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Since this is a DIY forum I figured I might post a project we done did last summer. Never know, might inspire someone else and it's always a good idea to pass on lessons learned from actual hands on experience.

Well, it was time to replace the old tool shed.
Despite all the framing I'd added, the serious snow loads we get up here had finally damaged our old Montgomery Ward metal garden shed beyond the point of no return.

The wife wanted to throw up a simple pole shed, using up all the scrap lumber we have laying around. I wanted to add on to the cordwood wood shed using more cord wood and mortar.
I didn't want a crappy metal clad pole shed in my back yard, and the wife didn't want to put the effort in needed for mortared cordwood.

Also on our list of things to eventually do is build a ferro-cement dome for use as a guest cabin, and my wife was bugging me to get rolling on that project. So, we decided that a ferro-cement tool shed would be a good introduction to this building technique, letting us learn ( read that as make mistakes ) on a smaller scale non-critical project. If this shed holds up to our snow loads and is water proof, then next year we'll build the dome.

My contribution to the art of ferro-cement building is the use of inexpensive 16' long cattle panels for the frame work.
Ever since I first transported a few of these panels bowed up in the back of my pickup truck I have been fascinated by their potential as building material.
The steel is stiff and springy, easily bowed into useful shapes.
Barrel vaults! Domes! Covered wagons! Simply had to try it out.

The cattle panel frame -



We used the better part of three full panels to frame the shed up.
I'd intended to weld it all together but simply wired it up instead, because I couldn't get the welder I'd borrowed started!

We had a small cracked 7' x 12' concrete pad where the old shed stood. I dug a trench around three sides of it, maybe four inches wide by six deep.
The cattle panels were cut to length with bolt cutters. One end was shoved down into the trench, the other was nailed to the woodshed. The trench was filled with concrete to lock the panels in place.

The doorway presented a problem. It simply had to be sturdy enough to maintain it's shape when the cattle panels were nailed to it. I framed one up of 2x4s and that didn't do it. The next I framed up of 2x6s, and that didn't work. Finally I set two cedar posts in concrete, and that worked fine.
The rear window frame simply rests on the cattle panels and is wired in.

The cattle panel frame is covered on the outside with chicken wire, and a layer of 2.5 pound lath on the inside.

We soon discovered that the job of tying the chicken wire down and the lath up was a real chore!
First you cut a pile of short lengths of stiff wire, bend them into a U, and someone pokes them through from one side while the other person twists the wire up with pliers. Because of the huge number of ties needed this is a big job. It takes a long time and your always poking yourself with sharp bits of wire.

My wife had the wonderful idea of using plastic wire ties instead of bits of wire. Once we started doing this the tying went several times faster.
So, this handy tip is her contribution to the art of ferro-cement building!

Tying the top portions of the covering was difficult because you can't walk on top of the frame. We had to lean off ladders, or lay on the roof of the wood shed to get the job done. I have no idea how to do this with a barrel vault or dome, unless one uses expensive scaffolding.

Ties everywhere! -



The finished frame, chicken wire outside and lath inside -



Now it was time for plastering. I used a standard ferro-cement mix of about one part Portland cement, one part water and three parts sand. I used 1/8 inch minus sand that was available locally. Masons sand would probably work better. I was hoping we could get away with one layer on the exterior, so we dribbled some red cement coloring into the water as we mixed.
Yet more ties had to be added here and there to prevent the chicken wire from sagging.



The adults on my volunteer plastering crew thought I was crazy, and complained of to dry a mix, to wet a mix, it isn't sticking, dropping more on the ground than getting on the wall, and why-can't-you-build-normal-stuff-like-everyone-else-anyway? In other words, all the usual adult hang-ups.



The kids had no trouble and dove right in. Being kids, they still knew how to play with mud and have fun.
I had three adults and two kids plastering, and a lady measuring out water and Portland.
Naturally I just strutted around, swilling coffee, waving my arms and shouting "Plaster me hearties plaster!!"
OK, so I was really shoveling sand and mixing the whole time...



After about a hour we stopped for a coffee break. When we got around to getting back to work the crew went into overdrive and I didn't turn off the mixer once, I could barley keep up with them.

At one point the weight of the wet plaster started to buckle the cattle panel frame. "Shhhh, don't tell Bob!" was the instinctive reaction of the hardworking, dedicated and professional crew, but my loyal wife, who also had to live with the finished product said "Go get Bob go get Bob!!
We had to shore the interior up as we went along. I had really thought the stiff bow of cattle panels would hold the weight.



Plastering the top was just as hard as tying the top portions had been, because you can't climb on the surface. But toweling down the plaster got easier the flatter the curve got.



But eventually the job was done.
This is what the interior surface looks like. I had originally experimented with using burlap material for the inside covering but couldn't make it work out, so used the more expensive metal lath. I'm glad I did. The walls were flexible enough as it was which made plastering difficult on the vertical walls.



It rained that night, perfect weather for curing cement, but the shed proved to be full of holes.
My new mud hut -



Over the next two weeks my wife and I added two more coats to the outside, trying to waterproof the structure.
These additional coats were much easier to trowel on, and I started adding about four soup can full of lime to the sand and portalnd mix to make it more plastic.

Plastering the interior wasn't to bad, except for the fact that the Red Top gypsum plaster I purchased must have been to old and exposed to damp storage conditions. Instead of about an hour working time, I got fifteen minutes to work with each batch before it hardened. So we did small batches.
Plastering up-side-down was interesting. The plaster consistency is rather like a thick frosting. Ever frost an up-side-down cake?
The plaster adhered well, but hardened so fast I couldn't get a very smooth finish. When done plastering, I white washed the interior with lime and water.



Front of the shed. Note the little Harbor Freight solar shed light




Inside the shed.




I'm glad we built this little shed and I think it will last a lifetime, but I do not think I will be building a guest-cabin-dome out of this stuff.
I find that the ferro-cement structure is very hot in hot weather. The thin shell absorbs the heat of the sun and re-radiates it into the interior. It's also cold and damp in cold and damp weather. Not good for a structure to be inhabited. The roof, though strong and fireproof, isn't as waterproof as I'd wish it to be, and the amount of labor needed to construct one is excessive.
I think I'll stick to stucco for walls, and sheet metal for roofs.
 

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You did a fantastic job on that project sir! What a great post. That gives me a couple of ideas actually. Good description, good pics, and looks like a great family you have there as well. Appreciate the post!
 

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thank you for the post.

Ok, now the row boat.

I first learned of Ferro Cement years ago after reading about a man who built a 40 foot sail boat.

I was in awe of this way of building.

I set out to learn all I could. I kept hearing of scratch coats and shell coats and did not know what people were talking about.

I ask some workers who had been plastering for years and they could not tell me.

I will tell you what I think it is.

The scratch coat is just plain cememt, NO color, and they plaster with light groves or "scratches" in the coat so that the next coat applied will hold better to the old coat.

The shell coat, it a light layer of COLOR (added) cement placed over the scratch coat.

It can be 100 percent cement with no sand, this is what makes the coat more water repellent. All concrete (cement) will absorbe water to some extent.

I know I am ;most likely the only one in the world that did not know the above info, but just thought I would pass it on just incase.

Later
wayne
 

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That's a nice shell. With fero cement, I generally make a cage of 1/2" rebar and tie it together in a cross hatching that makes 12" squares, backed on the inside with wire mesh. Tying this rebar into a good concrete foundation and shooting the concrete through a Mayco pump with an air compressor allows you to make 6-8" thick walls. This, of course is much more expensive then your method, but it will not sag when loaded with wet cement and has good insulation properties. If you have ever seen a swimming pool being built, it is very similar. Your project has a definite charm and is very appealing. Great job!
 

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Great Post!
A question or two if I may?
What would you say your total dollar investment was?
How long to do the job, start to finish?

Thanks!
 

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and shooting the concrete through a Mayco pump with an air compressor allows you to make 6-8" thick walls.

How much does a pump like this cost (where to get them) and how much working air pressure is required.

What is the sand to portland ratio for pumping concrete

Later
wayne
 

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Ferro Cement Expert

is Mr. Lou Watson, West Sacramento. Calif. He built an entire series of ferro cement 55 foot boats called Vallejo. Try him. I owned one---. Coat the exterior with two epoxy coats and you are waterproof. It can be done well as you have just learned.
Laus Deo
overbore
 

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Used Mayco pumps and the large air compressors cost about $10k each. You can rent them from equipment rental shops. Mayco pumps move too much concrete for you to keep up by hand mixing. The air pumps normally run about 100 to 120 PSI depending on the thickness of the mix. Have the cement delivered by truck and pour it into the pump directly from the truck. The cement company mixes a special mix called "Mayco Mix" which is a bit smoother than normal concrete. All this, of course, is for a big project such as bunkers or underground houses.

If you are going to mix by hand, then 1 to 3 or 1 to 4 ratio is good.
 

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Ferrocement is just steel reinforced cement. Cement is very versatile and can be applied thin or watery as well as thick. Stucco guns will work theoretically, but you must look at the size of the spray hole. Some sands and fine gravel used are too large for the smaller holes in these sprayers. If you have an old stucco sprayer, drill out a larger hole so the thicker concrete mixture can come out and it should work well.

Concrete uses gravel as its structural base for strength and gravel won't spray well, so you need a thinner mixture. You need to replace the missing gravel with more steel like rebar, 6x6x10 wire or lathe.
 

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Ferrocement is just steel reinforced cement. Cement is very versatile and can be applied thin or watery as well as thick. Stucco guns will work theoretically, but you must look at the size of the spray hole. Some sands and fine gravel used are too large for the smaller holes in these sprayers. If you have an old stucco sprayer, drill out a larger hole so the thicker concrete mixture can come out and it should work well.

Concrete uses gravel as its structural base for strength and gravel won't spray well, so you need a thinner mixture. You need to replace the missing gravel with more steel like rebar, 6x6x10 wire or lathe.
Have to be a hell of a man to hold a stucco gun filled with concrete...
 
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