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Straw house building cost?

What would be the average sq/m rate of a straw house compared to the equivilant house built using conventional methods at say $1500 sq/m?

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The design issues are similar to earth buildings, but the need to avoid moisture and weathering is even more crucial. The bales must be dry before installation and remain dry throughout their life, as once wet they are more likely to compost than dry out. The construction detailing and plaster coatings make or break straw bale construction.

Straw bale houses were developed in America and are rising in popularity. However the Earth Building Standards Committee declined to write a straw bale standard at this stage because of the very small number of built examples in New Zealand or Australia to "standardise". If you wanted to build a straw bale house you would need to engage an experienced designer, and do the analysis to apply for a building permit as an "Alternative Solution" under the Building Code.

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Floor plan of house described below

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Project description

"Built to a tight budget, this simple, but well-conceived house in Switzerland accommodates a family of four. In view of the wet subsoil conditions, the structure was raised above the ground on piles. The only section that extends down into the earth is the solid concrete core, which houses sanitary spaces, a kitchen strip, a cloakroom and a cellar. The cellar space is accessible via a trapdoor in the floor. The core element also articulates the elongated house into two parts. These comprise the two children’s rooms at the southern end; and to the north, the living area and parent’s bedroom, with a gallery-level study above this which exploits the additional height afforded by the slope of the roof."

Project details

building type: residential building, residential house
support structure construction: frame construction
facade material: plastic, GRP
topic: GREEN, materials and finishes

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History of strawbale building

As long as human beings have been creating shelter, straw and grasses have been used in conjunction with a variety of building methods to provide safe, dependable, and comfortable housing in many climates and environments.

Walls made from tied bundles of long lengths of straw, stacked in mud mortar, have been constructed for centuries throughout Asia and Europe. Another ancient method, also employed in Asia and Europe, used compacted loose straw coated with a clay slip for walls. Those methods and materials remain in use today, their use declining only where modern construction methods, materials, and codes have become common. In the United States, a new era of building with straw and grasses began in the late 1800s with the development of  stationary horse-powered and the steam-powered balers, which made it possible to compress hay and straw into string or wire-tied rectangular units called bales.

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7 great reasons why you should consider building your next house with Straw Bales:

Reason #1 Energy Efficiency.

A well built straw bale home can save you up to 75% on heating and cooling costs. In fact, in most climates, we do not even install air conditioning units into our homes as the natural cooling cycles of the planet are enough to keep the house cool all summer long.

Reason #2 Sound Proofing.

Straw bale walls provide excellent sound insulation and are superior wall systems for home owners looking to block out the sounds of traffic or airplanes in urban environments.

Reason # 3 Fire resistance.

Straw bale homes have roughly three times the fire resistance of conventional homes. Dense bales mean limited oxygen which in turn means no flames.

Reason # 4 Environmental responsibility.

Building with straw helps the planet in many ways. For example, straw is a waste product that is either burned or composted in standing water. By using the straw instead of eliminating it, we reduce either air pollution or water consumption, both of which impact the environment in general.

Reason #5 Natural Materials

The use of straw as insulation means that the standard insulation materials are removed from the home. Standard fiberglass insulation has formaldehyde in it, a known carcinogen. Bale walls also eliminate the use of plywood in the walls. Plywood contains unhealthy glues that can off-gas into the house over time.

Reason #6 Aesthetics

There is nothing as calming and beautiful as a straw bale wall in a home. Time and time again I walk people through homes and they are immediately struck by the beauty and the “feeling” of the walls. I really can’t explain this one, you’ll just have to walk through your own to see what I mean.

Reason #7 Minimize wood consumption.

If built as a load bearing assembly, the wood in the walls can be completely eliminated, except for around the windows. The harvesting of forests is a global concern and any reduction in the use of wood material is a good thing for the long term health of the planet.

Even infill bale homes can reduce the use of wood by using engineered lumber for the posts and beams. The engineered material uses smaller, faster growing trees in place of larger, slower growing species.

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History
Straw houses have been built on the African plains since the Paleolithic Era. Straw bales were used in construction 400 years ago in Germany; and straw-thatched roofs have long been used in northern Europe and Asia. In the New World, teepees were insulated in winter with loose straw between the inner lining and outer cover. Straw-bale construction was greatly facilitated by the mechanical hay baler, which was invented in the 1850s and was widespread by the 1890s.

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7 Reasons You Should Consider Building A Straw Bale House

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http://www.strawbale.com presents this video on the 7 reasons why you should be building with straw bales. If you want more FREE information on building your own beautiful, energy efficient and cost effective house, sign up for our Free 16 Day Ecourse that covers the entire baling process.

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INSTRUCTIONS: Your group is to research and produce an image and text base brainstorm on the selected alternative building construction method.

Areas of research may include (but not limited to):

History

Design and Construction

Material Use

Environmental Impact

Thermal Mass / Stored Heat Dissipation

Passive Heating and Cooling

Example buildings

Orientation and Site Analysis

Waste

Some resources that may be of use to get you started:

https://en.wikipedia.org/wiki/Rammed_earth

http://www.earthhomes.co.nz/Rammed+Earth+Homes.html

http://www.smarterhomes.org.nz/construction/construction-systems/earth-construction/

https://www.youtube.com/watch?v=H0Ewuj5Bclw

(Please delete this post once your Padlet is complete)

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Advantages of straw bale construction
1. Straw bales are made from a waste product. Once the edible part of the grain has been harvested (such as wheat or rice), the stalks often become a disposal problem for farmers. By bailing the straw, a new life is given to the material. The farmer makes some money by selling the bales and the homebuilder gains an excellent insulation and building material.

2. Homes insulated with straw bale can have insulation values of R-30 to R-35 or more. The thicker the bale, the better the R-value.

3. Straw bale walls are at least eighteen inches thick. This adds aesthetic value to the home as thick wall are expensive to achieve with conventional construction. The thickness of the wall helps to reflect sunlight throughout the room.

4. Due to the thickness of straw bale walls, every window can have a window seat or shelf. This becomes both an aesthetic and practical design element.

5. The concept of straw bale construction is easily understood by even novice builders. With supervision by one knowledgeable straw bale trainer, first-time builders can assist in the construction process. This not only spreads the word about straw bale construction, it also means that the homebuilder can save money by using a volunteer crew to help raise the walls.

6. Straw bales have a low-embodied energy. This means that very little energy was used to manufacture the product as sunlight was the main energy source for growing plant. The only energy needed to make a straw bale is in the bailing process and the transportation to the worksite. Other insulation materials, such as fiberglass, require a substantial amount of energy to produce.

7. Straw bales are 100% biodegradable—when the time comes. Straw Bale homes can last over 100 years if properly maintained. At some point, all structures will eventually be replaced. When the time comes, the straw bales can be plowed back into the earth. Fiberglass, on the other hand, becomes a disposal problem.

8. Straw bale walls can be carved with a knife or chainsaw. Openings around windows or doors can be bullnosed to a nice radius. Bales can also be finished to a sharp angular edge. Nichos can also be carved into the bales.

9. Despite what might seem logical, properly constructed walls made from straw bales have proven to be more flame retardant than conventional wood-frame construction. This is because the bales are dense and tend to just smolder when the ignition source is removed.

10. Straw bale insulation is the most effective in climates where heating and/or cooling of the home is essential for comfort.

11. Straw bale homes can be beautiful as the natural material lends itself to multiple architectural styles.

Disadvantages of Straw Bale Construction
1. SInce it is not a conventional building material, the contractor or do-it-yourselfer will need to learn new construction techniques. Although not difficult, they are different.

2. If straw bale building codes are not part of your local codes, it may be a bit more work to get your plans approved. Contact others in your area and see if they can suggest local architects or engineers that are used to working with natural materials and see they can stamp your plans and help with the approval process.

3. Straw bale walls need to be kept dry as moisture is detrimental to not only straw, but to many building materials. Moisture entering the bales from the roof above is to be avoided at all cost. If the walls of your straw bale home are kept dry, they will last for the life of the building.

4. Areas of extreme humidity and rain my not be appropriate for straw bale construction.

5. Due to the thickness of the walls (usually around 18-20 inches), more of your overall square footage will be unusable due to it being within the wall space.

6. If straw bales are not available within a few hundred miles of your construction site, the cost of shipping them, along with the potential pollution from the transportation, must be taken into account.

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Did you know a standard straw bale (450mm thick) has an R-value in excess of 4.8 and up to 9

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The purpose of the hay is to feed animals. Straw, on the other hand, is simply the stalks of standing plants that contain no grain. The grain is harvested from the plants by a machine that cuts it off of the stalk. The grain is then removed from the field and the stalks are left to die, standing.