Traditional Mud Brick Making and Laying
Ismail Cemal, October 26, 2007
Materials and their collection
Traditional mud brick construction is a cheap and easy form of making all kinds of shelters, either for humans, animals or storage. The energy used to produce the mud brick comes from the sun and manpower. Mud brick has many positive qualities it is load bearing and has good insulation properties. It is also fire resistant and forgiving, meaning that if you make a mistake you can correct it by remaking it. Mud brick construction also has the cleanest ecological footprint as it returns to the earth from where it came. The materials used to make mud bricks are available all over Cyprus. This includes clay soil, chopped straw and water. It is most economical to use readily available materials rather than transport soil in from distant areas. The clay content of soil varies from region to region, as does the colour, which is dependent on minerals such as iron oxide. The colour does not affect the strength of the brick. As there is a lot of farming in Cyprus, local supplies of straw can readily be found. Old straw which is unsuitable for animals is better for mixing and cheaper, if not free. The only other requirements are a wooden mould, a shovel and a wheelbarrow. A mixing trough for the mud is desirable but not necessary.
List of materials and equipment
- Chopped straw
- Wooden Mould(s)
- Mixing trough
The soil has to have 40-60% clay content to be suitable for mud brick making. This can be tested by dissolving soil in water in a clear glass or plastic bottle and letting it settle. In this way the sediment proportions can be observed, as the clay will be settling on the top. As a common rule to find the right type of soil in a village one should ask the locals, particularly the elderly. Most villages have their own local sources of clay soil as transportation was always a problem in the past. If water was found nearby the clay soil source, that was an added advantage for mixing the soil there and making the bricks on location. Once dried the bricks would have to be transported to the building site. Another solution was to bring the soil to the building site and mix and make the bricks there.
In the ancient past the Cyprus mud brick contained no straw. The discovery of adding straw into mud might have been found when the roots of the reeds where the clay soil was quarried was left in the mud and it resulted in a stronger brick. Thereafter, straw of some form has been included in mud bricks.
Going back 60 or 70 years, the straw in the mud brick was obtained from the threshing fields. The threshing of wheat and barley was done by "düven", a board spiked with pieces of flint stone that was pulled over the stalks by oxen. This was followed by "winnowing" which separated the grain from the hay. The finest hay was blown furthest away and this was used as feed for the animals. The larger and heavier straw, mostly the knobs, was closer to where the grain fell. This was called "gondila" and was used mainly in mud brick construction.
In the early 50s the first mechanized threshing machine was introduced, called "Patos". This was driven by a tractor using a flat belt to turn the mechanism. Bundles of wheat or barley would be fed into it and it would separate the grain, gondila and animal hay into three separate piles. The machinery used today threshes the hay that the combine harvester leaves behind in the field. As a result, the straw types are all mixed together. The straw pieces are shorter in length than if done in the old fashioned way. However, to create a longer straw piece which is more suitable to make the mud brick mixture, the speed of the threshing machine can be adjusted down.
Equal amounts of finely chopped straw (which is the animal feed type) and purposely made longer length straw (up to 3 cm) has been found to be the ideal proportion for a better mud mixture than using each on its own. For economic reasons, the finely chopped straw is obtained from shepherds who clean out their storage rooms of old stock as it gets stale and tainted. The stale straw’s outer surface loses its shine and therefore bonds better with clay, so it is an advantage. Wheat produces a better straw for mud brick making than barley. This is because wheat straw has thicker walls, which makes for better tensile strength. Also, the inner surface of the straw (which is exposed on threshing) bonds better with the clay because it is textured.
There are no specifications as to the type of water used in making mud bricks. Sometimes even sea water was used if it was the only water locally available. Seaweed was also used instead of straw in these cases. The salt content does not affect the strength of the mud brick.
At least one but preferably two or three wooden moulds are necessary. The length, width and depth can be variable. The size commonly used in Cyprus is 43cm x 33cm x 7cm. After drying and shrinkage, this brick will measure 42cm x 32cm x 6.5cm. The side measuring 42 cm makes the thickness of the wall. Moulds can be single, double or three-in-one. The inner surface should be smooth for easy release of the mud. The multiple moulds are used by two people and have lifting handles on either end. The single mould has a groove or a protruding edge for easy lifting. Hard timber makes a better mould than a soft wood because they don’t swell when wet or get out of shape. The wood is not painted or varnished.
An ordinary construction wheelbarrow managed by one individual is all that is necessary to carry the mud mixture from the place that it is mixed to where it will be placed in the mould. As new bricks have to stay undisturbed for at least 24 hours, it is most efficient to bring a load of mud to the area where the moulding is being done rather than running back and forth with a shovelful. In olden times, mud was carried to the mould in a stretcher type apparatus carried by two men. It was like a shallow trough, so kept the mixture from falling out.
A square edged shovel is all that is needed. A longer handled one will help to avoid back ache. It is necessary to shovel the mud mix into the wheelbarrow and again into the moulds.
In past times, the mixing trough was created by digging into the ground and pouring water and adding straw. The trough would get bigger and bigger as more soil was used up. In some cases, more soil would be added and worked. Another way of creating a trough was to pile up the dirt then make a pool in the middle of it and fill it with water and let it soak overnight. The next day more water and straw would be added and worked. A concrete based pool with brick walls (50cm high) can be built to carry out the mixing. There are several advantages to this. There is no water loss through absorption in the ground and the mix can last longer without drying out. A pool built for making bricks for one house project could measure 4m X 4m X50cm. This is sufficient volume of mud to make about 300 bricks. The 50cm maximum height is to allow workers to easily step in to mix the mud. The brick pool can be demolished after the project is finished.
Making Mud Bricks
The clay soil is placed into the pool ¾ full, keeping track of the amount in volume. This soil is soaked with water overnight. The next day more water is added and a proportional amount of straw is added gradually as it is worked. The proportions of clay and straw are eight to five. This may vary according to the clay content of the soil. Higher clay content would require more straw.
Working is done by walking in the pool with bare feet which forces the straw to mix with the clay. Rubber boots are not satisfactory as they get sucked off the feet. The water ratio is adjusted by keeping the mix workable. Experience will guide one to create the right mix. The best mix is one that is easy to place in the mould, to remove the mould from and doesn’t lose its shape or crack while drying. Too runny or too hard of a mix are impossible to work with. A good mix doesn’t stick to the shovel. In olden times, the quality of a mix was judged by the way it squished out between the toes while mixing. In conclusion, the best way to learn about the amount of water is by trial and error.
The clay is worked in the mould by hand, using fingers to push the clay mix into the corners and the palm is used to flatten the top. The mould is removed by pulling upwards and the fresh brick is left to dry. The mould is wet to start with and then dipped in water again before making another brick. A small handful of chopped stray is sprinkled where the mould sits to avoid the brick sticking to the soil below. Once they are firm and can be handled, about 24 hours, the mud bricks are stacked in an A-frame position for drying as the underside will dry more evenly too. During the summer months, five days is sufficient to completely dry the bricks then they can be stacked elsewhere or used to start building.
Laying Mud Bricks
Mud bricks are most commonly laid in the stretcher bond, like any other brick (two over one over two etc.), with one difference which is, the length of the brick becomes the width of the wall. This makes it necessary to produce half a brick along the width to bond a course. This half brick should measure 42cm x by 16cm x 6.5cm.
The mortar to lay the bricks is the same mud mixture as is used to make the brick itself. The water ratio is increased to achieve a better workability for spreading it between the courses. This also aides better bonding of the bricks together. The mud brick construction usually has continuous footings which are about 50cm high from ground level. In the traditional method they are built of stone using the mud brick mortar for bonding. The footing serves as a damp proof course and avoids the erosion of the footing by running water.
The mud brick wall surface internally and externally can be finished using different methods and materials. Traditionally, the internal surface was finished by a thin application of gypsum applied by hand and rubbed with a cloth bundled up in the palm. To increase the bonding of the gypsum to the wall surface, the joints are not filled completely while laying the bricks, leaving hollow channels for the gypsum to grip onto. Externally, a thin layer of mud brick mortar is applied by hand. The wall surface is dampened for better bonding and the hollows between the courses act as gripping points for the mortar. Seasonal maintenance of the external wall is necessary to repair wind and rain erosion, usually done in the summer.
Traditional Roof Construction
Ismail Cemal, October 16, 2007
Materials and their collection
Traditionally, the materials used in roof construction in Cyprus depended on what was locally available in the area, for free or at low cost. Transportation in the past was difficult, involving mainly animal power. Also, if one didn’t have a supply of materials, they had to be bought. Building materials on public land were available for a fee to the authorities or alternatively one could buy from private individuals. In the Karpaz, juniper trees were used for roof beams, while in other areas cypress was more commonly used. On top of the beams, cane was placed to support the earth fill. If cane was not available, splintered juniper wood was used instead. In some cases, “wild cane”, which is much thinner, was used, and the beams were placed closer together to compensate for the lack of tensile strength in the cane.
Basic roofing materials for the reconstruction of the roof in Büyükkonuk
The basic materials for the traditional roof reconstruction are:
- Juniper beams
- Saddler’s grass (Semerci otu)
- Adobe (mud-straw mix)
- Cap stones
- Earth fill
- Rain spout
Juniper forests once covered large parts of Cyprus but little remains of them except in the Karpaz. They are very slow growing with a dense, aromatic wood, and a tree measuring 50 cm around could be 100 years old or more. The resin of the juniper acts as a natural deterrent to insect infestation, and, provided they were not lying wet on the ground, cut juniper logs could last for a hundred years or more in the dry interior of a house. They have an excellent tensile strength which enables them to bear the load of the earth fill. The beams we used are, as much as possible, the same ones from the original roof. However, some developed rot on the ends where they have been exposed to the elements and others were damaged when part of the roof collapsed. For these damaged beams, therefore, similar replacement logs were found from other ruins of the corresponding time period. It is estimated that the average age of the trees that were felled for this roof was 75 years and the building was probably constructed 80 years ago. Their average length is three metres and average diameter is 10cm. This is a comparatively good length and size for a juniper beam. The building length internally is 7.6 m and the width is 5.4m. The presence of an arch allows for such a wide room to be created using these three metre beams. They are placed about 33 cm apart, with the thin and thick end positioned alternating. The same principle applies when the ends meet on the arch. The flat cap stones creating the eaves on this adobe building were pieces of medium density limestone rock and were mostly broken when part of the roof caved-in or were damaged in removal as they were in a fragile state. For purposes of creating a longer lasting cap stone, we manufactured them on site, using a white and grey cement mix, stone quarry sand and fine aggregate. Sixty “cap stones” were created from a mould in this manner. An additional drip groove was added to the moulded cap stone to prevent water running down the wall. Although the roof beams are mostly straight, some have forks in them and others slight curvatures and bends. In placing each beam in position, these natural variations have to be considered to create the flattest possible surface where the cane can have maximum contact with each beam below. Once a decision is made on the arrangement of the beams, small stone wedges, gypsum and a mud-straw mix will be used to lock them in position. It is not advisable to have any of the juniper logs hanging out past the external wall as exposure to the elements will reduce its longevity. In some cases where beams were left protruding, the ends were soaked in olive oil to reduce the erosion.
Cane grows in wet areas, such as the base of valleys or as wind breaks bordering citrus groves. The best time of the year to cut cane is February or March, because it is dormant and won’t shrink or be vulnerable to insect infestation. Cutting is done by using large pruning shears or a small axe. Only mature cane, two years old, should be used. After cutting, the cane is dried flat on the ground for the period of a month. This drying makes it ready for cleaning, if the cane is cleaned whilst fresh then insects can penetrate the bud and infestation occurs.
The cane is cleaned with a large kitchen knife starting from the top going to the base with frequent hacking movements of the knife held flat against the cane. This removes the dried leaves from each ‘nub’ or joint along the cane. Once cleaned, the cane is bundled and stored in a dry place.
When the platform of the roof beams has been created, a team of workers line up across the beams to begin tying the cane. Each worker takes a cane called a ‘leader’ which is placed parallel to the beams from the external wall to the arch. These leaders are about a metre apart. Two additional workers are necessary to feed the canes to the tying workers. The feeders give the canes to the top of the line of work across the leaders so that the thick and thin ends of the cane alternate each time. The workers, using twine, tie the cane to the leaders, progressing to the centre of the room, which is the hip of the roof and the top of the arch. As they work they create a strong platform which they can sit and walk on.
This grass grows in large clumps on the sides of the roads and on barren land all around the island. It used to be the stuffing material for donkey saddles, from where it got its name. It is harvested with a sickle or a sharp axe and bundled up and left to dry on the ground. When the cane platform is tied onto the beams, the bundles of saddler’s grass are opened and spread crossways over the cane. In other words, the grass is at right angle to the beams, not parallel. It has to be laid dense enough to create a protective layer between the cane and the mud which will go on top.
Mud and straw mix
This mix is the same material as used in the formation of adobe bricks; soil and straw. The clay content of the soil used is 40 to 60 per cent. Chopped straw is mixed in equal proportions with the soil by volume. It is applied on top of the grass in 5 cm thickness and is usually left to dry before the earth fill is added.
The traditional cap stones are cut out of medium dense limestone rock. The size is usually 50 x 50 cm and the thickness is about 10 cm. There is a hump at one end of the stone which helps to stop the earth fill from falling off the edge. It also counter balances the cap stone at the edge of the wall and also creates a guide for the runoff. They overhang the wall about 20 cm. Their purpose is to protect the wall from water erosion from rainwater running off the roof. The cap stones accommodate and provide support for the rain spouts. In some cases, the rain spout is actually carved into the cap stone itself and it protrudes further from the edge line of the other cap stones.
Earth fill is of the same soil that is used in making adobe bricks and the mud layer on top of the grass. In this case it is applied dry and there is no straw mixed in it. The purpose of the earth fill is to create the right angle desired on the roof to disperse the water successfully, so it doesn’t collect or run too quickly so as to create an erosion gully. The earth fill is usually 10 cm thick and is rolled with a stone roller to compact it. In our case, we are going to place a concrete layer on top of this earth fill. However, traditionally, before concrete was available, there was another thin layer of rich clay placed on top of this earth fill. It was rolled in a similar manner and had to be maintained every year before the winter. After a period of time, when it was felt that the layer of earth and mud was too thick and therefore too heavy for the timber beams to support, layers of fill were scraped back and removed and replaced with a new top layer of rich clay.
The use of concrete on top of the roof came into practice after the Second World War. A thin layer of concrete, about 5 cm thick, was placed on top of the earth fill to replace the thin layer of rich clay. It required less maintenance because it was less likely to be eroded by the weather and plants couldn’t grow on it. It was formed to accommodate some rain spouts and the hump of the cap stones acted as a guide to divert the water into the spouts and off the roof. The concrete roof served the villagers as a space to dry crops such as sesame, olives, wheat, raisins, etc. It was also commonly used in the hot summer nights for sleeping.
These spouts were made of terracotta, about 40 cm long with a diameter of 8 cm on one end and 5 cm at the overhanging end. They were mounted in concrete and water from the roof was diverted towards them. Before concrete, they were held in position with a few stones stacked up on top of them. Later on, galvanized metal pipes and much later, PVC pipes were also used for rain spouts.