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Cas Houses, Siirt's Distinctive Building Language

Walking through the old neighbourhoods of Siirt, the first thing you notice is the posture of the houses. The walls are stone, and the surface is covered with a gypsum-based plaster.

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Cas Houses, Siirt's Distinctive Building Language

Walking through the old neighbourhoods of Siirt, the first thing you notice is the posture of the houses. The walls are stone, and the surface is covered with a gypsum-based plaster. The windows are small, the doors are heavy, and the roofs look flat. Locals call these buildings cas houses, and they take their name from the material that holds them up. Cas houses are not a single monument but a building tradition. This article introduces that tradition, from its material and climate to its courtyards and street fabric, and explains where and how you can see it today.

What cas is and how it is made

According to the definition on the Culture Portal, cas is a kind of coarse plaster obtained by burning gypsum stone from around Siirt in kilns and then grinding it. In other words, cas is a building material that comes out of the city's own soil. The article by researchers from Atatürk University describes the process in more detail. A mixture is prepared from gypsum stone and rubble from the surroundings, piled in a pyramid shape so that it dries, packed with fuel such as wood, and fired for about three days. The dried material turns into lumps. The lumps are then crushed with a mallet until they become a powder.

In the hands of the masons, the finished powder is combined with pieces of cut stone and rubble. According to the article, with this method the masons can raise a two or three storey house with a domed ceiling in a short time, somewhere between fifteen and twenty days. Quick setting is the most important property of cas mortar. The same property made it easy to enlarge houses over time by adding new rooms or floors.

Geography and water

To understand why cas houses appeared here, it helps to look at the map. According to the article, Siirt lies on the southern foothills of the Southeastern Taurus mountains. Both Siirt and Batman hold important gypsum deposits. Besides these deposits, rocks such as limestone, sandstone and marl also supply building material. The raw material, in short, lies right beside the houses.

The Botan River, which flows through the province, is one of the most important tributaries of the Tigris. Its valley is generally narrow, and the land that can be farmed or settled is quite limited. The fact that Siirt sits in an important catchment area of the Tigris also shaped how the houses were set up. According to the article, the courtyard of a cas house usually holds a water well, so the family can make use of the water around it. When stone, gypsum and water meet in the same narrow valley, this distinctive building language is the result.

Wall, dome and small window

The Culture Portal writes that these houses are built of rubble, fieldstone and cut stone. The walls are quite thick, and the covering above is just as heavy. The houses usually have two or three storeys. From outside the roof looks flat, but from inside the ceilings of the rooms are shaped like domes. The researchers describe this design as a method that is not common in our country and regard it as a solution for keeping heat inside.

On the facade, small rectangular windows with arched tops catch the eye. Some houses have a projecting balcony, and in the words of the article this gives the building the look of a small fortress. The heavy, closed appearance that stone and plaster give strengthens that impression. When you look with your own eyes, pay attention to the size of the windows and the shape of the arch. Behind the small opening lies a calculation about climate.

Do not forget the small skylight windows opened into the roof level either. The article writes that windows of this kind were opened in the roof sections to make the most of daylight. The small wooden-framed windows, mostly with round arches at the top, add a further charm to the houses.

A house designed together with the climate

Summers in Siirt are hot and dry, and winters are cool and rainy. According to the observation data given in the article, the average highest temperature in July is 37.1 degrees, and the average lowest temperature in December is minus 8.8 degrees. A house must be able to withstand this range. The Culture Portal states that the walls are built to keep out the heat in summer and the cold in winter, and that the pyramid shape was chosen to suit the climate.

The same source stresses that these houses are made of natural materials that do not harm the environment. According to the article, the insulating role of the mortar keeps the houses cool in summer and warm in winter. The pyramid-shaped covering and the window size are also part of this equation. A cas house, then, is a building designed for living, not for decoration. Looking at these old houses is instructive today, when energy efficiency is so often discussed.

From the door to the courtyard, from the courtyard to the room

The article also describes the interior layout in detail. The house is entered through an ornate double-leaf door. Two knockers hang on the door. The one shaped like a fist makes a dull sound, and the one shaped like an open hand makes a sharp sound. This way the household can tell from the sound of the knocker whether a woman or a man is at the door. The door also has a small peephole.

Behind the door stretches a courtyard surrounded by high walls. Known locally as havş, it is where the daily work of the family takes place. According to the article, it holds a water well, a mortar called dibek used to grind wheat and bulgur, and a place set aside for winter firewood. A room called mahsara, where dried foods such as pestil and köme are prepared, is also in the courtyard. In summer the courtyard can be covered with planks to make room for grapevines.

Passing through the courtyard, you reach the room called behu, where guests are received. According to the article, this room is cool in summer and warm in winter. The tabok, reached by a few steps down beside the behu, is a kind of cellar used to store perishable winter foods such as cheese and meat. The çırtak is a section used like a balcony. The kabbele, built into the wall, is a storage space for quilts and pillows, similar to what we would now call a niche. The number of rooms varies with the size and structure of the family.

Street fabric and abbares

Cas houses live not one by one but as a whole, street by street. The article writes that these houses are sometimes linked by successive arches, with roads passing beneath them. The section above these passages, called abbare locally, is part of the house and is used as living space. According to the article, the passages protect houses from damp and help the circulation of air in the street. They usually carry the surname or nickname of the family living above.

Where to see them today

According to the article, in Siirt Merkez the cas houses are concentrated in the Ülkü, Tınaztepe, Conkbayırı, Sakarya and İnönü neighbourhoods. In Tınaztepe and Ülkü, the old founding area of the city, they are found scattered. In Tillo, by contrast, they spread across the whole district centre. The article links this to the plainer terrain of Tillo compared with the central district and to the importance local people attach to protecting these works. Tillo, formerly called Aydınlar, lies about 7 kilometres northeast of the centre of Siirt according to Sönmez's study. The same study counts the historic Tillo cas houses among the main cultural attractions of the district.

These houses are still used as homes. For that reason you should keep quiet at doorsteps, never enter a courtyard without permission, and show respect to residents when taking photographs. The location information on the official page gives a street address, but not every house is open to visitors. When planning a trip it is wise to ask the Siirt Provincial Directorate of Culture and Tourism and the Culture Portal for current information.

The difficulty of protection

The future of cas houses is not easy. The article notes that these houses have lost their original form through later additions of fired brick, concrete block or reinforced concrete. The authors say that building a cas house is costly and the craft is hard, that the spread of cement and cheaper modern plasters has made people forget cas mortar, and that the number of masters is falling. They add that the iron profiles used in repairs harm the historic and architectural fabric of the houses.

So when you look at cas houses, do not see only a handsome facade. Each is one of the last examples of knowledge built with local material, for the local climate and for local life. The researchers argue that these houses should be seen as cultural heritage, protected and made use of for tourism.

Practical tips for your walk

For photographs choose the morning or the late afternoon. In side light the texture of stone and plaster looks more distinct. Close-ups of the arched windows and door knockers are rewarding, but ask for permission first. The streets can be narrow and the ground uneven, so wear comfortable shoes. Keep away from damaged walls, extensions that risk collapse, and neglected buildings.

If you walk in summer heat, avoid the midday hours and carry water. In rainy weather remember that the ground in narrow streets can become slippery. According to Sönmez's study, the Tillo area also has terrain suitable for paragliding and rafting. Ask the authorised organisations for information about these activities.

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