Question 1

What is earth building?

Accepted Answer

Earth building is one of the oldest construction techniques in the world. It uses soil, sand, natural fibres like straw and other natural additives to create solid walls, floors and plasters – entirely without cement or synthetic materials. Clay naturally regulates humidity, stores heat and creates a healthy indoor climate. At Earth to Wall, we combine traditional building methods with modern techniques, working with cob, adobe, cordwood, rammed earth, wattle and daub, and straw-clay.

Question 2

Does clay dissolve in the rain?

Accepted Answer

Not with proper protection. Unprotected clay is water-sensitive, but a good roof overhang, a protective lime or clay render, and solid foundations keep earth walls safe from moisture. Earth buildings have stood for centuries around the world – in Morocco, Yemen, Peru, Germany (half-timbered houses with clay infill), England (cob houses in Devon, some over 500 years old) and France (rammed earth houses in the Rhône-Alpes region). It all comes down to good design and execution.

Question 3

Can I use clay in an existing home?

Accepted Answer

Absolutely – and that's actually one of the most common applications. Clay plaster can be applied to almost any standard surface: masonry, concrete, plasterboard, old render. Natural wall paints made from clay, lime or casein work on virtually any surface. Clay floors can also be installed in existing rooms. Beyond that, clay is excellent for thermal upgrades, partition walls using techniques like wattle and daub or straw-clay, and many other applications – from tadelakt in bathrooms to clay thermal mass walls.

Question 4

I'm a complete beginner – can I learn to build with clay?

Accepted Answer

Yes, absolutely! Especially when it comes to integrating clay into existing buildings, the barrier to entry is very low: applying plaster, mixing natural paints, pouring floors or working with tadelakt – all of this can be learned step by step, even without any construction experience. Building a whole earth house from scratch is more complex and requires more planning and technical understanding – for that, I'd recommend working with experienced professionals.

Question 5

Why is indoor air quality so important?

Accepted Answer

We spend up to 90% of our time indoors – and according to studies, indoor air is often more polluted than outdoor air. Conventional paints, floor coverings and insulation materials can release volatile organic compounds (VOCs) that cause headaches, allergies and breathing problems. Clay and lime, on the other hand, are breathable, regulate humidity and bind pollutants – for an indoor climate you can actually feel.

Question 6

What is the difference between clay plaster and lime plaster?

Accepted Answer

Both are natural, chemical-free plasters – but with different strengths.

Clay plaster regulates humidity particularly well, is antistatic and binds odours. It's ideal for interiors, especially bedrooms and children's rooms.

Lime plaster is naturally alkaline and therefore antimicrobial and mould-resistant. It hardens by absorbing CO₂ and becomes more stable over time – ideal for damp rooms, basements and exterior walls. Both can be applied yourself and are fully recyclable.

Question 7

What are natural wall paints and how do they differ from conventional paints?

Accepted Answer

Natural wall paints are based on raw materials like clay, lime or casein (milk protein) – without synthetic solvents, plasticisers or preservatives. They have significantly lower VOC levels than conventional paints and are breathable: walls can regulate moisture, and mould has less chance to take hold. They're also biodegradable and barely affect soil or water. At Earth to Wall we work with three tried-and-tested natural paints: clay paint, limewash and casein paint.

Question 8

Is earth building more expensive than conventional building?

Accepted Answer

It depends on the context – and especially on the balance between labour and materials.

With earth building, materials are often very cheap: earth is locally available, sometimes even free from your own excavation. However, the labour input is higher – many techniques require more handwork than industrial building materials.

With conventional building it's the opposite: industrially produced materials like concrete, bricks or insulation are more expensive to buy, but can be processed faster and with less labour.

Anyone who self-builds or works with a community can save significantly with earth building – because the expensive component (labour) is replaced by their own effort.

Question 9

Which earth building technique is best for beginners?

Accepted Answer

For getting started I recommend: applying clay plaster (easy to learn, immediately visible results), mixing and applying natural wall paints (very accessible, no prior knowledge needed), or building a clay oven (cob technique, ideal as a first project). For larger building projects, you can start with wattle and daub as wall infill or make your own clay bricks – both techniques are well documented and suitable for self-builders.

Question 10

How do I protect clay walls from moisture?

Accepted Answer

The most important protective measures: a sufficient roof overhang, a solid, moisture-insulated foundation, and a protective exterior render of lime. Inside, a clay (fine) plaster is usually sufficient. Clay walls should not be permanently exposed to direct rain – but with the right protection they are very robust. In humid climates, lime plaster is often preferred as the outer layer.

Question 11

Can I learn earth building myself – without a course?

Accepted Answer

Yes, a lot can be learned from good guides, tutorials and videos. At Earth to Wall, an online school is currently being developed for renovating with clay and lime – with step-by-step courses on topics like wall paints, plasters, earthen floors, partition walls and more. The goal: after the courses, you'll be able to renovate or upgrade your home independently with clay and lime.

For more complex projects like new builds, I'd recommend complementing this with a workshop or working alongside experienced professionals – it saves time and avoids typical beginner mistakes.

Question 12

Is earth building sustainable?

Accepted Answer

Yes – clay is one of the most sustainable building materials there is. It's locally available, requires minimal energy to process (no kilns, no chemicals) and is fully recyclable: clay components can simply be soaked in water and reshaped. Compared to concrete, whose production accounts for roughly 8% of global CO₂ emissions, clay's carbon footprint is negligible. On top of that, its natural climate regulation reduces the energy needed for heating and cooling.

Question 13

What is tadelakt and what is it suitable for?

Accepted Answer

Tadelakt is a traditional Moroccan plastering technique: lime plaster is polished and sealed with black olive soap – the result is a naturally waterproof, silky gleaming surface without any chemicals. Tadelakt is suitable for bathrooms, showers, kitchens, sinks, and outdoor areas – wherever water and aesthetics meet.

Question 14

How long do earth buildings last?

Accepted Answer

A very long time – if built and maintained correctly. Many earth houses have stood for hundreds of years. The UNESCO World Heritage Site of Ait Benhaddou in Morocco is a prime example: a clay city that has been inhabited for over 1,000 years. In Germany and Europe there are numerous half-timbered houses with clay infill from the 16th and 17th centuries that are still in use today.

Earth Building – All the Answers

Still have questions?