Green Building
Adobe
Adobe
is one of the oldest building materials in use. It is basically just
dirt that has been moistened with water, sometimes with chopped straw
or other fibers added for strength, and then allowed to dry in the
desired shape. Commonly adobe is shaped into uniform blocks that can be
stacked like bricks to form walls, but it can also be simply piled up
over time to create a structure. The best adobe soil will have between
15% and 30% clay in it to bind the material together, with the rest
being mostly sand or larger aggregate. Too much clay will shrink and
crack excessively; too little will allow fragmentation. Sometimes adobe
is stabilized with a small amount of cement or asphalt emulsion added
to keep it intact where it will be subject to excessive weather. Adobe
blocks can be formed either by pouring it into molds and allowing it to
dry, or it can pressed into blocks with a hydraulic or leverage press.
Adobe can also be used for floors that have resilience and beauty,
colored with a thin slip of clay and polished with natural oil.
Adobe
buildings that have substantial eaves to protect the walls and
foundations to keep the adobe off the ground will require less
maintenance than if the walls are left unprotected. Some adobe
buildings have been plastered with Portland cement on the outside in an
attempt to protect the adobe, but this practice has led to failures
when moisture finds a way through a crack in the cement and then can't
readily evaporate. When adobe is used as an exterior plaster it is
either stabilized or replastered on a regular basis.
Adobe
is a good thermal mass material, holding heat and cool well. It does
not insulate very well, so walls made of adobe need some means of
providing insulation to maintain comfort in the building. Sometimes
this is accomplished by creating a double wall, with an air space, or
some other insulation in between. Another approach is placing
insulating materials on the outside.
Definition
source: www.greenhomebuilding.com
For
more information on Adobe building visit:
Cob
Cob is a very old method of building with earth and straw or other fibers. It is quite similar to adobe in that the basic mix of clay and sand is the same, but it usually has a higher percentage of long straw fibers mixed in. Instead of creating uniform blocks to build with, cob is normally applied by hand in large gobs (or cobs) which can be tossed from one person to another during the building process. The traditional way of mixing the clay/sand/straw is with the bare feet; for this reason, it is fairly labor intensive. Some of the process can be mechanized by using a backhoe to do the mixing, but that diminishes the organic nature of it. Because of all the straw, cob can be slightly more insulating than adobe, but it still would not make a very comfortable house in a climate of extreme temperatures. The wonderful thing about cob construction is that it can be a wildly freeform, sculptural affair. I've seen some very charming homes made this way. Cob was a common building material in England in the nineteenth century, and many of those buildings are still standing.A variant of cob is what is commonly called "light straw/clay". This is made with the same long fibers of straw which is tossed like spagetti with a sauce of clay slip. The idea is to coat the straw fibers with enough of the clay to get them to stick together, but not so much that it makes a gummy clump. This material is then tamped into a form and left to set up enough to remove the form. Light straw walls could be useful for interior partitions and even exterior walls if it is thick enough. Such walls would be quite a bit more insulating than cob, but they require a timber frame of some sort because the straw itself would not be load bearing.
Definition source: www.greenhomebuilding.com
Cordwood Masonry
Cordwood (a.k.a Stackwood) ConstructionA cost-efficient (can be built mortgage-free) and sustainable building method utilizing log ends (usually 12-24” in length) laid transversely in a mortar matrix consisting of sand, Portland cement, hydrated lime, and soaked sawdust. Cordwood construction takes advantage of a dual layer wall system similar to a double glazed window. The cavity between the inside and outside mortar walls is insulated with a mix of sawdust and a small amount of lime (rodent repellent) that keeps the home cool in the summer and holds in the heat in the winter. Cordwood homes started to peak in the mid 19th century in Wisconsin where farmers realized the cost and insulative benefits of this construction method. Cordwood structures built over 100-150 years ago show their durability by remaining intact and (in many cases) still being lived in throughout the United States and Europe.
-Peter Turkow
For more information about Cordwood building visit:
www.cordwoodmasonry.com
– (established in the late 70’s, Rob & Jak Roy offer
years of expertise and a plethora of workshops)
www.daycreek.com
– (Alan Stankevitz runs the best online forum for cordwood
&
sustainability I have seen to date and is EXTREMELY active on answering
questions, mostly on cordwood construction. See some of the structures
I helped build under ‘Meet The
Masons’ – Peter & Dave Turkow)
Strawbale
Building with bales of straw has become almost mainstream in some parts of the country, especially in the Southwestern United States. Many localities have specific codes for strawbale construction, and some banks are willing to lend on this technique. Straw is a renewable resource that acts as excellent insulation and is fairly easy to build with. Care must be taken to assure that the straw is kept dry, or it will eventually rot. For this reason it is generally best to allow a strawbale wall to remain breathable; any moisture barrier will invite condensation to collect and undermine the structure. Other possible concerns with strawbale walls are infestation of rodents or insects, so the skin on the straw should resist these critters.There are two major categories of building with strawbales: load-bearing and non-load bearing. A post and beam framework that supports the basic structure of the building, with the bales of straw used as infill, is the most common non-load bearing approach. This is also the only way that many building authorities will allow. While there are many load- bearing strawbale buildings that are standing just fine, care must be taken to consider the possible settling of the strawbales as the weight of the roof, etc. compresses them.
Erecting bale walls can go amazingly quickly, and does not take a lot of skill, but then the rest of the creation of the building is similar to any other wood framed house. In fact strawbale houses typically only save about 15% of the wood used in a conventionally framed house. The cost of finishing a strawbale house can often exceed that of standard construction, because of the specialized work that goes into plastering both sides of the walls. The result is often worth it though, because of the superior insulation and wall depth that is achieved. Source - www.greenhomebuilding.com
For more information on Strawbale building visit:
The Last Straw
StrawbaleSystems.com
Rammed Earth
Ramming earth to create walls is at least as old as the Great Wall of China. It is really quite similar to adobe and cob techniques, in that the soil is mostly clay and sand. The difference is that the material is compressed or tamped into place, usually with forms that create very flat vertical surfaces. Modern rammed earth typically utilizes heavy mechanized equipment to move and compress the material . The walls are normally at least a foot thick to give enough bulk to be stable and provide the thermal mass for comfort. It is best to apply insulating material to the outside of the building to keep the interior temperature constant. The interior surface can be finished in a variety of ways, from natural oil to more standard surfaces. Rammed earth houses tend to have a very solid, quiet feeling inside. Definition source: www.greenhomebuilding.comFor more information about Rammed Earth visit:
www.rammedearthhomes.com
Earthships
Earthships are earth-sheltered autonomous buildings made of tires rammed with earth, which are usually arranged in "U" or horseshoe shaped modules. Each tire is rammed full of earth manually using a sledge hammer. Windows on the sunny side admit light and heat. The open end of the "U" shaped structure faces South in the northern hemisphere, and North in the southern hemisphere, so that the house will catch maximum sunlight in the colder months. An Earthship is designed to interface with its environment wherever possible and create its own utilities.Internal, non-load-bearing walls are often made of a "honey comb" of recycled cans separated by concrete. The walls are then usually thickly plastered, using the pull-tabs on the cans as a lath to hold the adobe and stucco. This is known as a tin can wall.
The roof of an Earthship is heavily insulated. Definition source: http://en.wikipedia.org/wiki/Earthships
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Earthbags
Earthbag construction uses earth as the primary structural element, and it helps create curvaceous, sensual architecture while providing structural integrity. Earthbag structures can be monolithic, meaning that an entire structure is built from foundation to walls to roof using the same materials and methods throughout. Corbelled earthbag domes (bags laid horizontally and stair-stepped up to form the dome) foster simplicity and beauty. Earthbag domes designed with arch openings can eliminate 95 percent of the lumber used to build the average stick-frame house. (See the Honey House, Page 61.)Earthbag building utilizes the ancient technique of rammed earth in conjunction with modern woven polypropylene bags as a flexible form. The basic procedure is simple:
• Fill the bags using suitable pre-moistened earth.
• Close, fold and pin the bags to make neat square-cornered rectangles similar to grocery-store brown bags.
• Lay the finished bags in a masonry-style running bond.
• Thoroughly compact with hand tampers after a row has been laid.
• Lay two strands of four-point barbed wire, pushed down with bricks, between every row. This acts as a “Velcro mortar,” cinching the bags in place and providing exceptional tensile strength (resistance to lengthwise stress) while allowing the rows to be stepped, creating domes and other unusual shapes.
• Apply exterior and interior plasters. Definition source: www.motherearthnews.com
For more information on Earthbag building visit:
Earthbag Forum: http://forums.treehugger.com/viewtopic.php?t=46
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Rainwater Catchment Systems
At the moment, 2 types of systems are generally used. These include homebrew systems and commercial systems. Both of these systems are known under the term water harvesters and require only a limited amount of knowledge to set up (if basic systems are used). In both cases, the system consists of a storage tank to store the water and piping (to guide the water in). Additionally, extra pressuring equipment as pressure vessels, inline pump controllers or pressure sensitive pumps may also be required. [3] Finally, water purifying equipment as water-purifying plants, UV-lights or distillation equipment are sometimes (depending on local conditions [4] ) added to purify the collected water. The system is then called a Greywater treatment system. Greywater systems are usually preferred over regular water harvesters as they allow the system to not only treat the rainwater, but water from other sources as well (eg the watercloset; if plants are used). However, this feature may also be averted by using a UV-lamp and composting toilet instead.Depending on local circumstances, a gravity-fed system may already be enough to have a pressured water collection system. [5] In the latter case, no pumps/pressure vessels are thus required to have a pressured system. In practice, gravity-controlled systems are usually created by placing the water harvester on an elevation (eg rooftops).
Definition source: http://en.wikipedia.org/wiki/Rainwater_harvesting
For more information about Rainwater Catchment Systems visit:
http://www.thefarm.org/charities/i4at/surv/raincat.htm
http://www.rain-barrel.net/rainwater-catchment.html
To purchase equipment: http://www.composters.com/rain-barrels.php
To purchase equipment: http://www.rainwatercollection.com/rainwater_collection_quick.html
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