Earthbag Kindergarden, ROCHA URUGUAY

ESPACIO DE LOS NIÑOS – 2011 – TIERRA COMUNAL – ROCHA – URUGUAY

In June we were busy in Rocha, Uruguay  designing and building a Kindergarden – from our favourite building material, Earthbag! We were asked by the ‘Tierra Comunal’ in the Sierras of Rocha (Naturalezarte.com) to come and design and start building a kindergarden and play space for the children.

It was a wonderful experience and we made many new friends – hopefully this building will start the Earthbag building revolution in Uruguay! A huge thankyou to everyone who helped out and was a part of this process. See here for more info about the project and photos from our month there.

We originally intended to use our Brazilian system ‘Hyperadobe’ but as this continuous open-weave tubing is unavailable in Uruguay we decided to go with ordinary large fruit sacks, which is what the tube is made from anyway. So here was perhaps a world-first – not Hyperadobe, not Superadobe, but a new hybrid – what shall we name this version I wonder?

The sacks worked perfectly well even with our very sandy soil we were using and are really a great option to those who would like to use less plastic while still providing the strength and stability of the grain sacks. You can also reuse old onion bags if you have the time to source these, as often they will be free – just try to make sure they are all the same size!

We were also determined to use Zero Concrete in our foundation. This equated to more work, but eliminated the need to hire specialist concrete contractors and use unnecessary bags of concrete – and this is one of the great advantages of Superadobe/Earthbag building – you can rethink traditional types of foundations because the dead weight of the structure provides much of the stability. Also concrete can crack when used on soil with a high clay content when the clay expands and contracts from season to season – which is the situation we were faced with here. The system we decided to use instead was bagged gravel. For this we dug out a trench to a depth of around 50cm or until we hit more stabile earth and allowed 80cm for the width (I like to use the width of the sacks – 50cm – plus an additional 15cm either side to help with drainage and condensation). We filled and lightly tamped this trench with gravel until about 15cm below ground line. Ideally you should use larger rubble/rocks at the bottom and then a finer grade of clean gravel (min. 2cm size) but we could only source dirty gravel and sand of various sizes…nevermind! This worked fine as well. We then filled white feed sacks with the gravel/sand and placed them in the trench, tamped them and added two more rows on top tamped each time. This was our stem wall/foundation finished! Because the gravel was quite dirty we added a vapour barrier on top of this for any condensation/humidity that does manage to work it’s way up to where the walls begin, but you shouldn’t need to use this.

After this the fun part began! Santi our main man managed to source some gorgeous purple fruit sacks to use – so combined with the white bagged foundation and the rocky serra backdrop behind, earthbags never looked so good! These were filled with our sandy reject sand dredged from the nearby lake – the second greatest thing about Earthbag – you don’t have to be too fussy about your soil mix, and this sand dried as hard as a rock to our surprise – we started the building process like every conscientious earthbag builder should – testing all the different soil types in the area by making test bags, as this is the only way to truly know your soil and how it will respond – bag it, tamp it and leave it a week to dry.

The following are some photos of the experience there – will upload more when it’s finished!