Building a Home from Poured Earth
There seems to be a growing interest in earth-based buildings these days. There are several possibilities for the attraction – earth-based structures are eco-friendly, the building material is plentiful, and as the toxic nature of conventional building materials becomes more well-known, many people prefer the non-toxic nature of natural building materials. Poured earth is one type of earthen construction that is enjoying a resurgence.
What Is Poured Earth?
It sounds like a fancy term for mud, but it’s more than that. Like concrete, poured earth uses a combination of aggregate (hard, inert, binding material) and dry cement. Many people confuse the terms “concrete” and “cement” – they are not the same. Cement is a component of concrete, not vice versa.
When concrete is mixed, the aggregate is sand and gravel, which is mixed with dry cement and water. Poured earth uses soil as the aggregate, which is then mixed with dry cement and water. Thus, poured earth is somewhat akin to concrete (not cement).
The soil used in poured earth structures needs to meet certain specifications, which require testing to discern. If you are planning to build using poured earth and your soil does not meet the specifications – say it’s too high in clay – then soil amendments, such as lyme or magnesium oxide can be added to bring your soil up to specification.
How compatible your soil is for poured earth will determine how much cement you will need to mix in – the less clay, the less cement is needed. Mixing in a material known as flyash can reduce the amount of cement you need.
What Else Do You Need?
* You will need some way to pour the earth as you would concrete, such as a traditional cement mixer or concrete pump. Try to rent or borrow one from a local construction company.
* Frames are necessary to hold the poured earth walls as they dry. You can use concrete frames, steel, or wood.
* Plaster, cob, or other finishing material will be needed for indoor and outdoor walls.
Is It Expensive?
Initially, yes, it is a bit more expensive than conventional construction. At this point, poured earth structures are customized buildings, which makes any project more expensive. Bear in mind, however, that poured earth buildings are inexpensive to maintain (more on that below). Also, as poured earth becomes more widely known and utilized, the cost will likely go down as standard types develop.
What Are the Advantages of Poured Earth Buildings?
* Poured earth buildings are extremely durable, comparable to concrete.
* The thick walls of poured earth create a peaceful interior.
* Poured earth is free of chemically-treated wood, synthetic insulation, formaldehyde, and other toxic building materials.
* The durable nature of poured earth means that it is highly resistant to the wear and tear that occur in typical homes. It is very low-maintenance.
* Heating and cooling are aided by the radioative effects of the earthen walls, which have “inherent thermal mass.” They absorb heat and release it gradually, making the internal temperature inexpensive to maintain and far more constant.
* Fast construction is another advantage of poured earth buildings.
Once you construct a foundation, the frames are erected and filled with the poured earth mixture. For extra insulation, some builders will construct a second wall with a space between the two, which is then filled with eco-friendly insulation. After the walls dry and “cure,” you can finish them with plaster or cob (a mix of mud and straw). Then the interior and exterior walls can be painted as you like.
Image credit: www.greenhomebuilding.com
