New Earth Plaster tests

We are currently making lots of different Earth Plaster blends. We had a Mexican ceramicist, Christian, residing with us for some time who started experimenting to find the perfect mix. He refined this art-form and developed a technique that was extremely strong and durable but mostly using Lime, or ‘Cal’ as a stabiliser.

We are now trying to eliminate the lime; firstly so as not to deplete our earth’s natural resources but also because another direct effect of lime when used in plaster is to reduce the ‘breathing’ effect, meaning in this sense, the ability of the plaster to absorb humidity from the atmosphere and re-release it – this controls not only the humidity of course but also the ambient temperature which in hot climates becomes greatly reduced; in cool climates warmer, or more constant.

One beautiful ingredient Marcelo has been using is ‘Taboa‘, a type of marsh reed, the seed heads which can be pulled apart to create a binder similar in appearance and texture to cottonwool. It takes a bit of time to blend it fully with the mixture but the result is well worth it.

One wall we are working on at the moment is the interior of the Adobe Dome, constructed by us in an Earth Building workshop held by adobe master Gernot Minke in late 2009. The foundation wall, holding up the adobe dome is concrete block, over which went a simple clay/sand plaster mixture. It has held up quite well over the past 1 1/2 years needing only a small amount of patching up. The finished appearance however was quite grainy so we decided it was time to give it a bit of a makeover. Now we have applied this Taboa mix and will see how it holds and how many cracks develop over the coming days and weeks. It is a deep chocolate colour in appearance and when buffed with a trowel or spoon really enhances the shine of the mica flecks which are abundant in this area.

The formula we used was as follows:-

• 1 volumetric part clay
• 1 volumetric part sand
• 1/2 volumetric part of Taboa seeds
• 1/2 volumetric part earth
• a small amount of cow dung (we used just 1 bucket for this mix, with 1 ‘volume’ being 1 wheelbarrow)

Next for the walls in the Dome we will reapply this mixture if necessary, and then above this we will use some beautiful white clay we have here to create a decorative band. We are trying out mixing Tumeric and also Urucum in with the clay to get different natural tints. See the page under ‘Plants’ on how to best extract the colour.

First Earth Floor Experiment

In ‘Vietnã’ (a place in Tibá where we try out every new technique) we have been experimenting over the years with the best way to make a natural floor at the base of the small earth hut we have there. Due to the location and the fact that it is subject to a lot of moisture and rising damp Marcelo, earth-builder extraordinaire, has finally taken on the challenge and taken the whole existing floor out and started again from scratch.

First he laid down a lot of old tyres, to build up the foundation again to a reasonable height and then filled in between this with old bottles. This was to provide bulk between the tyres and also to make use of the old bottles. Around the rock strip-foundations under the walls some asphalt sheet was nailed into place which will stop moisture from the sides entering by capillary action; this will be heated later to bond it better to the stone foundations.

Next was laid coarse gravel, tamped lightly and then hosed down. The first earth mix was laid over this very roughly, to a depth of around 20mm and just consisted of mixture of just sand and clay.

Next a large adobe bed was made from the usual sand, earth, horse manure and also a lot bamboo leaves added in. A level was carefully set and then this new mix was then laid over the other layer which had been left to dry overnight.

We are now waiting for this giant adobe brick to dry – which as there is no direct sunlight on it will take up to a month – before adding the last layers and the decorative infill adobes – check back to see our progress!

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Jorge Belanko confirmed in Tibá for July!

We are very excited to announce that earth construction expert Jorge Belanko is confirmed for July to teach a week-long course in Tibá on Natural Building (see www.tibarose.com for more details).

Jorge is a world leader in earth construction technology and the course will cover many different techniques such as Green Roofs, Earth Building (Adobe, Cob, Wattle and Daub, Natural Plasters and Paints) as well as Permaculture building principles such as passive solar design and trombé walls.

Have a look at the extract from the video “El Barro, Las Manos, La Casa” below which comes from a feature-length how-to building documentary made in the region of El Bolsón, Patagonia, Argentina and describes the various techniques and technologies involved in building your own earth house.

Keep checking back here as we post more details of the course and we hope to see you here in July to learn from the master himself!

Jorge Belanko Filme Construção Natural

 

5,679 Adobes and Counting!

So far on the ‘Lookout House’ we have made and used nearly 6000 Adobe bricks – of two different rectangular sizes and also some beautiful African style bricks.

Also we finally put the two internal arches up on the 2nd of Feb, which are currently settling and drying for a couple of weeks before we remove the formwork underneath – this has been a long process from the conception to getting them in place! See more about the progress here and pics here in the February update…