The cistern, continued: ferrocement construction

In March I posted about working on our cistern. Since then, I’ve been able to work on it a few more days. My good friend Jon has come over to help in the construction. He’s actually helped with some other projects to and will continue to do so through the summer.

Before the cistern project, I had never attempted the construction of a ferrocement water tank. I first became aware of this type of construction through my dad who found information about it online. It seemed like a neat concept, so I did a little research on it myself. I found a book online that provides instructions. The strength of a ferrocement water tank is provided by a steel armature which is the plastered with a cement sand mixture.

At the time of my last post about the cistern, we had completed the floor framework and poured the concrete for the floor. I was concerned that the floor wasn’t going to set up as it was supposed to. It acted differently than concrete I’ve worked with before. But, it did set up quite nicely. So, construction has continued.

After the floor we began building the walls. The process involved putting welded wire around the perimeter. Then, we added vertical rebar and horizontal rebar. Then, we began framing the roof of the tank.

  The book details the building of a round tank. Because of where I’m building our cistern and the amount of water storage I desired, I decided to build an elongated tank. It is 9 feet wide and 14.5 feet long. I’ve calculated the cistern’s capacity to be 5,300 gallons of water. I changed the plans to suit my application, opting for extra steel in the armature to make sure the strength will be more than sufficient.

For the roof, we bent sections of 1/2 inch rebar that were wired into the frame all the way around. Each of these sections was bent as identically as possible. There will be an opening on top. Rather than make it round, I designed it to mirror the shape of the tank. It will be about 2 feet wide by 8 feet long.

Today we finished installing the rebar in the roof, including horizontal rebar. The next step will be to put another layer of welded wire on the inside of the walls and on the roof. Then, we’ll put on some poultry netting and expanded metal lathe before beginning the plastering process. It’s coming along nicely, but it will still take a few more days of work to complete it.