The Future of Cob Houses: Innovations and Advancements

A photograph of a cob house still under construction with the door and window openings formed but no windows or doors yet fitted. The words "The Future of Cob Houses: Innovations and Advancements" are written across the top, and "The Future Is Bright" is written in colorful letters beneath.

The world of sustainable construction is increasingly seeking ways to reduce our environmental footprint.

Cob houses represent one of the most attractive options in terms of energy efficiency and cost-effectiveness. However, with modern technologies emerging rapidly and consumer tastes changing quickly, what is the future of cob houses?

Currently, the construction industry classifies cob as an alternative building material. This is because it’s not common in mainstream construction.

However, with the construction industry accounting for 38 percent of energy-based carbon emissions, there is renewed interest in cob due to its low carbon footprint.

In the rest of this article, I’ll discuss the future of cob houses. I’ll cover innovations and advancements in cob construction and the potential for widespread adoption.

By exploring these topics, I hope to provide insight into how cob could shape the future of sustainable building.

Trends in Cob Construction

A photograph of a cob wall with a graph overlain showing an upward trend.
Cob construction waned in the twentieth century but is making a comeback thanks to increased environmental awareness.

Before tackling the future of cob houses, let’s recap the trends in cob construction. This will help you understand how this building technique has been evolving to the present times and what to expect in the future.

The Rise and Decline of Cob Construction

Cob has been utilized as a building material for millennia, dating back to the 11th and 12th centuries.

Being a material of abundance, cob structures are found all over the world, including in Africa, Asia, Europe, and America. However, cob fell out of favor in many parts of the world during the industrialization era which led to the development of modern building materials.

The advent of mechanized production of building materials ensured uniformity and quality, a feature that most consumers fell in love with. Consequently, high demand for such building materials paved the way for mass-scale consumerism.

With the aid of machines, raw building materials were refined to remove all imperfections, leading to a mechanized aesthetic and high efficiency.

On the other hand, natural building materials like cob became associated with inefficiencies and imperfections. Consequently, they were viewed as inferior building materials, only suitable for rural projects.

The Revival of Cob and Other Natural Building Materials

In the 1960s, the awareness of the impact of building materials on the environment marked a radical turning point.

As people began to understand the effects of industrialized building materials on the environment, there was a renewed interest in natural materials like cob.

The “Environmentalism Movement” of the 70s and 80s further highlighted traditional construction methods such as cob and their environmental benefits.

The escalation of the Environmentalism Movement gave rise to the ‘sustainability agenda’ in the 1990s, reigniting interest in natural building materials like cob.

The resurgence of cob construction is evidenced by the development of many cob structures in the 20th and 21st centuries.

A photograph of the Cob Castle in East Devon as featured on the Daily Mail website. It comprises two large cob-built living areas connected by a glazed walkway. The structure is capped with a sweeping green roof that dips in the middle above the single-story walkway between the two-story living areas either side.
Cob Castle in East Devon is one of many modern and stylish buildings that have been built from cob in recent times. Image courtesy of Daily Mail.

For instance, In England, pioneers like Kevin McCabe in Devon and Ianto Evans and Linda in Oregon, have been instrumental in popularizing cob structures.

The ancient cob construction technique that involves mixing clay, sand, and straw remains unchanged.

The technology has been enhanced over the years with modern construction tools, such as tamping rods and rubber mats, to compress the material.

Innovations and Advancements for the Future of Cob Houses

Cob’s revival as a building material is still in its infancy. We keep learning about how to improve our cob building efficiency in terms of the following:

  • Soil and aggregate mixing.
  • Using a wider range of soil types.
  • New cob techniques, applications, and designs.

That said, the following are the innovations and advancements expected in the future of cob houses:

Improved Engineered Modular Cob

All along, eco-conscious builders have relied on in-situ cob for building. This material has drawbacks, such as poor thermal and insulation efficiency.

The advent of cob blocks will provide an engineered modular solution designed to provide better engineering cob standards and high thermal efficiency.

For instance, according to British Standard 5628, a cob wall of 400 mm (15.75-inch) depth was designed and built as conventional masonry. The wall displayed excellent compressive strength and minimal shrinkage, illustrating the future possibility of using cob in mainstream construction.

Improved Insulation

Among the drawbacks of cob is its poor insulating capacity.

With an R-value of 0.22 per inch of thickness, there is room for innovation and improvement.

Although many viable insulation materials like hemp, sheep’s wool, and fiberglass can be incorporated into cob walls, one challenge exists — moisture accumulation within the walls.

The best way around this is using a double wall system by incorporating an exterior wall made from a high R-value fiber mix like straw bale. This is the future cob insulation approach advocated for at This Cob House.

A workshop where cob walls are being made for testing. In the foreground are a dual cob wall system with an outer leaf for strength and a less dense inner layer for insulation.
A dual cob wall system with an outer leaf for strength and a less dense inner layer for insulation. Image courtesy of MAKE IT LONDON LTD.

Regional Diversification

As more people become aware of the sustainable nature of cob houses, the technique will be adopted in different regions. These regions vary in climate, geography, and cultural conditions, calling for a diversified cob building technique.

Therefore, going into the future, strategies will be developed to ensure cob construction aligns with the specific region.

For example, strategies will be developed to strengthen cob houses in areas with high seismic activities.

Moreover, sufficient insulation will be incorporated into cob walls in colder climates and cob amendments for areas lacking good quality straw and sand.

Heightened Demand for Cob Building

There will be heightened demand to incorporate cob into the mainstream building industry. This is evidenced by the adoption of a cob code building appendix by the International Code Council.

The adoption of Appendix AU on Cob Construction in 2021 opened a new world for this building technique.

With this cob code in place, many people will be confident to build with cob. Consequently, cob will eventually be listed as one of the mainstream building materials to enhance sustainability.

Automated Mixing

A Whiteman masonry mixer is being used to mix cob inside a cob building. It's a red machine with small wheels, similar to a concrete mixer except with paddles that move the mixture around inside the drum instead of the drum itself rotating.
Using a Masory mixer is one way that cob can be mixed mechanically. This saves a lot of effort but doesn’t do all of the hard work for you. Image courtesy of paul wheaton, missoula, MT.

Currently, cob is mixed by hand and feet. In some cases, people use shovels to mix cob.

The traditional approach to cob mixing is not efficient. It can be challenging to attain the required aggregate proportion for sturdy and durable cob.

However, continued testing and advancements in technology will lead to the creation of automated cob mixers for accurate clay, sand, water, and straw proportions.

Improved Finishes

Although cob walls are beautiful in their natural state, they’re highly susceptible to erosion due to rain.

While many finishes are used in traditional houses, most are unsuitable for cob walls due to their impermeable nature. Cob houses require permeable finishes to prevent moisture accumulation.

Besides clay and lime-based plasters, the continued innovation in coatings and finishes will eventually create a manufactured finish suitable for cob walls. The finish will be suitable for protection against moisture, UV radiation, and wear and tear.

Final Thoughts

The future of cob houses is a bright one. Continued innovation and the push for sustainable construction are working in favor of cob construction.

With modern technology and design integration, cob houses are becoming even more efficient, comfortable, and durable. Consequently, many homeowners and builders are bound to adopt cob as a viable building material.

Before you leave, here is a guide on how to use a reclaimed wood mantel for your fireplace, which could create the perfect centerpiece for your cob house living room.

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