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FAQ: Do rammed earth walls wash away in the rain?

Mmofra park children's wall, Accra, Ghana

Rammed earth has been around for thousands of years, in fact, rammed earth can be traced back 8000 years.

However, with the turn of the industrial revolution rammed earth started to become less popular due to newer construction methods.

Today Rammed Earth is going through a revival, with the current climate crisis builders and architects are increasingly looking at ways to build sustainably.

With more research into rammed earth, advanced technology, and engineering the process of rammed earth has become a lot more efficient than what ancient civilization used.

With the new interest in rammed earth construction, comes many questions about this unconventional Eco-building method.

Below are frequently asked questions commonly asked when it comes to rammed earth construction.

How much does it cost to build with rammed earth?

This question is relative and depends on how much your labor cost is in your country.

Let's assume you have volunteer labor and just buying materials for a single-story 2 bedroom home, compared to block or concrete construction it is cheaper.

If you are building unstabilized earth walls, you save money on cement, however, if you are stabilizing your walls normally 3-10% is added.

There is still a cost saving here because with concrete/ block construction around 20-30% cement is needed.

Rammed earth walls are also load bearing so there isn’t a need for reinforcement, saving you additional cost.

If you are very lucky you may be able to find all the materials on your land, so then you won't need to purchase materials saving you even more.

Rammed earth construction itself doesn't need any heavy equipment either, you can purchase basic tools from your local hardware store.

Also when rammed earth walls are done, they are done, so no need to paint or plaster so you save cost on that also.

However, please note that rammed earth construction is extremely labor intensive, and if you are paying for labor, this can take a chunk of your budget.

Will rammed earth walls wash away in the rain?

No, this will not happen, in fact, rainfall and sunshine help the walls to become stronger over time once it is fully cured.

Rammed earth walls are designed to withstand various environmental conditions, including rain. While rain can impact the surface of rammed earth walls, particularly when they are newly rammed and not cured, it generally does not wash them away.

The density of rammed earth walls, along with the right soil mix and stabilization techniques, will ensure the walls' durability.

Additionally, proper design considerations such as effective drainage systems and protective finishes can further enhance the walls' resistance to rainwater erosion.

Tallest rammed earth building in Weilburg Germany built in the 19th century

Will rammed earth walls crumble over time?

Definitely not, rammed earth walls have proven to be bulletproof in fact ancient civilizations used them as a defense from enemy attacks.

When properly constructed and maintained, they can withstand the test of time without crumbling. The key to their strength lies in the precise mixture of soil, stabilization, and adequate compaction during construction.

Regular maintenance, such as inspecting for any signs of deterioration and addressing them promptly, can help prevent potential issues and ensure the walls remain structurally sound for many years. While factors such as natural settling, seismic activity, or extreme weather conditions could have an impact, with proper design, construction, and maintenance, rammed earth walls have demonstrated remarkable resilience and can maintain their strength over an extended period.

Can rammed earth go up multiple floors?

Rammed earth construction can indeed be used to create multi-story buildings. While rammed earth walls are typically thicker compared to conventional construction methods, they possess sufficient strength and load-bearing capacity to support multiple floors.

The key consideration when designing multi-story rammed earth structures is ensuring the walls are properly reinforced and stabilized to handle the increased vertical loads. This may involve incorporating additional reinforcement elements such as steel or bamboo within the walls, as well as implementing appropriate foundation designs and structural systems. It's crucial to engage experienced architects, engineers, and construction professionals who specialize in rammed earth to ensure the design and construction meet the necessary structural requirements for multi-story buildings.

Dot Ateliers Gellery, Accra, Ghana.

How do you get the colors in rammed earth walls?

The colors in rammed-earth walls are from the natural pigments that are already in the soil. In order to get different colors, you can ram in layers with different soil colors or you can mix different soils to get the color you want.

In order to achieve other colors that are not typically associated with soils, you can add iron oxide pigments to the soil.

But please note that in order to achieve a rich color you need to add a lot of pigment which will give you a nice vibrant finish, but at the same time it takes away from the natural nature of rammed earth walls.

Also when adding oxide pigments, with weathering the pigments fade over time, so if you can get natural pigments it's better.

How do you get rammed earth walls to be smooth?

Achieving a smooth finish on rammed earth walls requires attention to detail and careful execution throughout the construction process. The initial step involves meticulous soil preparation, selecting a well-balanced mixture of clay, sand, and gravel that allows for proper compaction. Controlling the moisture content is crucial, as the soil should be adequately moist but not overly wet to ensure optimal compaction and prevent surface imperfections.

Layering the soil mixture in small increments and compacting each layer thoroughly with consistent pressure helps achieve a uniform and dense wall surface.

Rammed earth Yoga studio by Invisible studio, U.K

What happens when cracks appear in a rammed earth wall

When cracks appear in rammed earth walls, it is important to assess the severity and underlying causes to determine the appropriate course of action.

Cracks can occur due to various factors such as the settling of the foundation, fluctuations in moisture content, thermal expansion, and contraction, or structural movement.

Hairline cracks are common in rammed earth walls and are normally nothing to worry about if they don't expand. Small hairline cracks are a normal part of the curing process and can often be expected.

However, if cracks become wider or show signs of significant movement, it may indicate a more serious issue that requires attention.

It is advisable to consult a professional experienced in rammed earth construction to evaluate the cracks and provide guidance on the necessary repairs. Depending on the severity and cause of the cracks, repair methods can range from minor cosmetic fixes, such as filling with compatible materials, to more extensive measures like reinforcing with additional materials or addressing underlying structural issues.

What's the difference between stabilized and unstabilized rammed earth?

The critical difference between stabilized and unstabilized rammed earth is the use of additional materials such as cement or lime to enhance the structural properties of the walls.

Unstabilized rammed earth refers to the traditional method where only natural soil, such as a mixture of clay, sand, and gravel, is used without any added stabilizers.

In this case, the soil relies on its inherent properties for cohesion and strength. On the other hand, stabilized rammed earth involves the incorporation of stabilizing materials such as cement or lime to enhance the wall's durability, strength, and resistance to moisture.

Stabilizers help bind the soil particles together and improve the load-bearing capacity of the walls. The use of stabilizers can offer additional benefits, such as increased resistance to weathering, improved crack resistance, and enhanced structural performance.

Unstablised rammed earth Library by Archi Fair, Nsutam Ghana

Can rammed earth walls be painted?

Yes, rammed earth walls can be painted to add color, protect the surface, or achieve a desired aesthetic.

Before painting, it is essential to prepare the walls properly. This typically involves cleaning the surface to remove dirt, dust, or loose particles. If there are any imperfections or cracks, they should be repaired and filled using suitable materials compatible with rammed earth.

It is recommended to select a paint that allows the rammed earth walls to breathe and does not trap moisture within the material. Regular maintenance may be required to touch up the paint over time due to weathering or wear.

How strong is rammed earth

Rammed earth walls are very strong. The strength of rammed earth walls can vary depending on factors such as the composition of the soil mix, the level of compaction achieved during construction, and the presence of stabilizers.

When properly designed and constructed, rammed earth walls can possess significant compressive strength, typically ranging from 1.5 and above, in fact, we have constructed a stabilized earth wall that achieved 8MPA.

This strength is comparable to or even surpasses that of traditional masonry materials such as brick or concrete blocks.

Check out our rammed earth online course and e-book.

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