How to make adobe bricks - natural bricks from clay, sand and... horse dung!

Stomping around in a heap of horse dung. It’s not something I do every day. But when making natural bricks (so called adobes) this is a necessary part of the process.

We have gathered in Happy Valley in Benfeita, Portugal, where Prem and Roshni are building a bathroom with natural materials. Part of the walls will be made from a natural type of brick called ‘adobe’. These bricks are made from a mix of clay, sand, straw and some lovely horse dung. According to Bruno, who is teaching us how to make the bricks, the horse dung helps to provide elasticity to the bricks, making them less prone to crack. There are about 15 of us, plus a bunch of kids, and we are eager to get started.

Dancing in the dung

The clay, dung and straw are locally sourced, and because clay is different in every region, it’s important to make sample mixes with different ratios of the ingredients. Bruno calls them cookies, which confuses us, until he shows us a bucket full of them. Indeed, they look deceptively like mouth-watering chocolate chip cookies. We are advised not to eat them if we are fond of our teeth.

No, not chocolate chip.

Etched into each ‘cookie’ is the ratio of the main ingredients used for that sample.
Bruno prepared all of this in advance. He found that in this region the ratio for dunch/clay/sand has to be 1/2/2. He also already made the mixture for the bricks, with a cement mixer. It’s a huge pile, which we have to keep wet the whole day with a hose and work the water into the mix with our feet. Bring water, mud and a bunch of kids together and you know what is inevitable. Mud fight!

SPLASH!

Who said mudfighting is only for kids?

The adobes themselves are created by putting the mixture into moulds, that are made in a simple way from a few planks. “Really whack the mixture into the corners”, Bruno tells us, “Otherwise you might end up with wobbly bricks.” The mould is lifted up and the bricks are left to dry on the ground. To make the next brick it’s important to make the mould wet. The bricks have to dry for 3 days on one side, then they are turned and left to dry for another 3 days. That’s quite a while, but in this climate 6 rain free days is no problem at all.

Bruno shows us how it’s done.

Carefully lifting the mould…

The sun is shining, the kids are playing, the adults are working. It’s a good day: in the end we have made 300 bricks! That might look like an impressive number, but making bricks this way is a very labour intensive process. That’s why places that build this way often call on volunteers to help. But if more and more people transition to natural buildings, will it stay feasible to do it this way? I like pondering questions like these. To explore what will really work if the world transitions to a more sustainable lifestyle. But not now. Now I just know that I’m dead tired, have backache and a sun-burned nose, but feel satisfied and happy and look back on a wonderfully fun day.