Build a doghouse with earth_Part1: Plan and Foundation
Updated: Dec 21, 2020
Since I’ve learnt earthen architecture, I’ve wanted to build a doghouse for one of my dogs. My family has three dogs, and two of them are very furry. Since they are really struggling to survive in the hot and humid summer in South Korea, I have wanted to build a rammed earth house for one of them. Rammed earth is an outstanding thermal mass, so it serves to maintain consistent indoor temperature and humidity from fluctuating outdoor climate.
Since the closure of my university from March, I have come back to Korea and kept thinking initiating the doghouse project. However, due to a two-month heavy rain season (very unusual, it was caused by climate change) and typhoons, my project has been delayed and finally started from the end of August. A preparation process took a long time than I expected.
The first step I did before planning was an environmental analysis. Since earthen architecture is eroded or affected by rainfalls, therefore, the analysis of prevailing wind directions is fundamental to determine the direction of opening and the appropriate use of stabiliser or impervious materials. Based on the wind analysis of the site, it turned out that the strength and frequency of wind is weak from the south, and this perfectly matches with the movement of the sun in South Korea. The sun rises high in the summer while low in the winter. Therefore, if opening is open towards the south, the doghouse will get minimum sunlight in the summer, but maximum sunlight in the winter, while getting minimum rainfalls coming from the opening.
At the next step, I planned the doghouse’s floor plan and section. Initially, I designed a slanting roof, but I am currently considering building an arch for structural stability and the minimised use of steels and waterproofing materials. The design of the roof is still on process.
When it comes to the construction of foundation, I used poured earth. Poured earth follows a same construction process like concrete, so it has a plasticity, but it uses soils instead of cement. The earthen mixture of poured earth was created with lime (1) : soil (2) : sand (3). The ratio was found that earthen structure achieves a maximum strength based on my earthen construction experience in Korea with the local soil, therefore, the ratio is subject to change at a different site.
I positioned the direction of foundation to face the south (the opening of a doghouse will be also towards the south) and set poles around the site to mark the area of the site. Then, I excavated the depth of about 15cm of soils from the site. (Since the site was already rocky after digging 10cm, it was very hard to dig further.) I rammed hard the excavated ground with a rammer, and laid a plastic sheet and a wire mesh. Cast earth was poured over them, and I rammed every second layer of cast earth to extract moisture and enhance its strength. An extra wire mesh was embedded in the process. The foundation was completed with total 100kg of lime, 200kg of earth, and 300kg of sand.
At the next episode, I will share the fabrication process of fabric formwork for a rammed earth wall.