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Revision as of 08:04, 28 February 2010
Project Background
CCAT is building a tool shed with green methods in mind so it is called the green shed. Part of this green design is the walls that will be made from as many natural or recycled materials as is reasonable. This project offers students the opportunity to get hands-on experience with various wall infill methods and materials.
The concrete foundation of the green shed was poured to make a standard 6 inch wide wall. This is not wide enough for most earth building methods to be of much insulation value. The foundation for the walls will have to be widened to accommodate.
The frequently wet nature of our climate may present other obstacles. The water soluble nature of many natural materials will be considered in material selection. Some methods using organic matter present the issue of rotting. The tendency of organic matter to rot in out wet climate will require the walls to "breathe" well so as to not trap moisture inside.
An existing example of natural wall construction exists at CCAT http://www.appropedia.org/CCAT_natural_wall_constructionThere is an example of papercrete and of straw and clay-slip. It may yet be used for inspiration on the insulation walls. Cob and cordwood are also being considered.
Project Members
Garrett Duffy and Marqes Mayo
Project Definition
The north wall will be another example and experiment in natural building. Insulation will be one functonal motive but also keeping in mind that this wall is for a tool shed. This wall will be designed to hang tools on in some way. The natural bulding technique known as cordwood fits the demand for insulation and offers future builder the opportunity to mount hooks for tools.
Literature review
Garrett's sources
Books
• Callahan, Tim, and Clarke Snell. Building Green: A Complete How-To Guide to Alternative Building Methods Earth Plaster * Straw Bale * Cordwood * Cob * Living Roofs. New York: Lark Books, 2005. Print.
This book offers a fairly solid overview of the listed building methods. For cordwood it warns against various errors the experts have made, such as using hardwoods and sealing the wood ends.
• Chiras, Daniel D.. The Natural House: A Complete Guide to Healthy, Energy-Efficient, Environmental Homes. White River Junction: Chelsea Green, 2000. Print.
"The natural house" goes into more detail about actual construction and foundation considerations.
• Cordwood Building: The State of the Art (Natural Building Series). Gabriola Island, BC: New Society Publishers, 2003. Print.
This book is by far the most comprehensive book found so far and is exclusively about cordwood construction. It details mortar mixtures, wood types, wall types and some advanced methods.
Journal
• Pierquet, Patrick , Jim Bowyer, and Pat Huelman. "Thermal performance and embodied energy of cold climate wall system." Forest Products Journal 48.6 (1998): 53. ProQuest. Web. 13 Feb. 2010.
The concern of this article is the thermal performance of twelve building methods and their embodied energy. two of them of relevance to this project are 2x4 construction and cordwood for the sake of comparison.
Websites
Stankevitz, Alan. "DayCreek Journal - June 25, 2000." Daycreek Home Page. N.p., n.d. Web. 13 Feb. 2010. <http://daycreek.com/dc/HTML/journal062500.htm>
The above site has a responsive forum for those who have cordwood questions.
"Cordwood." Chaetreuse. N.p., n.d. Web. 13 Feb. 2010. www.brightgreenresearch.org/images/pdf/2009.11.02_MaterialConcept_Cordwood.pdf
This page reports some information about cordwood, such as R values and compressive strength of mortar mixes.
So what is cordwood?
Cordwood is amoung the several common natural building methods. Firewood is often sold in a unit known as a cord. Such woods is at times a sutable bulding material. The more durable softwoods tend to be best. logs at least 12" long are secured in to the wall with a mortar of sorts. The length of the logs are mounted perpendicular to the wall itself. The mortar may be like concrete, cob, or even paper crete. The plan of this project is to use western red cedar logs and mortar made from portland cement, sand, lime and saw dust.
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Criteria
Criteria | Constraints | Weight |
---|---|---|
Maintainability | Repairs expected less than once per year. | 8 |
Long lasting | At least 8 years expected | 7 |
Appropriateness for tool shed | Can accept at least one shelf | 4 |
Tolerance to wet climate | Not expected to mold or rot | 9 |
Ease of getting materials | Most materials acquired in Humboldt bay region | 8 |
Ease of building | Done with unskilled labor | 7 |
Thickness | Less than 12 inches | 10 |
Insulation | R-value comparable to standard construction | 7 |
Durability | Can withstand minor abuse | 8 |
Use of recycled materials | Substantially less embodied energy than standard construction | 9 |
Cost | Less than $300 | 10 |
Consideration: potential for the wall as an education tool in green-building
Materials and Retail Costs
Quantity | Material | total cost |
---|---|---|
(3) 80 lb bags | Portland cement | $39.00 |
0.5 cubic yards | masonry sand | $45.00 |
4.5 cubic feet | sawdust | Free |
(3) bags | Hydrated lime | $45.00 |
1/4 or a cord | western red cedar logs | $80.00 (rough estimate) |
Grand Total | $209 |
potential discounts and donations not included.
Tools to be rented from CCAT
shovels
wheel barrow
chain saw
hand saw
trowels
garden hoe
drawknife
splitting wedge
sledge hammer
axe
measuring tape