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How Chicken-wire and Concrete Solved My Problems

continued

by Mark S. Chenail   

The quality of cementing materials deteriorated and the use of concrete died out during The Middle Ages, as the art of using burnt lime and pozzolan (admixture) was lost, but it was later reintroduced in the 1300s.  During the Renaissance, the manuscripts of the roman architect, Pollio Vitruvius, were discovered in a Swiss monastery and concrete was once again widely used as a building material.  The 18^th century saw the development of Portland cement, hydraulic lime and concrete for use under water.  In 1818, a British engineer, Ralph Dodd, took out a patent introducing wrought iron bars into concrete and in  1867, Joseph Monier, of France, reinforced William Wand's (USA) flowerpots with wire mesh, ushering in the idea of reinforced concrete.   It’s this simple idea of a mesh of wire and concrete that eventually leads to our own down home favorite, chicken wire concrete.  Cement is at it’s strongest when it is less than ¼ inch from the steel reinforcing and it is the various layers of reinforcing that increases  the concrete’s ability to resist great stress.  The mesh as opposed to thicker rebar allows the creation of more fluid and less linear forms.

The standard rule for mixing concrete is 4 parts sand to 1 part Portland cement, plus sufficient water to give it a proper consistency.  Mixing concrete is a bit like making piecrust,  it isn’t an exact science.  Some days you will need more water, sometimes less.  Too little water will make the  cement crack, but too much makes it soupy and it won’t stay on the wall.  You just have  to work at it, until it feels right. Eventually you will get the hang of it.  Plain old 1 inch chicken wire is all you need for the reinforcing mesh.  The rolls come in various lengths and are generally 3 feet wide. The old-timers used a single layer and that is usually sufficient for most simple flat walls, but multiple layers are better for free form work or for roof structures that will take some weight or be self supporting.  Overlap the layers so that the openings in the mesh are as small as possible.  Twist the edges of the wire together to keep them from moving. 

                                                       Rough Coat in Progress

The next morning, I went round to my neighbors to take a look at the various examples of chicken wire concrete that they had to show me.  The first example was the simplest.  My good neighbor had used  chicken wire concrete to cover the old foundation under his house.  The  foundation was built of brick and was starting to show its age and there had been several cracks that were beginning to leak. He had stretched a single layer of chicken wire over the brick, stapling it to the sill plates at the top and  to the bricks themselves at the bottom.   He had then rough troweled on the standard concrete mix using a stucco trowel with a toothed edge.  He simply slapped it on working from the bottom and forcing it into the mesh and unto the wall.  He left the first layer a bit rough, the professionals call this tooth, and when the first layer had begun to set up, he put on a thinner coat with a smoother finish. When the finish coat had started to set, he brushed it down with an old stiff bristle broom, just to give it some character.  He had never bothered to seal  or paint the concrete and it had stood up to all sorts of weather for some 35 years.  Every few years, he went around and inspected the work for any cracks or failures and made minor repairs.  Repairs to the exterior chicken wire concrete weren’t much more difficult than spackling the occasional ding in the plaster inside the house.  The surface was extremely durable and took all the abuse that weather and man could send its way. 

My second neighbor was the proud owner of an ornamental fish pond that his father had built in the 1950’s as an anniversary gift for his wife.  It was meant to be a purely ornamental feature in the yard and had been home over the years to several families of goldfish and carp.  My neighbor had helped his Dad to build the pond, so was able to give a fairly detailed account of the process.   They had chosen for their site,  a natural little mound that already existed in the yard , a spot where the yard began to rise up toward the surrounding woods in back of the house.  He and his father had dug a hole about 3 feet deep and  maybe 8 feet in diameter .  Being a free thinker and not bound by the rules of strict geometry, the hole was rather free form,  and sloped a bit along the far side nearest the woods. Once the digging was done, they had put down a layer of fine sand and then covered the bottom with 5 layers of overlapping chicken wire, bending it up around the edges where it met the sides of the hole.  Five layers of chicken wire was perhaps overkill, but his dad wanted to make sure that the bottom wouldn’t crack or leak.  He also had the forethought to install a length of drain pipe,  so that the pond could be drained if necessary. They then covered the wire with concrete and let it set up solid, making sure that the turned up ends of the chicken wire remained accessible so they could attach the sides. When the base was solid, he and his Dad had spent a couple of days building up the sides of the pond. They had put a bit of sand down to make a cushion and then wired sections of mesh to the ends that were left protruding from the bottom.    

They left the wire overlapping the perimeter of the pool and added two more layers, until they had a shape they liked and a fairly solid form.  They then applied a slightly richer mix of concrete, 3 parts sand to 1 part Portland cement and troweled it onto the sides of the pond, merging it with the edge of the bottom.  They made the joint a bit rough to make sure there would be no leaks,  but still managed to get a relatively smooth surface.  They brought the concrete up over the top  to form  a rough border around the pool, which they ornamented with flat stones.   A short length of pipe was set into the wall of the pond and left to protrude as a runoff drain.  The runoff drain keeps the pond from overflowing its sides in heavy rainstorms.  Once the concrete had set up completely, his dad had painted  the inside with  black pitch to seal it and make the water look deep and cool.   After it was embellished with water lilies and other ornamental plants, it became the focal point  of the yard.  My neighbor says that it has never cracked or shown any signs of leakage and feels certain that it is so heavy that there is never a problem from frost heave.   His only complaint about the project was that by the time they had twisted together all the necessary layers of wire, their hands were cut to shreds, but admitted that wearing gloves would have made the task even more difficult.  Sometimes you have to suffer for your art.

The third chicken wire concrete project was definitely the most impressive.  It was a literal tarpaper shack,  that had been completely covered in chicken wire concrete.   The shed  was about 10’ x 12’ with 8’ walls.  My neighbor had set  4x4 treated posts in the ground at the corners and then hung  2x8 rim joists about 8 inches above the ground.  The floor was laid on 2x8 joists set on 2 foot centers and floored with old pallet boards.  The walls were conventionally framed with 2x4 stud walls and had a shed roof of 2x6 rafters.  So far this was standard building procedure,  but from this point on, it was less conventional.  Rather than go to the expense of sheathing, my neighbor than covered the walls with plain old tar paper, rolling it out over the studs and stapling it down as tightly as possible.  When the walls were covered,  he then stapled up some thin lengths of lathe to give the tarpaper surface some rigidity.  The lathes were set  about  6” apart.  Then he had stretched two layers of cross lapped chicken wire over the tar paper and lathes.   Once the walls were complete, he had troweled on the usual mix of concrete, forcing it through the mesh and unto the surface of the tarpaper, taking some care not to tear the tarpaper.   It had taken him and a friend the better part of two days to concrete all four walls and to get a decent finish on the walls.  Even with just tar paper backing and 2 layers of chicken wire mesh, the walls are surprisingly strong.  He gave them a semi rough texture with the trowel and a stiff bristle broom.  Eventually, he painted the concrete,  but this was purely an aesthetic choice.  The raw concrete is completely weather and fireproof, but it isn’t particularly attractive in its basic state.

The real surprise was the roof, which had been made using the very same method.  After setting the rafters, he had stretched tar paper across them  and turned it down over the edges of the rafters.  He had then nailed on the thin lathes like purlins, followed by five layers of chicken wire, cross lapped  to make the smallest openings possible.  A wooden edge of 1x3 was then nailed onto the face of the rafters to create a small form to hold the concrete,  cover all the wire ends and make the edge neater in  appearance.  The concrete was mixed a bit thinner than it had been for the walls, so that it would flow more easily and give a smoother surface finish.  The concrete was brought up in buckets and poured over the chicken wire mesh.  A stucco trowel was used to spread a thin layer of concrete over the whole roof surface and to force it into the mesh.  It was then given a smooth finish with a standard mason’s trowel.  After a few days curing time, he painted the roof with concrete water proofing as an added precaution.  The whole structure is virtually fireproof,  the roof is completely waterproof and will easily support the weight of several  grown men.  All in all, it gives a whole new meaning to the idea of tar  paper shack.

After seeing these examples of chicken wire concrete, I am convinced that this will be the method I use to finish my two chimney stacks.  As they are already sheathed with OSB and tarpapered, it is only a matter of stapling up the chicken wire and troweling on the concrete.  It won’t be a small job, but I figure it can be done in sections and that a rough and ready finish will probably be a better solution than  a smooth troweled surface.  I’m not sure how I will finish off  the tops of the stacks.  I may cap them with sheet copper or metal, which will give a rich effect, but I may attempt to do it with a built up edge of concrete and chicken wire instead.   I think before I send the boys up on the roof, we may built something smaller on the ground as a practice exercise.    Maybe when we get our well installed this summer, we can build a little well house to learn the finer points of chicken wire concrete.  From all I have seen, it’s simple and durable, it uses common and easily procured materials and best of all its inexpensive.  Sounds  like a  perfect solution for many homestead building projects  in my book.

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