“Dirt is the original DIY material. In cultures all over the world, people have used earth to fashion everything from bowls to buildings. We know this because so many earthen homes are still around, including buildings hundreds and even thousands of years old. In recent decades, interest in earth construction has risen. What follows are some of the pros and cons of the different types of earthen building, including adobe, cob, compressed earth blocks and clay-slip straw, and some practical tips on things you may want to try as well as those you’ll want to avoid.
Earthen Home Basics
Some basic features and practices apply to most earthen building types. First, the old adage: Give your buildings a good pair of boots and a hat. That means lifting your earthen walls up away from water on a solid foundation and covering them with big overhangs.
I’m a fan of outdoor rooms, so I prefer large patio overhangs all around, except for the south side of the building if we need passive solar heat gain in the winter. To prevent water damage, keep earthen walls covered during construction. A sensible approach in wet climates is to build the roof first on a post-and-beam structure, and then infill with bricks, cob or clay-slip straw.
Second, dirt isn’t insulation. Light, fluffy and airtight assemblies prevent heat flow; massive, dense ones do not. Some people don’t get this. I think the confusion arises because of a unique feature of the most common earthen building climate: hot and arid. In such regions, exterior temperatures tend to fluctuate above and below desired interior temperatures (hot during the day, cold at night). Thick-mass walls can act as an effective form of dynamic insulation. In all other climates, in my view, earthen materials aren’t appropriate for exterior wall systems if your goal is to build the most energy-efficient building. They instead should be used inside the insulated envelope as interior walls, floors and plasters to add mass, soundproofing and beauty to the building.
Third, earthen building is not easy, simple or cheap. Dirt is heavy, and you need to move a lot of it around to build. That’s not easy. Anything heavy that has the potential of falling on your head needs to be taken seriously. As for cheap, a big plus of earthen building is definitely that much of the material can often be found on site and is ubiquitous and inexpensive. But earthen building is labor-intensive, so what you save in materials, you may pay back in hard work. Of course, much of it may be slave labor (i.e., you), but to make an apples-to-apples comparison with conventional approaches, you have to value that time. I could make a free building out of gold if the gold were salvaged and the labor were unpaid.
Finally, the best earthen building approach is one that has a history in your area, because that means local expertise is available, and problem solving and code approval will likely be easier. Being a novice without elders to guide you along can be a lonely, difficult enterprise. Building is hard, serious work — wonderfully rewarding if done right and potentially calamitous if done wrong.”
Read more at the source: Mother Earth News (thousands of free articles)
Photo: Bill Steen at Canelo Project
Be sure to read to the end of the article where they give their advice on the best finishes for earth floors and earth plaster.
Google Site Search is a very useful utility.
In fact, it is possible for your web designer to install a search box that uses Google Site search to search just this site instead of whatever search utility you are currently using.
In any case, I find 811 hits on this blog for entries that contain both words, “Scoria” and “Foundation”. Keep in mind that this search function also includes searching the comments as well.
Type the following into Google to perform the search I just described:
site:https://naturalbuildingblog.siterubix.com scoria foundation
Hope this is helpful to some trying to find specific information.
What do you think about a scoria foundation? As in, a rubble trench foundation with the rubble being scoria rather than gravel. If the scoria were strong enough to support the structure, you’ve got a self-insulating, self-draining foundation!
Yes, that’s what we’ve been recommending for years if you have access to scoria. Search our site and you’ll find 10-20 references to this technique, plus it’s covered in my earthbag ebook. As I’ve said before, building with scoria is one of the best aspects of building with bags. This is how Kelly Hart built his home and how dozens or hundreds of other people have built earthbag homes. It greatly reduces labor and provides superior insulation.
Tip: Our site is so big now that the built-in search engine is becoming inefficient. Use a major search engine with “natural building blog” in the search phrase along with the keywords you’re looking for such as scoria or lava rock. This will save you an hour of scrolling through unrelated articles.
Also do a search for “scoria casita” — a great little structure built near Taos made entirely of scoria bags. That guy shows all the various reinforcing techniques.
One important note about wide porches.
I have worked in some areas where tax assessors count attached porches as square footage of the home. This doesn’t happen everywhere, but it does in some places.
Every place I have found that does this, allows the construction of an unattached gazebo, and it is either unappraised, or is appraised for very little.
This does NOT have anything to do with whether the area is covered by building codes or not. It’s simply a tax assessment issue.
Large wrap around porches can easily double, and often triple the size of the home. If that space is getting taxed at the same rate as the interior space, it can become extremely expensive.
It is wise to know how your local tax laws are applied. If you encounter such a situation, look into building an UNATTACHED gazebo or shade structure right next to your home. It can serve the same purpose as a porch and cost DRAMATICALLY less in taxes.
Yes, there are some very weird property tax laws out there. Educate yourself about your local laws, and don’t get shafted on your tax bill.
Thank you sir. As awful as my day has been, I’m really surprised that only that mistake jumped out at anyone. Was just told a few hours ago that the settled land deal just got blown out of the water !! Only have 36 days to figure out this mess. I really, really want to sit on my wide shady porch surrounding my alternative built home…facing that lovely pond.
Hi Bill, Most of your advice is good and solid. But the last piece needs to be ad minded. There are too many areas that do not have a history of alternative building. SOMEONE has to start it in those areas. If only tried by those who can find a history in that local ,,,,then alternative will only be in those few areas. Those of us who do not live or can move to those areas need to find a way to get it adapted and used in their area.
I am trying hard to do that for the Northwest area of Louisiana. Sadly, straw bails are out due to the humidity. But I am hoping, with the help of a West Coast Architect who bothered to carry a Louisiana licenses, to get a home started in this area in the next few years.
Please keep us posted. And by the way, I think you meant to say “or can’t move to those areas…”.
I love those wide porches. Like I said the other day, they protect the walls and provide lots of shady outdoor space.