Las Malvinas ecoladrillo schoolroom: Difference between revisions

Revision as of 16:38, 2 July 2012

Problem Definition

Objective

The objective is to construct a classroom that will hold approximately 25 students under the age of 10. The classroom will be constructed using locally sourced materials (when possible) that explore alternative building methods. The classroom will cost no more than conventional construction methods and be at least equally durable.

Background

Las Malvinas is a community near Santo Domingo, the capital city of the Dominican Republic. There are more than 150 families who live in this semi-rural setting, situated next to the Isabella River. By a vote of hands, the community decided that the project they want to collaborate on the most is to add another classroom on to their school using alternative construction methods like papercrete and ecoladrillo.

Papercrete is similar to concrete blocks, but these blocks are made with recycled paper. Ecoladrillo uses wooden frames, plastic bottles, chicken wire, and concrete to make walls.

There is an abundance of both materials (bottles and recycled paper), and there is a need in the community for more space to hold their youngest students. So, we're going to work with the cheapest, most local materials to help Las Malvinas complete this project, while we students from Humboldt State are learning how to implement modes of sustainable construction.

en espanol: Las Malvinas es una comunidad cerca de Santo Domingo, en la República Dominicana. Hay más que 150 familias que se viven en esta escenario rural, al lado del Río Isabella. Por un voto de las manos, la comunidad decidio que el proyecto que se quieren más es que construir una aula para la escuela, usando modos alternativos de construcción como "papercrete" y "ecoladrillo."

"Papercrete" es similar a bloques de concreto, pero estos bloques son de papel reciclado. "Ecoladrillo" se usa botellas plásticas y concreto para hacer paredes.

Hay un abundancia de ambos materiales (botellas y papel reciclados), y necesitan más espacio en la escuela. Entonces, váminos a trabajar con las materiales más locales y baratos para ayudar esta comunidad cumplir este objetivo mientras estámos apriendo a implementar modos de construcción sostenable.

Criteria

Criteria and constrains are needed to determine the success of a solution. Criteria are weighted with 10 being most important and 0 being least important.
Criteria	Constraint	Weight
Safety	The classroom meets or exceeds local building codes	10
Reproduction Costs	The total cost of construction is less than the cost of traditional construction.	8
Appropriate Materials	Building materials are local, alternatively resourced, and may be easily obtained by the community.	7
Aesthetics	The classroom looks good with the existing school structure while having a unique appearance that draws positive attention to its alternative construction.	8
Ease of Use	The classroom comfortably accommodates the most number of students possible for the given space, up to 35 students.	7
Community Interest	Maximize community involvement to develop their interest in the project, as well as their skills and knowledge necessary to replicate the project later.	10
Research and Development Costs	Spend no more than US$1000	5

Literature Review

See /Literature_Review for relevant research completed for this project.

Timeline

Jun. 7, 2012

First group meeting with the community
Multiple projects and alternative materials are presented
Community members takes a vote on which they are most interested in
The decision is made to construct an additional classroom at the school
High interest in using papercrete as a building material

Jun. 9, 2012 - Jun. 10, 2012

Meeting with Revark at the building site to take measurements
Ideas about new room location are discussed
Possibility of building two smaller rooms instead of one large room
Begin soaking paper from the trash for papercrete (later discarded because organic material such as food waste on the paper brought on accelerated decomposition)
Acquire large free source of sawdust from a nearby coffin manufacturer (decision is made to explore sawdust as possible building material)

Jun. 11, 2012

Divid research and material aquisition responsibilities amongst the team

-General construction, structure (Ariel)

-Roofing, liter of light (Amber)

-Natural paints (Shalyn)

-Climate (Luis)

-Ecoladrillo, papercrete (Camille)

-Rammed earth (Jocelyn)

-Alternative infill possibilities with sawdust (Eric)

Begin collecting bottles off the street for ecoladrillo
Begin building ecoladrillo test brick #1 with 2"X4" wood and 2 layers of sand filled bottles
Shalyn is dedicated official scribe due to the need for thorough project notes

Jun. 12, 2012

Meeting with Revark to look over building design
Commit to traditional column and beam style structure with some type of alternative infill
Start search for community members with construction experience who could assist in the building of the columns
Develop criteria set and weight each criterion by importance
Begin visiting hardware stores to scope out materials and prices

Jun. 15, 2012

First meeting with school director to discuss building design and location
Issues with design/location:

-New room would block windows of existing room

-Idea to move windows to north wall is rejected due to importance of opposite facing windows for airflow

-Close proximity to the bathrooms

-Blocked on east and west walls by existing structures, which are the ideal walls for window placement

Decision is made to build a long, narrow, rectangle shaped room in the available area on the north wall of the school
Possibility of constructing additional recycling structure in the front of the school

Jun. 16, 2012

Begin constructing "labyrinth" of ecoladrillo
Three more test blocks are constructed

-Test block #2: 1 square meter 1"X3" wood frame, one layer of empty bottles (size/shape not taken into consideration), open spaces stuffed with plastic trash.

-Test block #3: 1 square meter 1"X3" wood frame, one layer of empty Dasani water bottles (bottom row full of sand for stability and increased thermal mass), 4 rows of 13 bottles, open spaces stuffed with plastic trash

-Test block #4: 1 square meter 1"X2" wood frame, one layer of empty similar shaped bottles, less need for trash stuffing due to thinner wood

Start experimenting with sawdust plasters on test blocks (discredited because the test plasters were covered up by a community member due to miscommunication
General test notes: Sand filled bottles are too heavy and time consuming to make, 1"X2" wood requires less trash stuffing but is too weak, over-packing makes plaster application more difficult
Finalize literature review and problem definition

Jun. 17, 2012

Structure

Take measurements for columns and excavated for foundations
Decide to build walls on top of existing short perimeter walls to maximize room space
Begin cutting, bending, and tying rebar into appropriate forms for the columns
Pour concrete foundations and secure rebar column forms
Build wooden moulds and pour concrete for column bases

Infill

Further testing of sawdust plasters for ecoladrillo:

-Ratio #1: 3 sawdust, 2 sand, 1 cement, 0 lime

-Ratio #2: 3 sawdust, 3 sand, 2 cement, 0 lime

-Ratio #3: Equal parts sawdust, sand, and cement, 0 lime

-Ratio #4: 1 sawdust, 1 sand, 1 cement, 1/2 lime

General test notes: ratio #1 is very chunky and poorly mixed, ratio #2 is clearly smoother and stronger within the first hour after application (strong possibility), ratio #3 and #4 are very similar to ratio #2 (decision is made to experiment with ratios close to ratio #2)
More bottle collection off the street for ecoladrillo (decision is made to explore other bottle collection methods because street collection is too inefficient)

Jun. 18, 2012

Group meeting to break into teams and develop team objectives for the following day:

-Team structure (Camille and Jocelyn) objectives: Re-plum rebar to prep for column pouring, pour concrete for the full height of the 4 columns, remove razor wire and poles from chain link fence

-Team ecoladrillo (Eric and Ariel) objectives: Review previous plaster ratios and continue testing new plaster ratios, gather more sawdust from coffin manufacturer

-Team papercrete (Shalyn and Amber) objectives: Find large source of clean free paper and begin soaking paper with lime

Jun. 19, 2012

Structure

Remove fence and razor wire surrounding the building site to make room for wooden column moulds
Aquire more scrap wood from community members for wooden moulds
Decide to use existing fence posts to bolster strength of columns
Decide to drill holes in column moulds for protruding steel wire ties secured to rebar within the column

-Steel wire will be used to tie walls into columns

Begin cutting, bending, and tying rebar forms for concrete beams
Decide to build 1 beam on top of each perimeter wall instead of 2 (one on top and one in the middle) due to the added strength of the preexisting foundation for the low perimeter wall
Build moulds and pour concrete for 2 of the 4 columns

Infill

Begin mixing and testing papercrete:

-Test mix #1: 8 soaked and blended newspaper, 4 cement, 2 sand, 1 soaked lime

-Test mix #2: 8 soaked and blended office paper, 4 cement, 2 sand, 1 soaked lime

General test notes: Newspaper is much easier to re-pulp than office paper, both tests are insufficiently mixed resulting in strength and aesthetic inconsistencies, over blending of the paper results in minimized tensile strength and under blending of the paper results in greater mix inconsistency, water used in paper blending and lime soaking is sufficient to add and mix in sand and cement (no need to add extra water), both mixes are left to dry in 5 gallon buckets (for lack of proper moulds) and their removal is incredibly difficult (not recommended)
Further sawdust plaster tests for ecoladrillo:

-Ratio #5: 4 sawdust, 3 sand, 2 cement, 1/4 lime

General test notes: Sawdust and lime are soaked with water before being added to the mix, ratio is mixed on the ground with shovels instead of in a bucket by hand (achieve much more consistent mix), ratio #5 is similar in strength and smoothness to ratio #2 despite increased sawdust and decreased cement (decision is made to attempt ratio #1 again with new soaking and mixing technique)

Jun. 21, 2012

Structure

Chisel the 2 previously pour columns to the right height (poured too high)
Build moulds and pour concrete for the final 2 columns

Infill

Further testing of papercrete:

-Test mix #3: 9 soaked and blended newspaper, 3 soaked and blended office paper, 6 cement, 2 sand, 1 soaked lime

General test notes: Test mix #3 is very heavy (too much cement and moisture retention from the paper), decision is made to experiment with less paper and cement and more sand
Further testing of sawdust plasters:

-Ratio #6 (back to basics): 3 sawdust, 2 sand, 1 cement, 1/4 lime

General test notes: Ratio #6 is the same as ratio #1 but with an addition of lime, new mixing and soaking technique results in much smoother and more consistent mix, higher sawdust content results in much longer drying time (5+ days with afternoon sun exposure and minimal rain)

Jun. 22, 2012

Acquire large source of donated newspaper from El Nuevo Diario, a local news provider (10 bales)
Begin shredding and soaking paper for new papercrete tests

Jun. 23, 2012

(add tv crew info)

Structure

Dig and pour foundation for the south west corner between the perimeter wall and the school
Cut the extra rebar off the tops of the columns
Cut, bend, and tie all of the rebar forms for the beams
Chisel into the north wall of the school where cross beams could be tied in
Determine that the clay content in surrounding earth is high enough to attempt testing rammed earth

Infill

Secure free usage of a local industry's block making machine to make legitimate papercrete blocks (first available time slot is early the following morning)
Blend paper to prepare for block making

Jun. 24, 2012

Structure

Build supports and place rebar forms for the beams
Tie and weld rebar from the columns to the beams, and from the cross beams to the school
Build moulds and pour concrete for all 6 beams/crossbeams
Drill holes in beamn moulds for protruding steel wire ties secured to rebar within the column

-Steel ties will be used to tie the wall into the beam

Infill

Use of the block factory for papercrete is pushed back one day due to insufficient quantity of mix (need 10 gallons of mix to press 4 blocks)

Jun. 25, 2012

Infill

press first four papercrete test blocks at block factory with new ratio (test mix #4: 4 paper, 2 sand, 1 cement)
General test notes: First mix is too wet to use (second mix has to made with hand pressed paper), factory workers add a large amount of sand and some cement (quantities indeterminable) to the mix to improve the consistency, blocks break later due to excessive handling while still drying
Decision is made to sun dry paper before mixing as well as to increase the ratio of sand and cement to paper

Jun. 26, 2012

Structure

Acquire wooden beams for the roof
Meeting with school director to revise Revark's letter asking for a roof donation
Remove moulds from finished beams

Infill

Press second four papercrete test blocks at the block factory with adjusted ratio (test mix #5: 2 paper, 2 sand, 1 cement)
General test notes: Unsifted sand is used without any apparent disadvantages, sun dried paper and adjusted ratio work much better, use of block press reduces drying time from 5+ days to about three
Decision is made to use test mix #5 with sun dried paper and unsifted sand in final block making
Prepare 100+ gallons of papercrete mix for a full day of block making scheduled on Jun. 28
Sort bottles for ecoladrillo
Frame west wall for ecoladrillo

Jun. 27, 2012

Fill and secure bottom two quadrants of west wall with bottles and chicken wire for ecoladrillo
Frame long north wall for ecoladrillo (south wall is kept unframed for ease of access to back work area, east wall is left unframed in hopes of using papercrete)

Jun. 28, 2012

Structure

Construct wooden rafter for zinc roof (slopped to the west, with the north west end 2 inches higher than than southwest end for ease of potential rainwater catchment installation)
Community members express concern with rainwater flowing off new roof onto where they park their cars (increased motivation to install catchment
Representative from INCA comes out to building site (strong possibility of roof donation)

Infill

Block press at the factory breaks, putting papercrete on indefinite stand-by
Fill and secure west wall and 2/3 of north wall with ecoladrillo (1,231 bottles used, about 115 bottles for every 8ft squared)
Final 1/3 cannot be filled before backside is plastered (because backside inaccessibilty requires it to be plastered from the inside

Jun. 29, 2012

Take day off from site to collect bottles for final few quadrants of ecoladrillo

Jun. 30, 2012

Structure

Stack and mortar concrete blocks for east wall and south wall door frames
Tie block columns into beams
Acquire large source of free broken tiles for flooring

Infill

Begin mixing and plastering interior ecoladrillo walls with sawdust plaster (ratio #5)
Cut in edges where wall and column/beam meet with traditional cement plaster
Plaster the backside of half of the inaccessible wall and fill and secure with ecoladrillo

Jul. 1, 2012

Celebrate Jocelyn's birthday onsite with a mid-day singing, dancing, and icecream break

Structure

Begin first broken tile floor test

-Test mortar #1: 1/2 inch layer of sand, 3 inch layer of mix (4 sand, 1 cement), tile layer with mortar (4 sand, 1 cement)

-Test mortar #2: 1/2 inch layer of sand, 3 inch layer of mix (4 sand, 1 cement), tile layer with mortar (2 sand, 1 cement)

Infill

Frame south and west walls for ecoladrillo
Begin plastering exterior walls with sawdust plaster
Finish plastering backside of inaccessible wall
Finish filling and securing north wall with ecoladrillo
Begin applying second layer of sawdust plaster over interior walls

References

@@ Line 59: / Line 59: @@
 ==Literature Review==
-===Climate===
-The Dominican Republic is in a tropical climate zone, where rainfall varies seasonally but temperatures are relatively static, <ref>(2012). "Central America and the Caribbean: Dominican Republic." <https://www.cia.gov/library/publications/the-world-factbook/geos/dr.html> (Jun. 16, 2012).
-</ref> ranging from 64 to 90 degrees Fahrenheit year round.<ref name=Peacecorps>
-"Insights from the field: Appendix B." <http://www.peacecorps.gov/wws/publications/insights/pdf/InsightsBackground.pdf> (jun. 16, 2012)
-</ref> The rainy season begins in early summer and lasts through mid fall, with the the most powerful tropical storms occurring during August and September.<ref name=Peacecorps /> The average annual rainfall is 150cm<ref> Elliot, D., Shwartz, M., George, R., Haymes, S., Heilmiller, D., Scott, G. (2001). ''Wind Energy Resource Atlas of the Dominican Republic'', Natural Renewable Energy Laboratory.
-</ref>, much of which falls on the northern side of the island. This results in cooler temperatures and higher humidity in comparison to the south.<ref>
-(2012). "PCDR facts." <http://dominican.peacecorps.gov/pcdr.php> (Jun. 16, 2012).
-</ref>
-===Earthen Flooring===
+See [http://www.appropedia.org/Las_Malvinas_Alternative_Construction_2012/Literature_Review /Literature_Review] for relevant research completed for this project.
-====Introduction====
-An earthen floor is made up of four basic layers. A layer of substrate dirt or sawdust that is laid down on top of a layer of fine gravel, which is then covered with a layer of clay or sand and sealed with a layer of hemp or linseed oil. The result is a porous, supple and durable floor which can be made for less than a dollar per square foot. (including labor).<ref>Timbers, Amelia (2008). "Green Flooring Down to Earth." <http://www.matternetwork.com/2008/5/green-flooring-down-to-earth.cfm> (Jun. 16, 2012).</ref>Rammed earth is a style of earthen floor that uses tamping or ramming to compact and harden the layers. Specific ingredients and construction methods vary by location. The overarching idea is to add water and stabilizing agents like sand and straw to dirt, which is then compacted until hard. Once dry, seal it with an oxidizing oil like linseed or hemp oil. <ref>Team Planet Green, (2009). "Rammed Earth Flooring Guide." <http://planetgreen.discovery.com/feature/green-materials-guide/flooring-rammed-earth.html> (Jun. 16, 2012).</ref>
-====Methods====
-For a general rammed earth floor, the first step is to lay down a plastic moisture barrier sandwiched between two thin layers of sand, followed by 4 to 6 inches of compacted "road base mixture."
-*clay, sand, and various types of gravel (ratio unimportant)
-It is important to tamp the floor and sprinkle it with water every additional few inches to ensure good and even compaction. The next step is to add a one inch layer of standard earth plaster mix.
-*6 parts sand, 2 parts clay, 1 part finely chopped straw
-The plaster should then be troweled smooth and allowed to dry. Once dry, the final step is to lay down four layers of linseed or hemp oil, allowing each layer to dry before applying the next. The last three coats of oil should be mixed with increasing ratios of citrus paint thinner. <ref> Sirna, Tony (2012). "How To Pour A Rammed Earth Floor/Adobe Floor." <http://www.dancingrabbit.org/about-dancing-rabbit-ecovillage/eco-living/building/natural-building/earthen-floor/> (Jun. 16, 2012).</ref>
-To get the right mix, experiment with a test area of at least 3x3 ft. The mix should be strong enough that it is not powdery when it dries, and it must contain enough fiber so that there are no cracks. Apply the mixture with a trowel in 1/2-3/4" layer. The material should come off cleanly and easily as you move the trowel across the sub-floor. If it sticks, there’s either too much clay or not enough moisture; if it won’t stick to the trowel, there’s either too much moisture or not enough clay. <ref name=Homeandgarden>Tobias, Lori (2003). "Feet on the Ground: Earth Floors." <http://www.naturalhomeandgarden.com/article.aspx?id=2064> (Jun. 16, 2012).</ref>
-Homeowners in a wet climate should put down several inches of gravel to enhance drainage. This can be a three- to four- inch layer of clay, sand, and gravel or crushed stone, on top of which lays the half-inch layer of finer mix. If you pour this supportive layer in a damp state—and even add lime to the mixture—it will dry and harden more quickly. <ref name=Homeandgarden />
-A typical earthen floor might include a 2.5-inch base layer of 70% sand, 30% clay, with handfuls of long straw for tensile strength. Once it is dry, the final layer will be installed and smoothed with a trowel, composed of a similar sand to clay ratio, but mixed with very short chopped straw. <ref>Ziggy, (2008). "Natural Building 101: How To Build an Earthen or Adobe Floor." <http://greenbuildingelements.com/2008/11/06/natural-building-101-how-to-make-an-earthen-or-adobe-floor/> (Jun. 16, 2012). </ref>
-====Linseed Oil Coating====
-Increasing amounts of paint thinner in the linseed coatings allow deep penetration of the oil into the floor:
-:1st coat - Only linseed oil
-:2nd coat - 3:1 linseed to paint thinner
-:3rd coat - 2:2
-:4th coat - 1:3
-Boiled linseed oil contains solvents and is highly toxic, while eco-friendly linseed oil can be expensive. “As a compromise, we take raw linseed oil and put it in the sun in shallow pans covered with a piece of glass, leaving a tiny air space. The oil pre-oxidizes and dries faster. It’s called sun-thickened oil.” <ref name=Homeandgarden />
-====Stabilizers====
-The main categories of binders used for earth construction are Portland cement, lime, bitumen, natural fibre and chemical solutions such as silicates. Benefits of cement addition is improved structural integrity, while a downside is reduced permeability of earthen mixture and thus natural ability of earth to allow passage of moisture throughout the soil mass is reduced. <ref name=People>Maniatidis, V., Walker, P. (2003). ''A Review of Rammed Earth Construction'', Natural Building Technology Group.</ref>
-Tests have indicated that there is an optimum lime dosage for a soil beyond which compressive strength decreases. The likely dosages are between 6-12% lime by dry weight and will increase as clay content increases. <ref name=People />
-===Alternative Infill===
-====Introduction====
-Infill is used in conjunction with frame or post-and-beam style structures to fill in the wall spaces. In such styles, a wood frame or concrete column and beam structure is used to hold up the roof and provide structural support, while the infill is used to seal the building from the elements, as well as provide thermal mass and insulation. Infill is  usually considered non-structural, however it can increase lateral support depending on the type. <ref>Dorji, J., Thambiratnam, D.P. (2009). "Modelling and Analysis of Infilled Frame Structures Under Seismic Loads." ''The Open Construction and Building Technology Journal'', 3, 119-126.</ref>
-====Ecoladrillo====
-“Eco-bricks” are a method of alternative infill that use plastic bottles and trash in the bulk of their composition. Bottles and trash are stacked and compacted into a wood frame and held secure by a layer of chicken wire on each face. The two faces are then plastered smooth.<ref>"Creating Green Communities." <http://www.mariposadrfoundation.org/Creating_Green_Communities.html> (Jun. 16, 2012).</ref> Any inorganic waste material can be used to fill the bricks, however ideal materials are those that cannot be recycled others. Examples include: food packaging, old socks, razor blades, used up pens and markers, clothing tags, cotton swabs, etc. The process of "up-cycling" such materials that would otherwise end up in the trash reduces waste and significantly cuts construction costs. <ref>(2011). "Making eco-bricks." <http://bottleschools.org/wiki/Making_%E2%80%9Ceco-bricks%E2%80%9D> (Jun. 16, 2012).</ref>
-That being said, not all trash makes for good infill material. Anything organic such as food waste will not work. Trash must be clean and moisture free, as well as the bottles, and it is best to stay away from paper waste if at all possible. It is also important to stuff bottles as full as possible to increase insulation. Training of community members about these material requirements is important to ensure a stable and safe structure.<ref> Kutner, Laura (2012). “Trash for Peace: Engaging Children, Youth and Community for a World without Waste.” ''Children, Youth and Environments'', 22(1), 294-303.</ref>
-====Papercrete====
-Papercrete is a method of building traditional style cinder blocks out of paper. Soaked and shredded paper is mixed with sand and a binder such as Portland cement or clay, and then compressed into a block mould. Papercrete blocks can be stacked and mortared with papercrete mortar and used as a substitute for traditional concrete blocks.  <ref name=greenhome>Hart, Kelly. "Papercrete." <http://www.greenhomebuilding.com/papercrete.htm> (Jun. 23, 2012). </ref>
-The type and quality of paper can vary depending on availability. Newsprint or office paper is ideal, but any grade of paper that can be re-pulped will work. Paper that is waterproof and/or has a wax or plastic component such as butcher paper, cardboard, and juice cartons cannot be easily separated in water and will not work. <ref>Fuller, Barry (2012). "Introduction to Papercrete." <http://www.livinginpaper.com> (Jun. 23, 2012). </ref>
-The ratio of sand is dependent on the needs of the papercrete. A mix with more sand and less paper will dry faster, shrink less, and have more thermal mass and compaction strength. A mixture with more paper and less sand will be provide more insulation and will have more tensile strength, reducing the need for re-bar or other types of tensile supports. If your source of paper is free, more paper will also reduce material costs.<ref>Mohammad, B. (2009). "Papercrete as Infill Materials for Composite Wall System." ''European Journal on Scientific Research'', 34(4), 455-462.</ref>
-Disadvantages to papercrete  in comparison to traditional concrete include:
-*Longer drying time, especially in humid climates
-*More vulnerability to fire
-*More vulnerability to mold growth
-*More vulnerability to water damage
-Advantaves to papercrete include:
-*More dimensional stability under different types of stresses
-*Significantly lighter than traditional block
-*High insulation (R-value of 2 per every half inch)
-*Resistant against rodent and insect infestation<ref name=greenhome />
-====Sawdust====
-When considering sawdust as a building material, there are functionally two different types wood: hardwood and softwood. The quality of the sawdust will vary depending on the species, but most hardwoods are relatively better than softwoods at absorbing water, which are typically harder and grainier. For this reason, sawdust gathered from hardwoods is more ideal. Sawdust can be used in mixes with clay to make adobe and cob or with cement to make concrete and plaster substitutes. It can provide insulation, protection against freezing. It can also be found for free.<ref name=Countryside>Taylor, Charmaine (1998). "Building for free with alternative natural materials." <http://www.countrysidemag.com/issues/85/85-3/Charmaine_R_Taylor.html> (Jun. 16, 2012).</ref>
-Cob and adobe are made from mixtures of clay, sand, lime, sawdust and/or green waste. The ratio's can vary greatly depending on availability and quality of materials, making cob and adobe very adaptable building materials. Because Las Malvinas has an abundance of sawdust, the ratio with the most potential requires 9 parts sawdust, 3 parts clay, 2 parts lime, and 1 part sand. The sawdust is soaked overnight and dried for a few hours, then mixed by hand or by hoe with the rest of the mixture and water.<ref name=Countryside /> The amount of water need varies depending on the moisture content already present in the clay. The mixture can be made into adobe bricks or built up in monolith. Cob or adobe made with more sawdust rather than green waste will also dry faster.<ref> "Making Cob." <http://www.pequals.com/at/natoven/making_cob.htm> (Jun. 16, 2012) </ref>
-A mixture of sawdust, sand, and cement can also be used in infill. The mixture requires less cement than concrete or traditional cement plasters, however there is little information regarding its structural integrity. The common ratio is 3 parts sawdust, 2 parts sand, and 1 part cement, and the final mixture can be used as a plaster over another alternative infill material such as eco-brick.<ref>
-Andrews, Russell. "Sawdust, Sand and Cement." <http://www.rainforestinfo.org.au/good_wood/sawment.htm> (Jun. 16, 2012).</ref>
-===Structure===
-====Introduction====
-The structure of a building is there to provide support and stability against the compressive and tensile forces acting on it, both from the dead weight of the building itself and from external stresses such as wind, rain, and earthquakes. There are multiple methods of structural construction, but all of them must meet the same three basic criteria:
-*Structural members must be strong enough
-*Structural members must be joined properly
-*Final Structure must be rigid
-The degree to which each criteria must be met depends on the needs present, the resources available, and the expected forces. <ref>Roy, R. (2004). ''A Guide to Contemporary Post and Beam Construction'', 2nd Ed., New Society Publishers, Gabriola Island.</ref>
-====Post-and-Beam Construction====
-Post-and-beam style construction is a widely used and trusted method of structural building. In this style, concrete columns or wood posts are spaced up to eight feet apart and used as compressive members. The diameter and spacing of the columns/posts are dependent on each other.
-*Larger spacing requires larger diameter columns/posts
-*Smaller columns/posts requires smaller spacing
-These compressive members are hammered into the ground or supported by concrete foundations, the depth of which are dependent on the height of the columns/posts. A general rule for single story structures requires 3 feet of depth for 8 feet of height.<ref name=AWC>(2001). ''Details for Conventional Wood Frame Construction'', American Forest & Paper Association. </ref>
-====Corrugated Tin Roofing====
-Corrugated tin roofing is commonly used in tropical areas because of its durability, sturdiness, and light weight design. The key attribute leading to the ability to remain useful for so long is due to the special corrugated shape the metal is formed to. <ref>(2011). "What is Corrugated Metal Roofing?" <http://www.corrugatedmetalroofing.net/whatis.html> (Jun. 16, 2012).</ref>
-Main types of metals used are aluminum, galvanized steel, copper, aluzinc, and tin. <ref>(2012). "Insulated Corrugated Roof Construction." <http://www.appropedia.org/Insulated_corrugated_roof_construction> (Jun. 16, 2012). </ref>
-Integrated ventilation is very important since this style of material if often used in tropical, humid climates. It is meant to provide insulation from heat during most of the year, so to "provide generous wall openings, large doors and windows" is key during the construction of the roof. <ref>Bradley, Bill (2012). "Low Cost Building in the Tropics - Tropical Building." <http://www.builderbill-diy-help.com/tropical-building.html> (Jun. 16, 2012). </ref>
-===Natural Paints===
-====Introduction====
-Natural paints are non toxic naturally derived alternatives to traditional synthetic household paints.<ref name=bot>Morgan, C., Stevenson, F. (2005). ''Design and Detailing for Deconstruction'', 1st Ed., Scottish Executive, Scotland.</ref> Their non toxicity reduces exposure to harmful air pollutants such as volatile organic compounds (VOCs) that off gas from traditional synthetic paints<ref>(2012). "An Introduction to Indoor Air Quality." ''EPA'', <http://www.epa.gov/iaq/voc.html> (Jun. 23, 2012).</ref>, and many natural paints are biodegradable and compostable.<ref name=bot /> There are many different compositions of natural paints and examples of success for each, however there is little legitimate resistance and durability performance data on any of them. Therefore it is important to test each composition thoroughly before application.<ref>Snavely, M.j. (2007). ''Responsible Purchasing Guide: Paint'', Responsible Purchasing Network. </ref>
-====Ingredients====
-In synthetic paints as well as natural paints, there are four basic ingredients:
-*Pigments
-*Binders
-*Fillers (for bulk and/or texture)
-*Solvents (such as thinners, biocides, and drying catalysts)<ref name=Motherearth>Steen, B., (2006). “Make Safe, Natural Paint.” Mother Earth News (218), http://www.motherearthnews.com/DIY/2006-10-01/Make_Safe_Natural_Paint.aspx </ref>
-Natural alternatives to solvents are generally not as proficient as those used in synthetic paints. Therefore natural paints often take longer to dry and are typically not as smooth or durable against degradation as synthetic paints. This is not universally true and different compositions will have different strengths and weaknesses as well as different aesthetics. <ref>Abdalla, M., (2005). “Natural house paints…good enough to eat.” Ecologist Online, <http://www.theecologist.org/archive_detail.asp?content_id=562> (Jun. 23, 2012).</ref>
-====Preparation and Tools====
-Because there is so little data on natural paints, time and resources for testing are important. Consistency and shade is important and difficult to replicate over multiple mixes, therefore it is crucial to work out the exact quantity of paint needed for the planned area. This requires knowing the absorbency of the surface being painted, the thickness of the paint, and the number of coats needed. Keeping a detailed record of the testing process is highly recommended.<ref name=Innes>Innes, J. (1997). ''Around the House Paint Recipes'', Bulfinch P, Boston.</ref>
-The most important tool to acquire is a good brush. Something with a densely packed head and long stiff bristles works well for mixing paints and breaking up dry ingredients. Alternative application devices such as sponges and rollers are also important to have. They allow for more experimentation with the aesthetics, and different application techniques will work better for different natural paints.<ref name=Innes />
-====Compositions====
-=====Egg Tempera=====
-Egg tempera is composed of raw egg and boiled linseed oil. Any natural pigment can be used to achieve the desired color, and unlike most natural paints, egg tempura paint dries in about an hour. It has a glossy finish, can be used indoors or outdoors, and can last for over 20 years.<ref>Dadd, D.L. (1997). ''Home Safe Home'', The Raadvad Centre, New York. </ref>
-=====Casein Paint=====
-Casein paint is composed of nonfat milk, lime, and some type of filler and pigment. The mixture can be applied indoors or outdoors to all types of surfaces (wood, stone, drywall, wallpaper, earthen plaster, masonry, previously painted surfaces, etc). Casein Paint is also fungi resistant, compostable, and long lasting.<ref name=Motherearth />
-=====Water Based Paints=====
-Water is the the most commonly used natural alternative to synthetic solvents. Distemper is a water based paint composed of chalk and rabbit skin glue. The mixture works best with pastel pigments and its thick texture presents unique aesthetic opportunities. Limewash is a water based paint composed of lime putty and pigment. It is thick and chalky like distemper but with increased durability and antibacterial properties. <ref name=Innes />
 ==Timeline==