[Cob] Cob roofing in Malta

[Kathryn Marsh]

Just back from Malta where I was fascinated by the the ancient cob flat roofs which are used to collect water. The island has no natural water and is entirely dependent on a combination of small natural underground lakes, which collect what seeps through the limestone rock, and cisterns carved out under the houses. Many of these cisterns are hundreds of years old and the water for them is collected from these flat roofs. Nowadays they are membrane lined but I saw many, including one on my friend's house, that are made of cob. A mixture of clay and very fine limestone pebbles is pounded with wooden mallets until it is completely plastic and smooth and then simply left to dry. When the roof develops leaks another layer is added. I saw some that were up to fifteen inches thick. The houses are built of limestone, including the roofs which are made of long limestone blocks known as xorocs, with corbelled supports, and the cob bowl that collects the water is built up on top of them, draining down to a channel that leads into limestone down pipes that feed into the cisterns under the houses. Building up the cob surface is regarded as women's work but I couldn't find any young women who had ever learned how to do it or were interested in learning. I did meet a couple of very aged women who saw it as being as normal a part of house maintenance as painting the shutters

kathryn