Building green includes the materials you use to construct a home or outdoor feature like a patio. The ideal green material is found locally and it can be replaced easily. So you can imagine that when they were building the Great Wall of China (Jiayuguan Wall shown here via Wikipedia), the most available material was dirt which is the basis for rammed earth construction.
Here's an article on building the Great Wall of China, and how they varied the materials used based on where they were building. Fascinating because we don't think of the wall in the desert.
Building materials used to construct our homes today include cork and bamboo because they grow quickly, making them a sustainable material. The downside is the ecological impact of shipping these materials to your construction site. We know homes in the US were once built from local materials like logs for log cabins, sod in the midwest and today's brick homes remain popular in areas of the country that don't have an abundant supply of trees.
What is Rammed Earth?
There's a type of material that is found almost everywhere but we don't think of it as a building material. If you’re looking for a unique green material to build your patio, rammed earth is an option worth researching.
Rammed earth construction is perhaps the earliest form of construction in many cultures because dirt is readily available and sturdy when mixed with other natural materials to give it strength. In fact houses built of earthen walls also benefit from heat retention, when the thick wall capture and store solar energy. These walls create an indoor environment that is cool in summer and warm in winter.
Rammed earth construction became popular in the US during the Depression, and it’s gaining popularity again with the emphasis on building green. Rammed earth construction is especially popular in the Southwest part of the US where adobe has always been popular. The same techniques are used in Australia, and while not everyone is building a house with this technique, they are building walls, wine cellars and patio floors with earth.
You'd be amazed at the different types of structures people are building using these techniques. The photo above is a greenhouse wall from Clifton Schooley & Associates, Rammed Earth Designers & Builders, located in Canada! Here are some great ideas if you're ready to try this green approach to building and you'll want to visit their websites for more photos.
- Houses using rammed earth columns for structural support, walls too (take a peak here).
- Smaller structures like that a gardening shed or carport?
- What about a greenhouse … making it all truly green!
- For landscaping, consider walls and raised gardening beds.
If you still don't believe you can truly build using dirt, then you'll also want to look at what the folks at RammedEarthConstructions.com (they're in Australia) have been building. Their portfolio includes lots of commercial buildings like the art gallery shown here, plus amazing houses you'd never know were made from “dirt”. So if you like these photos, visit their website to see lots more …
How Do You Build Rammed Earth Walls & Floors?
First let's look at how rammed earth walls are built. The process is a lot like poured concrete foundations as they both use wood forms during the construction process. The walls are built in layers, each one being compressed before the next layer is added. The only difference with a rammed earth floor is there are fewer layers.
Many people assume that a floor made of dirt will be dusty. That isn't true when this flooring is installed properly. Just like sealing a deck, a rammed earth floor should be coated with a sealer like linseed oil or a blend of oils. This coating makes the floor's surface easy to maintain by sweeping and mopping, just like cleaning a tile or wood floor.
Todays' professionals make rammed earth floors with clay-based soil, sand, water and chopped straw and put linseed oil on top. Every few years it is recommended that the floor is repaired with its native clay material and then resealed with oil. Historically, many different cultures have used rammed earth construction with different forms of sealer. In rural Japan, people used bath water containing oils from their skin, Indian cultures used ghee (clarified butter) and Southwest Americans have used oxblood mixed with dirt for a durable surface.
The Pros and Cons of Rammed Earth
There are many benefits to building a rammed earth patio. Rammed earth is a sustainable material that you can find locally, enabling you to build green. It can be made of 100% natural materials from the land it is built on, and doesn’t produce harmful toxins when it burns. It is nearly as strong as concrete, yet when things are dropped on the ground the floor gives a little so they don’t break.
Making tile or slabs out of rammed earth requires forms for shaping and either a hand-operated compactor or a mechanical one. Virtually any finish you would expect to find for concrete or brick can be applied to rammed earth patio flooring. Any natural color can be used for rammed earth installations, and even designer colors can be found. You can expect rammed earth floors to feel more like leather than concrete, and be just as easy to dent and scratch as a wood floor.
Since rammed earth is a niche material new to the popular market, it may be difficult to find an experienced professional where you live. For DIY homeowners who are adventurous, you might want to try building your own rammed earth floor but do your research and don't be afraid to get help from the experts.