ferrocement

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Maybe this question has been addressed, but, if so, I can't find it. Does anyone have any direct experience with ferrocement. I have found a few websites, mostly dealing with generalities with Third-World construction, plus a couple books. I have only found one reference so far where someone has said, "This works for me."

In particular, I am interested in building a work-storage shed for stationary woodworking machines. My location is south-central TN. The soil mostly sand and clay with a lot of rock (chert, hard and sharp) and percolates well. I am thinking of erecting a stock-panel skeleton (like the tarp-covered barn in the recent Countryside), covering it with house wrap, then laying down 2-5 layers of chicken wire, followed by a mortar. The shape would be a hemicylinder about 20 feet in diameter (width) and 10feet high, more or less. The length would be determined by (a) the number of stock panels or (b) reusing the stock panels as forms by moving them along the structure. My plan is to start with 6 panels (two tied end-to-end) for a lenght of about 14 feet. After the chicken wire is down, go along the bottom 4 feet on both sides. Then put in a shelf on the outside and start working up. Eventually there will be 2 shelves, the top one for holding some topsoil and plants, both for food and cooling in the summer. The ends will be made of plywood or, if I can figure it out, papercrete. Windows will be in the ends. The location is on the NW side of a hill that has been bulldozed flat (about 50x75 feet) in a "holler". Water and electricity are abundant. I am essentially the sole source of labor. I can join furniture, weld, etc. but have no construction experience. My guess is that construction would take about a month hauling cement in buckets, the tradeoff being labor for cost.

My questions are as follows. (1) Do I need a foundation? Could I just dig down about 12-18 inches (max max frost depth) and pin the structure down with rebar or T-bar? (2) How many layers of chicken wire are enough? Too much? One-inch or two-inch? (3) I read somewhere in this forum that galvanized steel forms bubbles with wet cement, greatly reducing strength. Is this so? It would seem to preclude using chicken wire, which almost defines what ferrocement is. (5) Will this structure be as low-cost as I think. Locally, stock panels are $14 for 4.5x16 feet. Chick wire is $56 for 1-inch, about half that for 2-inch, per roll. House werap is about $100 per roll, but I have many usese for that. I have a fair amount of wood, mostly green oak. The only "new" tool I can anticipate is a cement mixer for about $250 new or less if I can find plans for an old drum and motor job.

The structure should be strong enough. Somewhere on the web I found a theoretical analysis of this type of building where the author calculated the minimum thickness to withstand 2 feet of wet snow load should be 0.008 inches (or was it 0.0008", not sure) for fully cured cement-wire, assuming it was homogeneous. Normally I'm leery of these analyses (having been guilty of a few myself), but I think it is doubtful he could have been off by a factor of 1000. The "rules of thumb" I recall are 0.5 to 1.5 inches of thickness for a hemicylinder (quonset) shape.

I've been thinking about this question for a while and if I posted something earlier here or elsewhere and you, dear reader, answered, I'm sorry. I spent most of the day tring to find what I remember posting and have been unsuccessful. So I decided to start my own thread.

Thanks for any advice and I would be very grateful for personal experiences with ferrocement, or, as it used to be called in less pretentious days, "cement over chickenwire."

Thanks again,

Marty

-- Marty Boraas (boraas@miliserv.net), January 22, 2001

Answers

Sounds like a fun project. There is a company in Colorado doing houses with a similar concept Their site might give you some ideas. The site is:

http://www.formworksbuilding.com/

-- Lynn Goltz (lynngoltz@aol.com), January 22, 2001.


Try www.ferrocement.net

-- Gina NM (inhock@pvtnetworks.net), January 22, 2001.

I subscribe to "eGROUPS papercretenews" and a recent posting listed this web site along with access codes. I found it real interesting, the site that most identifies with your posting is"storag~1.gif" Here is the listing as I received: www.driveway user id: ferrogroup, password'' wetmud. Hope this is interesting to you, I know it was for me. Wayne Roach P.S. also look at the eGroups that I mentioned it is really great!!!

-- Wayne Roach (R-WAY@msn.com), January 27, 2001.

extra note I forgot, it is www.driveway.com I forgot the .com

sorry

-- Wayne Roach (R-WAY@msn.com), January 27, 2001.


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