Another alternative building method is cob building. According to Ianto Evans in The Hand-Sculpted House, 2002, “Cob is a structural composite of earth, water, straw, clay and sand, hand sculpted into buildings while still pliable. There are no forms as in rammed earth, no bricks as in abode, no additives or chemicals and no need for machinery.” This means that organic forms are possible, easy to achieve and creative, beautiful details can be included in the building. The high thermal mass helps temperatures to stay consistent and comfortable and it is compatible with other natural materials such as wood, stone and lime. An added bonus is that it is fun to build with friends. Unfortunately it is a very labour intensive process and also unfamiliar to local municipalities.
The cob mixture consists of approximately 1 part clay, 4 parts sand and 1 part straw. For cob walls you will need a foundation that will keep the walls away from damp ground and for this, stone or reclaimed concrete chunks work well. Once you’ve made your mixture (the best way to do this is with your feet), break it into manageable sized cobs – this name originated from the old English term for ‘lump’. Building your structure is as easy as placing the cobs and smashing them into one another to form a single unit. This is where you can get creative and add detail, from engravings and sculptures in the walls to functional items forming part of the walls, like shelves, fireplaces and bathtubs. The structure is finished with two coats of plaster, a brown coat to even out imperfections and a final coat that can be polished or sealed with linseed or hemp oil.
Figure 1 is a lantern or candle niche and was done by Alexor and Joelle for their house. Have a look at their website, https://cobbedinthemountains.wordpress.com, where they’ve detailed the whole process. Figure 2 shows how creative you can be and everything that can be made using cob. On Kirk Nielsen’s website there are a lot of inspirational images of what can be achieved with cob. (https://www.kirknielsen.com/project/cob/). Figure 3 is of Whispering Hills Cob Cottage.
Figures 4 and 5 are of Elämän Puu cottage in Finland and Figure 6 is Laughing House in Oregon, USA, showing that cob buildings can be organic and sculptural or almost conventional in style.