Skip to Content.
Sympa Menu

homestead - [Homestead] Stumbled across new term---Cobwood

homestead AT lists.ibiblio.org

Subject: Homestead mailing list

List archive

Chronological Thread  
  • From: tvoivozhd <tvoivozd AT infionline.net>
  • To: homestead AT lists.ibiblio.org
  • Subject: [Homestead] Stumbled across new term---Cobwood
  • Date: Fri, 04 Feb 2005 17:17:41 -0500

*Visit the www.dirtcheapbuilder.com <http://www.dirtcheapbuilder.com> WebStore where you can order 200+ favorite & one-of-a kind books right online, securely.*


Taylor Publishing, Cutten, California

Cobwood


*Alternative and Free Materials:
Papercrete Ideas continued....*

In Earthworks (July/August 1999) I described the new Papercrete material made of newspaper and cement, and mentioned a more earth-friendly recipe I prefer called "Cobwood,"which is made without cement. Cobwood is basically sawdust added to clay, lime and sand, with dry grass clippings or straw for tensile strength. I use it as a soft, sculptable building material, much like Cob- the ancient Welsh earthen recipe. Cob is a mix of sand, clay and chopped straw hand applied in loaves­ the "cobs"­ to build a wall. Cob is also similar to Adobe mixes in which a ratio of 30% clay:70% sand is considered ideal. These natural materials have been used, in various proportions, for many enduring structures the world over. *Visit this Papercrete information page for basic instruction <http://www.northcoast.com/%7Etms/papercrete.html> *

*Many materials can be used.*
People who are looking to use unprocessed and indigenous materials, are experimenting with harvested clay, sawdust, woodchips, hemp, weeds, straw, dry grass, and lime, forgoing the high embodied energy Portland cement altogether.

Agstone

/Hillside steps made of Agstone/
The mixes I experiment with have ranged widely, with satisfactory results. I am not attempting to use Cobwood for load bearing walls, or for critical structural areas, and I am not a construction engineer or architect. However, these natural materials have been used since the beginning of man's (and woman's) shelter building attempts, and are easy to play with for anyone interested in exploring alternative ideas.

*And that is the beauty of using nature's gifts...free and readily available, unwanted and uncommercialized, with no profit in restricting your access to grass, weeds, river or beach sand, clay or rubble. In fact, clearing away scrap shrub and weeds is seen as an improvement to most property!*
Most of what you need can be found in your own back yard, down the road, or in a local field or stream. The only item which must be purchased is hydrated lime, sold in 50 pound sacks, available at most builder's supply and home improvement retailers, or feed & grain stores, and costing about $6-$12 .

------------------------------------------------------------------------
You may have a perfect 30:70 subsoil on your property. This is great for making traditional cob, or for adding sawdust and lime to make Cobwood. Experiment with what you have, make test bricks, and handle the material to see how you like using it. As with papercrete, there is no one right way to make it, and your available, indigenous materials may dictate your final results.

------------------------------------------------------------------------
Compost

/Compost bin walls are made of a three layer pour of Agstone, using board formworks./

------------------------------------------------------------------------
Agstone maker, John Stahl, uses dry chopped weeds, shrubs, branches and donated hemp stalks as his filler material. Industrial hemp stalks, available in Canada and France, and weeds (available everywhere) make a great free filler. Dry brush, shrubs, teasel, yellow dock, even pine needles can be finely chopped and used. John Stahl has tossed newspapers and magazines into a wood chipper/shredder and used it along with weeds to make Agstone.

shredding

/A professional wood chipper is used to chop and shred materials./ What is amazing is how simple it is to use these dry unwanted materials and create something practically for free. Clearing a weedy, overgrown, and hilly property could provide the filler material, and back-hoeing to make a level building spot can provide the clay solving two problems, and recycling two ingredients at one time.

The three primary ingredients of Cobwood are mixed while wet, and all are measured by volume. I use a basic recipe of 9-3-2-1 and work the mix into a 5 gallon pail. Nine wetted, aged sawdust (soaked overnight, then drained for a few hours), three clay slurry, (thick as sour cream), two lime putty (also like sour cream), and one sand, usually dry. I¹ve made mixes with sand and without, and prefer the smoother texture when sand is used, as it fills in the voids between sawdust grains; more sand can also be used. Dry chopped grasses are added last before building. This pliant material can sit overnight, or for a day or so; is like a wet cob, and can be poured, hand applied, or thrown, "harled" as the Scots do with exterior renders, (wear protected gloves).

My Cobwood mix is high on sawdust because it is both freely available, and comes ready-to-use, with no chopping necessary. Redwood sawdust mixed with gray clay produces a soft gold or honey color. When completely dry the surface is dun colored, very hard, and only slightly friable. A nail or stick can scrape marks in the surface only with strong pressure. Mixing is done by hand with a garden hoe, and clay is often slurried first with a paint stem mixer attached to a 1/4 HP hand drill. For larger construction projects a cement or mortar mixer can be used.
DRILL

The outdoor garden bench I built is made entirely of various experimental Cobwood mixes poured over a rubblestone base of broken concrete chunks. Mixes were added one pail at a time, and left to dry. Hand shaping of the back, arms and seat was not difficult, and a form could have been used to build the base quickly. The design for a bench or seat can vary widely, and could take any shape. Curved driftwood can be used for the arms, river stones can stud the base and seashells or other elements can be embedded into the bench for more personal, creative expression.

*Endurance*
A brick, or wall, or garden bench left completely exposed to driving rains will begin to return to the earth. If lime was used in the mix any rainwater will cause less damage, but building under a tree for shelter (as with my bench), or plastering a wall for protection is best. I have no experience with freeze/thaw cycles on my Cobwood, however cob houses in England and Wales have endured for hundreds of years through extremely harsh winters. These houses were rendered with pure lime plasters and have stood the test of time. John Stahl does get below freezing temperatures in the mountains of Leggett CA, and both of us endure long, very wet winters, and these natural materials have stood up well.

Traditional cob will also perform well, and saves adding lime or sawdust to the mix. If you can locate good soil, or mix sand and clay together for a respectable cob mix you will have a totally free building material. Lime, cement, or purchased sand does add to the overall cost, but compared to other building methods (and the tools and equipment needed) Cobwood and Agstone are an inexpensive and easy to use alternative material.

------------------------------------------------------------------------
Please visit the Papercrete Information page <http://www.northcoast.com/%7Etms/papercrete.html>, or the Dirt Cheap Houses page <http://www.northcoast.com/%7Etms/cheap.html> to see more photos and learn more about really alternative building.

------------------------------------------------------------------------
Home <http://www.northcoast.com/%7Etms/elkriver.html> |How to Order <http://www.northcoast.com/%7Etms/elkorder.html>| Adobe and Rammed Earth <http://www.northcoast.com/%7Etms/adobe.html> |Stone <http://www.northcoast.com/%7Etms/stone.html>|
Straw bale <http://www.northcoast.com/%7Etms/strawn.html> | Cordwood & Timberframe <http://www.northcoast.com/%7Etms/wood.html>| Dirt Cheap Houses <http://www.northcoast.com/%7Etms/cheap.html>| Building with Lime <http://www.northcoast.com/%7Etms/lime.html>| |Cob & Earth <http://www.northcoast.com/%7Etms/cob.html>| Practical building books <http://www.northcoast.com/%7Etms/practical.html> | |Solar cooking <http://www.northcoast.com/%7Etms/kitchen.html>|Designing A Home <http://www.northcoast.com/%7Etms/design.html>| Small Projects <http://www.northcoast.com/%7Etms/small.html>| Off the Grid/Homesteading <http://www.northcoast.com/%7Etms/y2k.html>| Buy or RENT Building Videos <http://www.northcoast.com/%7Etms/video.html>| Heat:Stoves&Ovens <http://www.northcoast.com/%7Etms/heat.html>| New Books! <http://www.northcoast.com/%7Etms/new.html>| Good Used Books <http://www.northcoast.com/%7Etms/used.html>|

© Copyright 1999-2003 Taylor Publishing


*Visit the www.dirtcheapbuilder.com <http://www.dirtcheapbuilder.com> WebStore where you can order 200+ favorite & one-of-a kind books right online, securely. *

**www.papercrete.com <http://www.papercrete.com>**

*
*




  • [Homestead] Stumbled across new term---Cobwood, tvoivozhd, 02/04/2005

Archive powered by MHonArc 2.6.24.

Top of Page