this idea and we are happy that we are not alone in the market. However, where they might use aluminum or nails to join the wood together, ours is 100% wooden construction, which has lots of advantages.

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Thoma has, what Florian calls ‘a great interest in working with the wood to ensure very good quality.

In 2000 the company built their very first factory in Austria, with the aim to focus on the quality of their materials.
At their sawmill, also in Austria, they are able to have complete control of the quality of the wood from beginning to end.

Here the company can control how & when the wood is harvested, as well as ensuring storage conditions are in-line with their own, very stringent specifications.
The firm focus on how their wood is grown, cut, and stored has led to enormous improvements in the quality of the wood they use, which in turn has helped the development of new products and techniques for the company.

Now, through their own technology & diligence, Thoma offers what they’ve named ‘Wood100’, meaning a complete house can be constructed only using all-natural, expertly crafted wooden components. No mixed materials, no chemicals, and no limit on imaginative design.

Working in partnership with a network of architects, planners, builders, carpenters, and logistics teams, Thoma can work on any design to create the components needed for a complete house that promotes health & vitality for its inhabitants, using only ‘the pure magic of trees.

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While the effects of living in a house made of chemically treated materials remain to be thoroughly researched, Florian is keen to use scientific thinking to prove the benefits of avoiding chemicals altogether.

The theory is that stress leads to a lot of diseases we have in our civilization today. How many materials do we face today when we build houses out of tens of thousands of different materials? We developed these materials in the last 60 years, they are not developing in line with our evolution. So, when we enter the modern-built house, we are interacting with thousands of unknown materials and we feel that this is not safe, we feel stress and constant alertness. 100, 200, 500 years ago we built houses from maybe 10-15 different materials and they all came from local sources. We know these materials, they do not stress us. This is the reason why, when you enter an old wooden building you automatically feel at home. You cannot say that when you enter a new office building – you wait to leave the building before feeling healthy again.

To support this thinking Florian describes a study carried out by an Austrian physiologist who measured subjects’ physical responses to spending time in different environments, like the type described above.

The findings suggest that spending time in wooden, chemical-free environments can noticeably reduce heart-rate, a strong indicator of how stressed or relaxed we feel.

When you sleep in a massive wooden room, without chemicals your heart-rate slows by something like 3,600 beats per night (that's about 7.5 bets per minute less than the usual). With school children in this type of room, their heart-rates dropped by over 8,000 beats over the day! They were more relaxed, not tired. They were better focused on their lessons, recovered better and faster from stressful situations. So, the thing is when we’re in contact with natural materials our body feels safer, less stressed.

On top of their homes being healthy for people living inside them, Thoma places a strong emphasis on environmental factors, such as self-sufficiency & waste-free homes.
These should be a priority.

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Taking into account the geographical features around the house (i.e. whether the surrounding land is forest, high altitude, etc... ) & carefully calculating the building materials and design features, the Thoma is experimenting with buildings that require no heating systems but also no insulation either.

It’s an impressive goal which so far, is yielding impressive results.

Florian tells us about a 4-story house built in Switzerland with this very design: no insulation, no heating system, just a wooden building with windows and a clay floor which absorbs the heat from the sun to keep the building warm for up to 4 days.

Within 4 hours this floor stores enough energy to keep the house warm for four days without sunshine. It’s cold there, but there’s never more than 4 days without sunshine. It’s a prototype that only works because there is a massive wood around the house, so there are no peaks of heating & cooling. It is experimental and it wouldn’t work everywhere but it shows what is possible; the potential of what we can do. The owner has lived in this house for five years, and not spent a single Euro for heating... there’s not even a pipe, solar panel, or anything to spend money on!

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Thoma Holz100 house in the Simmental (Switzerland). This house is built without a heating system and has dark color grey floors in order to collect the heat - Photo © Thoma Holz GmbH.

Florian acknowledges there are still some barriers to overcome before this type of construction becomes more mainstream.
However, he believes that building constructed using Wood100 principles will undoubtedly play a bigger role in future construction.

It’s difficult to convince the ‘traditional’ construction industry as the total building costs are around 10-20% higher... but when you don’t pay running costs or heating costs when you see the holistic picture, it’s the cheapest way of building. With proper investments in manufacturing, we could reduce the costings by up to 30%. In the end, when you think you’re not going to get poisoned by your own home, there is really no other alternative. We cannot afford to build in the old way anymore. But we will need to develop intelligent systems and certain economics to face this problem and make this type of building the obvious solution.

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Zinipi accommodation units - Photos of Zin© Klaus Schicker.