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Clay builder with sustainable ambitions

Snickers Workwear - Global

As a recently graduated architect, Hanna Nilsson dreamed of helping the construction sector to be more sustainable. And that’s exactly what happened. But not in the way she imagined.

We’re in an old limestone house in the village of Kastlösa on the island of Öland, the second largest Swedish island, which is located in the Baltic Sea, just off the coast of Småland. In the attic, Hanna Nilsson is smacking clay onto a brick. This is going to be incorporated into a type of fireplace invented more than 30 years ago, but that never really took off.

Hanna, what’s the deal with this oven you’re building?

This is a type of oven that was invented in Finland in the 1990s. It’s made exclusively from natural materials – clay, brick and a little mineral wool. There’s probably no other fireplace that utilises the energy in the wood so efficiently. If it’s designed properly, it only needs wood to be added once or twice a day. The energy released during combustion is stored in the mass of the oven and chimney and is emitted over 24 hours in the form of radiant heat.

It does sound a bit odd for a recently graduated architect to change career so drastically. What happened?

I’ve always dreamt of being able to do my bit for a more sustainable construction sector, ideally in a profession somewhere on the boundary between art and construction. And building something beautiful and functional involves just as much manual labour as drawing and designing. But I would never have become a mason if it weren’t for Johannes Riesterer.

“I discovered clay, the ultimate construction material. It’s moistureregulating and organic, and it’s a more or less unlimited natural resource. I couldn’t imagine doing anything other than clay building nowadays.”

Who’s that? And how did you meet?

In my view, Johannes is Sweden’s top clay builder. I ended up attending one of his lectures quite by chance, and I simply felt I had to work for him. His view of artistic crafts and ecological approaches throughout the construction process really struck a chord with me. I nagged until I was given a work placement, but I really didn’t believe I’d still be there four years later!

Was it at this time that you seriously started thinking about what sustainability involves?

No, I started thinking about smart resource utilisation, organic materials and the natural ecocycle at an early stage. I spent a year travelling around Europe before I became an architect. I visited organic farms and met some like-minded individuals who were also looking for a sensible way to live.

How sensible is clay as a construction material?

Clay is fantastic in all regards. It’s cheap, it’s easy to combine with organic material, and it’s not corrosive or allergenic. It’s almost always available nearby, too, which means short transport distances. Practically every village here on Öland has its own clay quarry. I recently restored a staircase in my own
home village of Gärdslösa. Quite simply, I was able to get hold of the same clay that was used to create the staircase 150 years ago. That tells you something about the sustainability and availability of the material.


Clay is one of the oldest construction materials in the world. It’s been used throughout the ages, at the four corners of the globe, to build everything from cottages to castles and mansions. A significant proportion of the Earth’s population still lives in houses made from clay or soil in some way. Plastering walls with a claybased mortar to provide insulation against draughts has been traditional in the Nordic countries since the Viking age. The smooth clay surface provides a fine basis for distemper and a smooth surface for wallpapers. Clay mortar differs from other mortars such as lime or cement mortars in that it does not burn. So in other words, there are no chemical reactions during the drying time. This makes the clay water-soluble, but also very elastic. This makes it easy for it to follow movements that can occur at high temperatures in an oven. Clay can be mixed in advance and stored over a long period.

I see you’re using clay on the walls as well?

I’m sealing against draughts using a clay-based mortar. This provides a healthy indoor environment. The clay plaster stabilises ambient humidity while also absorbing dust particles.

What’s the clay mixture made of?

Various products taken directly from nature: Clay, sand, straw, water and manure from cows or horses. It’s beautiful to think that a clay house that’s left to decay will completely return to nature over time. With no negative impact on the environment. This reinvented restoration method is very interesting in the current hunt for energy and search for cheap and wholesome construction materials.

“Creating the perfect clay is a complex task. The colour and consistency are governed by the climate and clay type in the area. Clay can be anything from white and yellow to red, blue, grey, brown and black. It’s more or less plastic and more or less water-absorbent, and its fire resistance varies. This turns every new project into a challenge.”

What are your thoughts on workwear?

I want to be able to look forward to a long career as a clay builder. It’s hard work. Your clothes have to work with you. So if your kneepads don’t stay in place, that’s just not good enough. Or if your jacket doesn’t fit properly because it’s actually a men’s jacket in a small size. And of course, quality is every bit as important. Today’s throwaway attitude towards clothing isn’t sustainable for the environment. Quality garments designed to last a long time – that’s what I call sustainable workwear.

You helped to develop Snickers Workwear’s new work trousers 6701 and the jackets 1107, 1207 and 1367 for women. Did they listen to what you wanted?

Definitely. It was clear that the product developers at Snickers had a genuine understanding of the challenges I face every day at work as a female tradesperson. It’s about time someone focused on workwear designed specifically for women. And when we tradespeople have the opportunity to try things as they’re developed, the designers get it right first time.

Profile Hanna Nilsson

Hanna Nilsson started her career as an oven constructor with Johannes Riesterer, a man deemed to be one of Sweden’s top clay builders. After four years as an apprentice, she started her own company, HannaMurare, with the aim of focusing on sustainable production.

Age: 33.
Family: Fiancée.
Where I live: Gärdslösa, Öland.
Profession: Clay builder, oven constructor, architect, artist.
Place of work: Runs the company HannaMurare, holds courses on clay building and oven construction.

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