Welcome to what I hope is the beginning of your journey to a cheap, sustainable and long lasting building, whether it’s to be your home, workplace or like me, a shed at the bottom of the garden.
When I first stumbled upon rammed earth, I was no eco warrior. The most I ever did to save the planet was recycle my empty beer cans. But building with earth turns out to be a very sustainable thing to do...
|Posted by Michael Thompson on February 15, 2012 at 10:20 AM||comments (0)|
Now, you need to be let in on my secret weapon... none of this would have happened if it hadn’t been for SID.
SID (Soil Improvement Device) is a contraption that I had already built prior to even hearing of rammed earth. He came about because we had a problem. We wanted to grow vegetables in the garden but found that our topsoil was contaminated with brick rubble, rope, plastic and no end of glass. We couldn’t grow in that, so SID was conceived.
SID screens the soil and ejects particles over 25mm down the top shoot and then a second lower screen of 12mm separates particles between12mm and 25mm down another lower shoot. The earth particles under 12mm go straight through SID into the wheelbarrow and are returned to the raised beds for our crops to grow in.
When I started to look into rammed earth building, I soon realised that one of the main hurdles you need to jump is soil screening. SID can process around one tonne an hour (if you have two wheelbarrows and two pairs of hands), so it didn’t take too long to sort out the 39 tonnes to build the Eco-Shed.
I already had around 26 tonnes of subsoil from the excavations from the shed’s footings and the other13 tonnes came from a building site six miles down the road. All this subsoil was processed through SID. The total cost to build him was just £45, including the power unit - a £25 drill from a large DIY chain. Keep your receipt, as they only seem to do about 13 tonnes before the inevitable happens! I am sure that many of you could improve on my design, especially the power unit. I have seen some examples based on SID that use a jigsaw to cause a vibrating effect to process the material. Even better would be a powerful motor – the kind you get on concrete mixers - with a speed controller.
All the big stuff such as brick rubble and stones, which comes down the top shoot, can be re-used as hardcore for your subfloor and the smaller stones from the lower shoot we used for pathways around the garden. Everything in the barrow is below 12mm and this is what I used for my rammed earth walls.
I have since built a new soil sieve which is a better design as it puts less strain on the motor.
Finally, don’t forget the safety goggles, have fun and good luck!
|Posted by Michael Thompson on February 12, 2012 at 3:45 PM||comments (0)|
You will need some type of mixing machine; I used a regular cement mixer, which I bought second hand for around £100. These mixers can handle nine shovels of earth at a time. This is a good quantity for ramming by hand; it takes around 15 to 20 minutes to get the earth to a suitable dampness. It also takes around the same amount of time to ram this quantity by hand, so if you have a two-person team you will be working to the maximum efficiency.
You could use a rotovator instead, if you have the floor area to operate it. These are handy if you need to mix bigger volumes of earth. If you plan to use pneumatic ramming then you may well need to get one of these, as mechanical ramming can be up to twice as quick than manual ramming. Second hand rotovators can be picked up for around £100.
When the earth is processed, it usually requires the addition of water which should be blended slowly and evenly throughout the mix. If you plan to use rainwater then you will need to use a watering can with a sprinkler rose, if you use mains water then get a hosepipe gun with a sprinkler setting.
Do not underestimate the power of the rubber bucket! You will need to transport your materials around the build site and they are invaluable in the rammed earth construction process. They cost around £4 but last a long time. You will need about six of them.
Wheelbarrows are also invaluable. You may well already have one knocking around but you will need at least two. They are quite expensive at around £35, but most people have one that they rarely use, so ask your friends and neighbours if you can borrow theirs.
When it comes to the matter of ramming, you have two options: mechanical or manual. I originally intended to go down the pneumatic route; I managed to find a couple of secondhand pneumatic rammers for £46 on eBay, one worked and the other had seized up. Then I went to look at a trailer compressor at a local farm that was up for sale. They wanted £650 but when it was started up I couldn’t believe how noisy it was, so I didn’t buy it. Instead, I went to a local tool hire depot where they had new ones for rent. However, when they started one up for me, it was even louder! Being overlooked by five other houses, I realised that I would not be very popular with my neighbours if I used the pneumatic method.
So, I went down the manual ramming road. It takes around twice as long to compact the earth this way, but it’s a lot quieter. Get a hand rammer with a long handle (ideally, as tall as you are); the shorter ones may well look easier to use but your back will tell you otherwise at the end of the day! Look to pay around £20.
Most of the other tools you will need are readily available from your local hardware shop and you may well own many of them already or be able to borrow them from friends and neighbours. You will need a couple of builders shovels, some spirit levels and an adjustable spanner to get your form work set up straight, a lump hammer for general bashing jobs and a scraper to keep the bottom of your rammer clean. Finally, don’t forget your gloves and goggles!
Get some trestles to enable you to work safely at height as your building grows. These are quite expensive to buy new at around £30 each but look out for second hand ones. I got hold of a dozen for just £26. I had to oil them up and some were a bit bent, but on the whole they served me well and I could easily sell them and recover my money, as I could with much of the other equipment I used.
|Posted by Michael Thompson on February 10, 2012 at 12:20 PM||comments (0)|
Evidence of the early use of rammed earth has been seen in Neolithic archaeological sites of the Yangshao and the Longshan cultures in China, along the Yellow River and dating back to 5000BC. By 2000BC, the use of rammed earth architectural techniques was common for walls and foundations in China.
In the 1800s in the United States, rammed earth was popularised by S W Johnson. For example, it was used to construct Borough House Plantation and the Church of the Holy Cross in South Carolina, which are two National Historic Landmarks in the United States. Constructed in 1821, the Borough House Plantation complex contains the oldest and largest collection of 'high style' pise de terre (rammed earth) buildings in the United States. Portions of the main house were constructed using this ancient technique, which was introduced to the country in 1806 through his book Rural Economy.
During the 1920s and through to the 1940s, millions of dollars were spent by the United States Government and several western universities, studying rammed earth construction. South Dakota State College carried out extensive research and built almost one hundred weathering walls of rammed earth.
Over a period of thirty years of exploration, the college researched the use of paints and plasters and in 1945 Clemson Agricultural College of South Carolina published their results on rammed earth research in a pamphlet called Rammed Earth Building Construction. In 1936, on a homestead near Gardendale, Alabama, the United States Department of Agriculture constructed an experimental community of rammed earth buildings with architect Thomas Hibben. The houses were built at a very reasonable cost and sold to the public, along with tracts of land sufficient for a garden and small livestock plots. The project was a success and provided valuable homes to low-income families.
Interest in rammed earth declined after World War II when the cost of modern building materials dropped. Rammed earth was seen as primitive in the face of new technology and heavily dependent on labour. Soil as a building material often meets with opposition from many contractors, engineers,and tradesmen who are unfamiliar with earth construction techniques. Often the modern method of construction seems easier. Profitable investment is uncertain, so rammed earth construction is frequently neglected in modern building cultures.
|Posted by Michael Thompson on February 10, 2012 at 11:10 AM||comments (0)|
The rammed earth method is a very clean process that produces smooth, solid walls that are plenty strong enough to fit windows and hang doors in the same way as today’s modern buildings. I decided to regard it as a challenge, a test of character, a chance to avoid the heavy cost to the environment of building with bricks; but most of all, I realised that it was going to be dirt cheap.
Before we get going, let me say this... I didn’t set out to build with earth in order to save the planet; rather I built with earth to save a packet! Things are different now, but back then it was the money meaning of the phrase Eco-Build that convinced me. It just turns out that when you strive to save money, you usually end up saving the planet by accident.
This is mostly down to the mind set you need to adopt... Using my budgeting method, Pound-Zero, you will be amazed at how you can avoid spending money by just believing that you haven’t got any to spend. Sometimes you will get things for nothing by re-using something you already have or by asking friendsand neighbours if they have what you need. Sometimes you will have to spend something to enable you to go forward, but always take the time to search out an alternative way, or get ten quotes for materials instead of just three. You will be surprised how half an hour on the phone or the Internet can keep your costs down to earth. Another potentially big expense can be the disposal of waste. Skips are expensive things, so if you can avoid waste then you will be sure to avoid costs. By planning ahead, I managed without a single skip or trip to the local dump. Most of the waste that was created, I managed to re-use within the building itself as subfloor material and only minimal amounts went into my domestic rubbish bin.
When I embarked on this journey, I hadn’t visited any existing rammed earth buildings or attended any courses to learn what to do and when to do it. I just took the plunge and gave it my best shot. As it turns out, everything went pretty much to plan, perhaps more through luck than judgement, but I did make some mistakes and these I will explain to you throughout this blog.
I now run practical courses on rammed earth, so you can visit the Eco-Shed and have a go before starting out on your own project.
See rammed-earth.org/norfolkcourse for details.
Hang on in there and you will be able to do what I did and build your project for as little as £45 per square metre...