Posted by: iainjhunt | August 8, 2011

Ferrocement: The coolest invention since the smart phone

The best things in life aren’t things, nor are the most interesting. As you might have read, my last two blog posts focused on people, from El Guabo’s dynamic doñas Modesta and Lupe, to hardware store owner Don Chico. Personal stories are certainly the most interesting, and this work is first and foremost about people. However, this time I’m afraid I can’t help but tell you a story about a thing, or rather an idea that made its way from Bolivia to the Dominican Republic to become a thing we’re proud of down here, Waslala’s first ferrocement water tank, constructed in El Guabo.

So what’s so special about this thing? Well, one of its most exciting properties to Water for Waslala donors and beneficiary communities alike, is that it requires a fraction of the materials required for the ubiquitous poured concrete tanks most commonly used in Waslala. That means less stuff to haul to sometimes difficult-to-reach locations, and of course reduced construction costs (on the order of about 50%). Construction of a ferrocement tank is also participatory, requiring many hands, giving a community a greater sense of ownership. Ferrocement fun fact: the technique was first used in the construction of boats back in the 1800s.

So what is a ferrocement tank? As one might extrapolate from the name, the essential elements are iron and concrete (or more correctly, mortar). You can think of it as a rebar and chicken wire skeleton to which several layers of motar flesh are applied. Other ingredients include a sealer (liquid concrete additive to prevent leakage) and mucho cariño (love). Ferrocement walls should be no more than 6-7cm thick, causing some serious raising of eyebrows and shaking of heads when mentioned to many a mason unfamiliar with the technique. As the cliché goes, you gotta see it (or build it with your own hands) to believe it.

I first took then chance on ferrocement while working on a community water system in the Dominican Republic. The current director of Peace Corps’ appropriate technology sector in the country (and an influential mentor of mine) had recently arrived from Bolivia, where he had years of experience in ferrocement construction, mostly for rainwater catchment systems. The community where I lived and worked was selected as the test site for a pilot ferrocement tank/ ferrocement construction training for Peace Corps volunteers and their community partners. From there it spread like peanut butter and jelly. Local government offices began to seek out and employ our masons to build their own ferrocement tanks. And here in Waslala, I can foresee the same phenomenon taking off, with the mayor’s office (albeit independent of our own efforts) planning on incorporating ferrocement in upcoming projects. Ferrocement: it’s the coolest invention since the smart phone (note: author doesn’t really know what a smart phone is).

I’ll let the following photos walk you through the ferrocement tank construction process:

Preparing plumbing and rebar to pour the floor (Day 1)

Denis and Juan finishing the floor (Day 1)

Tying chicken wire to soldered rebar grid to serve as wall skeleton (Day 1)

Standing up the skeleton (Day 2)

Tarp tied around outside of skeleton to serve as temporary form to apply first layer of mortar inside tank (Day 2)

Denis applying first layer of mortar (Day 2)

Continuing with first layer of mortar (Day 2)

First layer of mortar revealed after tarp has been removed (Day 3)

Application of final inside finishing layer, outside layer having been completed bay before (Day 4)

Construction of temporary log structure to hold up false floor (Day 5)

Tying rebar and chicken wire for roof (Day 5)

Finishing the roof (Day 5)

The final product, freshly painted to match the colors of the Nicaraguan flag



  1. […] this past month, in the village of El Guabo Jicaral. Iain Hunt, our Waslalan project manager, replaced concrete with ferrocement for our storage tank and tapstands, saving us $10,000 in construction costs. Also, El Guabo is the […]

  2. […] introduced innovative solutions (built our first ferrocement tank!), […]

  3. […] have provided clean drinking water to 2,500 people strong (to-date). Last year we first implemented ferrocement technology to better fortify and control the cost of our systems. And this year we’ll be distributing […]

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