CCAT natural wall construction
 Project Requirements
The goal is to construct a test wall that both suits the wet climate of Humboldt County, California and is useful to CCAT.
The Criteria for this project (and other projects of this scale) could look like this:
- Durability (How long are the materials specified to last?)
- Construction Time (What climate and material conditions limit time?)
- Complexity (Can construction be completed by the layperson?)
- Cost (How much will you spend?)
- Locality of Materials (How far will you go to find materials?)
These are basic criteria used to judge the design of this project. When each criterion is examined you can rank them according to importance. For this project, locality of materials, complexity, and construction time were very important factors because this project is one, part of an Appropriate Technology class, two, being constructed by students of HSU, and three, has to be completed in 15 short weeks. Ranking your criteria can be a powerful tool to assist in the timely and orderly design and construction of projects large and small.
 OverviewThe foundation of this wall will be compacted soil with added gravel which will serve as the base for a 1ft tall layer of recycled brick layed in an interlocking pattern will sand mortar. This brick footing serves to keep natural plasters and infill material from coming in direct contact with the ground. The use of sand as mortar also allows the brick foundation to act as a wicking barrier helping to relive the wall of built up moisture through the seasons.
- 8 ft long, 4ft tall, 16in wide in a gentle S curve shape
- Roof dimensions, 9ft long 5.5ft high at peak, with 18in pitches on each side from peak
- Timber frame made from reclaimed timber and driftwood logs, simple 4x4s could work fine
- Recycled brick footing 1ft tall, 1ft wide, mortared with riversand
- One 4 by 4ft section in-filled with papercrete bricks mortared together with papercrete slurry
- One 4 by 4ft section stick framed with wood lath to hold infill of clay-slip-straw
- To be covered by earth/lime plasters by another student in ENGR 305 class
|Qty||Material Needed||Source||Cost||Total Cost|
|~60||Thin Wood Lath||Salvage from local lumber mill||$0||$0|
|3 94lb bags||Portland Cement||Do-it-yourself-Hardware||$12||$36|
|lots||Paper||Shredded office pack from HSU Student Services Building||$0||$0|
|1||Straw Bales||Local seller||~$6||~$8|
|3 Flats||Cedar Shingle||Salvaged and Donated by Pierson Building Center||~$0||~$0|
|~300||Nails for Shingles||CCAT Shed||$0||$0|
|~150||Recycled Bricks||CCAT Recycled Brick Pile||$0||$0|
|2||Natural Log Posts||Beach Salvage||$0||$0|
|~12 ft||4x4 Lumber||CCAT Lumber Rack||$0||$0|
|~20 sqft||Plywood||CCAT Lumber Rack||$0||$0|
 TestingThe first phase of the project after designing is to test CCAT's soil type and paper-crete mixtures. soil shake test seen to the left proved that CCAT has the perfect clay for doing natural construction and will work well for our purposes of clay-slip-straw.
Next to test is the paper-crete mixture. The first test brick was made with a 1:2:1 ratio of paper to cement to water. This made a very soupy mixture that took weeks to dry, but, when it did it was as hard as concrete. After about 6 test mixtures the final ratio that seemed suitable was 3:2:3:1 of paper:Cement:Water:Sand. The use of less water and additive of sand made the bricks shrink less during drying and dry faster. The sand also increases thermal mass and helps with fire resistance. The resulting bricks (shown drying in a window to the right) dried solid like a very hard paper-mache and were also a lot lighter in weight than there would be concrete counterparts. The proportions that I used were what seemed appropriate for the Arcata area. More standard and researched recipes for paper-crete can be found from the Links and References at the bottom of this page or at Paper-crete Block Starter.
 Purposed Timeline
|ITEM||PROPOSED DATE||DATE MET?|
|-Design and site measurements complete||3/4/09||Yes|
|-Dig foundation and set posts||3/23/09||Yes|
|-Construct Roof frame and lay gravel foundation||3/24/09||Yes|
|-Make test paper-crete bricks and forms||3/24/09||Yes|
|-Lay Brick with sand mortar||3/25/09||Yes|
|-Finish roof with cedar shingles||3/28/09||Yes|
|-Nail up wood lath||3/29/09||Yes|
|-Finish making bricks||4/2/09||two weeks late due to rain!|
|-Make large batch of paper-crete for work day||3/14/09||yep|
|-Class work day on wall||4/15/09||Yes!!!|
|-Touch-ups and finishing touches to prepare for plaster||5/1/09||Yes|
 Project in Construction
The gallery below contains pictures from the April 15 class work day. The pictures below describe the process involved with making paper-crete and clay-slip-straw.
 Conclusions and Reflection
Because of relatively good planning and readiness of materials this project was quite feasible and enjoyable. Were it not for the collective help of volunteers and the ENGR 305 class this project may have never been finished. Having now finished there are some things i would do differently in the future.
- I would not have made bricks from the papercrete. The bricks all of slightly different size and shape and with different levels of moisture in them were not ideally suited for building a wall. Using larger forms that contain larger wall sections with tensile reinforcement like bamboo or scrap metal would have been a lot easier and required a lot less paper.
- Just a note, paper-crete takes forever to dry in a coastal climate, especially if there is not enough cement in the mixture and too much water. Some applications I have researched suggest straining the paper-crete through a wire mesh to relieve it of a portion of its water helps it to dry a lot faster.
- I would have liked to have experimented more with different types of paper in the mixtures I made. The shredded paper was so readily available it was all that I used. Word of mouth and research suggests that using different types of paper (e.g. newspaper, magazines) produces a significantly different consistency of paper-crete. So I would suggest experimenting to see which type is most appropriate to your project.
- Even if your project is small, get others involved! The process of natural building can be fun and educational and most of all it brings people together with one goal in mind, to build something maybe new and exciting that is a hands on alternative to conventional building practices.
 Links to Relevant Sites
- ArchitectureWeek-Building with Paper-crete
- Paper-crete Resource Webpage
- Wikipedia on paper-crete
- Oikos Building Green Source
 References (Annotated)
- • Callahan, Tim, and Clarke Snell. Building Green: A Complete How-To Guide to Alternative Building Methods Earth Plaster * Straw Bale * Cord wood * Cob * Living Roofs. New York: Lark Books, 2005.
In this very complete 600 plus pages guidebook, Callahan and Snell demonstrate alternative building methods of cob, straw bale, earth plaster, cord wood and living roofs. The book is filled with history, applications, methods, and afterthoughts from the authors’ firsthand experience with building all of the above listed alternative building methods. The book also provides step by step building processes with notes on basic construction of foundations, walls, doorframes, drainage trenches, trussing, and site preparation. Contains over 150 pages on proper calculations for soil, r-value, shrinkage, stick frame construction, and environmental specs. Thoroughly covers natural wall construction and earthen plasters in a manner that an amateur could understand.
- • Norton, John. Building with Earth: A Handbook. London: Practical Action, 1997.
This handbook has practical applications for choosing whether or not earthen construction is appropriate or suitable for your site as well as an overview of how to build with earth. Contains a synopsis of the logistics for site appropriateness, soil testing, earthquake considerations, costs, resource use. Continues on to explain wall construction using the methods of wattle and daub, direct moulding, adobe, mud brick, rammed earth, and compressed blocks. The handbook continues to describe the same tone roofs, foundations and floors, and weather protection. Most of the experience the author has comes from earthen construction in Africa and China. This handbook has good overview of earth building, but lacks the attention to detail that a novice earth builder would need to begin construction.
- • How to build walks, walls & patio floors, (A Sunset book, 170). Menlo Park, CA: Lane Books, 1973.
This book is a rather contemporary overview of building walls, walks, and patio floors. It explains wall building foundations and materials for use that include brick, stone, adobe bricks, and concrete cast. This book does explain to good depth the different types of patio and walk construction. It includes loose aggregate, concrete with many alterations to it including pebble mosaics, brick, adobe brick, tile, flagstone, and asphalt. Goes over most contemporary or western brick styles for walls and floors; this book requires a previous understanding of general construction to utilize properly.
- • "Building with Straw Bales." Appropriate Technology Vol 32.No 4 (2005): 69. 13 Feb. 2009 <http://www.researchinformation.co.uk/aptearch/Oct-Dec%202005%20p/html/Oct-Dec%202005%20p_69.html>.
This short online journal sheds light on straw bale building. Written as an overview this article describes the advantages and shortcomings of straw bales. It speaks of straw bales life span, resistance to pests, fire resistance, and insulation properties. Gives a brief history of the long lived tradition of using straw in building around the world.
 Web source-
- • "Cob, Earth bags, Cast Earth, Paperboard, and Straw-Clay Mixes - Real Goods Solar." Residential Solar Panel Installation and Solar Power Systems for Homes - Real Goods Solar. 15 Feb. 2009 <http://www.realgoodssolar.com/solar/p/Architecture-and-Building-Materials-Part-4.html>.
This web source taken from the Real Goods website provides brief overview and opinion of different natural building materials. Materials include cob, earth bag, cast earth, straw clay, and papercrete. A short history is included with the different methods as well as description of code restrictions and/or patent information. This page is a brief that contains little to no process description but does include links throughout the page to more in depth explanations and other literature on the various topics.
 Contact Details
Myles D. firstname.lastname@example.org Arcata, CA