Ecological Design Blog

Building a proper drainage

10/19/2015

Our government and individual citizens spend billions of dollars managing stormwater, and for good reason, water is powerful and can quickly cause serious property damage when cities and structures are not properly designed for big precipitation events. Luckily you have the power to mange stormwater on your own property. Following the design principles of permaculture you can be sure that stormwater doesn't cause any damage, and you can even use it to your advantage, by harvesting it.

In a future blog we will discuss the intricacies of designing stormwater management systems and how to harvest the water, but for this blog we want to show you just one design element that can be used in many situations.

This example will show the construction of a drainage system on the uphill side of the cob house we are currently constructing. We bury rocks that are wrapped inside a blanket of landscape cloth to facilitate drainage away from the house.

Pictures are in sequence, from beginning to end.

We built a small rock wall to serve as the support (stem wall) for our cob walls.

We lay down landscape cloth. The left side of the cloth is already set up as a drainage with pipe and rocks that leads away from the house.

Put about 6-8 inches of medium sized roundish rocks onto the middle of the cloth. Be careful rocks aren't sharp or they can puncture the cloth.

Wrap rocks like a burrito. Put a little soil on it to hold closed.

Cover up with soil. We used decomposed granite so when the ground is wet around the house it will be easy to walk on.

Pause to watch the sunset.

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Brief history of cob and earthen construction

10/12/2015

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So, cob is comprised of clay, sand and straw. That's it! These materials are ridiculously cheap and easy to come by almost anywhere on the planet. When properly mixed together they become incredibly strong, durable and beautiful - the perfect combination for a home. Cob ingredients are mixed in the proper ratio, then stacked in layers or sculpted by hand into the forms of walls, etc. Similarly, adobe bricks contain the same materials but they are dried in brick form, then used to make a structure.

The beginnings of a cob structure.

To the best of our current knowledge, cob and adobe type materials have been used for well over 10,000 years. Throughout time the art of natural building evolved into forms such as sod, rammed earth, straw-clay, wattle-and-daub, etc. Cob is an English term for mud building in which no forms nor wooden structures are used in the building process. In Old English "cob" means loaf. Similar forms of earthen building are found throughout Europe, the Middle East, Africa, Asia and the US.

A cob home in the UK. Built in around the 1400s. Credit telegraph.co.uk

The Great Wall of China, built about 2,000 years ago, was mostly built of earthen bricks. Some of the massive pyramids in Egypt were built with earthen materials. These are some of the largest structures on earth.

It is estimated that close to 50% of people on this planet live in earthen buildings, like cob.

This image shows a city in Yemen made entirely of cob! It's huge and you can see buildings that are quite a few stories high. This really exemplifies cob's structural strength. The outside of the buildings are finished with a lime plaster.

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Building a proper drainage

Brief history of cob and earthen construction

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