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//-->BUILDING WITHSTONE AND EARTHPART IIIn part one Richard Tufnell explained how to build a rondavel out of stone. In thissecond part he demonstrates the same techniques on a square building, anddescribes an alternative 'single skin' wall.You know from Part I how tobuild a round rondavel; it is eveneasier to build a 'squarerondavel'. The only difference inthe equipment is that you willneed four straight poles and fourshort pegs (or more poles) to usefor measuring, instead of one.Decide what size you want yoursquare rondavel to be, and placea long pole upright on theoutside of each comer. Attachstrings right round the square,about one hands' width off theground. Then hammer in a shortpeg on the inside of each comer,leaving a space the desiredwidth of the wall, and connectthese up with string in the sameway (below).Figure 1: Marking out for a square buildingJust as with the round rondavel,you must lay a foundation layer of stone without using mud. This is done by laying the stonesso that each one sticks out from under the string by about three fingers' width. When youcome to a comer pole, lay the stones beside it.When the foundation is finished, you will have what looks like a stone path a little bit widerthan the strings, all the way round.Next, raise the strings up the poles all the wayround by perhaps a hand's width or a little bitmore. These strings are now used to guide youas you build the wall. Mix the mud mortar asbefore, and begin building your wall just asdescribed for round buildings.Of course, square rondavels have corners,which round ones do not. For these, try andfind stones that are a little larger and longerthan the average. These are then laid so thatthe long side of the first stone goes along onewall, and the long side of the stone on the nextrow up goes along the other wall. This ties thewalls together well and makes for a strongfinish. Look at the figure below to see how thisworks.Figure 2: Use longer stones to tie thecorners together.Because the strings are fixed to the poles, all you have to do to keep your wall straight is toBuilding with stone & earth: Part IIPractical Actionmake sure that each stone is laid so that it almosttouches the string. There has to be a very tiny gapbetween the stone andSafetythe string. If the stoneBuilding with stone and earthdoes touch the stringis not dangerous, but thereany-where, it will pushare one or two points thatthe string outwards, soyou should bear in mind.that when you lay theDo not try to lift a stone thatnext layer of stonesis too heavy. Get some onethey will be in theelse to help you.wrong position. Usingthe strings as anIf you have to break stone toaccurate guide isget the sizes and shapesextremely important; ifthat you need, rememberyou do it correctly,that sharp pieces of stoneyour rondavel will lookcan fly off at high speed. It isvery good indeed andvery important to protectbe very stable.your eyes, so close yourWhen you reach thedoor poles you buildFigure 3:Building up to the doorthe same way as youpolesdid for the roundrondavel. Try to use a long stone that extends the wholewidth of the wall, and then balance it with two stones on the next layer.Every time you have built up to the strings, raise them again by about a hand's width, andcontinue until the wall is the height you want. Remember to brush the joints smooth withwater once the mud is about half dry.eyes at the moment ofimpact, hold your other armup to shield your eyes or,best of all, wear protectiveglasses or a mask.Single wallsThe examples given here have used walls with two'skins' –one inside and one outside, with the middlefilled with mud and waste stone. These are usuallyknown as 'double’ walls. If you are fortunateenough to have enough of the right size of stone,or you are prepared to search for longer in order tofind stones that are suitable, then there is a methodof using mud and stone that is even easier andquicker to build. This is known as single, or 'singleskin' walling.You will need a good number of building stonesthat are not less than about 30cm long, and theflatter and more regular they are, the easier it willbe to build with them. It should be noted that usingthis method will give a strong house or otherbuilding of one storey, but it is not suitable for tallerstructures.For your foundation layer, you will need enoughstones that are even longer than 30cm, so that thefoundation layer is wider than the wall itself.Figure 4: The foundation layer iswider than the wallMarking OutFor a round rondavel, you will need at this stage a central pole but for a square rondavel youwill only need the four long outside poles described earlier, not the inner pegs, when youbuild a 'single' wall.2Building with stone & earth: Part IIPractical ActionLet us assume that you are building a round rondavel, and that you have carefully placed astraight pole in the centre. Mark out the size of the building on the ground as described in theprevious article, using a string and peg, except that you will only need to mark one circle onthe ground, not two. This circle will mark the outside of the foundation course. Next lay asingle layer of large stones, 35-40cm long, as the foundation course. Each stone is placedagainst the rim of the circle you have drawn on the ground, with the stone inside the circle.Ensure that they are all touching each other and are pinned securely so that there is nomovement when they are tested by being walked on. If any of the stones do move, securethem by putting small wedge-shaped pieces of stone underneath, until the foundation stone isstable After this, tie a marker knot in the string about 4 to 6cm in from the outside of thefoundation circle to guide you as you build.Place a thin layer of mudon an area of thefoundation stones andplace building stones onthe mud one by one,breaking the joints byplacing each stone so thatit covers a joint of thestones in the layer below.Use the guide knot on thestring to measure theoutside face of the stonesonly. The stones will eachbe a slightly differentlength, so the outside willhave a smooth face, andthe face on the inside ofthe rondavel will beFigure 5: Only one circle is needed for a single skin wallslightly irregular. (You canalways plaster the insideafterwards if you wish.)Remember to use only enough mud to sit the stones securely. Do not use thick layers. If partof the stone you are laying touches through the mud onto the stone below, so much thebetter.When you come to the doorway, try to alternate long stones with shorter ones, so that thedoor opening is tied well into the wall.You can build this type of building in only three or four days if you have the right materials.But you do not often get something for nothing, and a fast building time is usually balancedby the extra time it takes to find the right type of stones. On the other hand, you will needmuch less stone overall for a single skin wall than for a double.Finishing the wallHow you finish your wall when it is built is entirely up to you. Some people like to plaster theinside to make sure there are no places for insects to hide, although if you have brushed thejoints smooth, this should not be necessary. Others like to plaster both sides. This can bedone with either pure mud mortar (remember to wet the walls to help the plaster stick if this isdone after the wall is completely dry) or with a plaster made with cement. Cement-basedplaster does help prevent minor damage in the rains, but if it is difficult for you to get supplies,do not worry; your building will still be good and strong.If the outside is plastered, some people paint their rondavel a single colour, and thendecorate it with a simple design. In parts of Africa, some family groups are known by thedifferent pictures each one uses. Painting the rondavels white helps keep them cool in the hot3Building with stone & earth: Part IIPractical Actionseason, and makes them look very smart and cheerful.Maintaining your buildingYour building will last very many years -almost certainly much longer than you! There shouldbe very little need for any maintenance or repairs, provided you have made built a roof whichhangs over the walls as much as possible, as explained in the previous article. You may needto mix up a little bit of mud mortar and press it in between the stones after the rainy season,but it is unlikely. The roof will probably need more regular maintenance than the building.Useful AddressesbasinWebsite:http://www.gtz.de/basinbasinis the Building Advisory Service and Information Network.This technical brief was originally written by Richard Tufnell of Dry Stone MasonryConservancy, Kentucky, USA and the illustrated by Bill Holmes for theAppropriateTechnologymagazine Volume 24/Number 3 Dec 1997.For more information aboutAppropriate Technologycontact:Research Information Ltd.222 Maylands AvenueHemel Hempstead, Herts.HP2 7TDUnited KingdomTel: +44 (0)20 8328 2470Fax: +44 (0)1442 259395E-mail:info@researchinformation.co.ukWebsite:http://www.researchinformation.co.uk http://www.apprpriatechnology.com4 [ Pobierz całość w formacie PDF ]
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//-->BUILDING WITHSTONE AND EARTHPART IIIn part one Richard Tufnell explained how to build a rondavel out of stone. In thissecond part he demonstrates the same techniques on a square building, anddescribes an alternative 'single skin' wall.You know from Part I how tobuild a round rondavel; it is eveneasier to build a 'squarerondavel'. The only difference inthe equipment is that you willneed four straight poles and fourshort pegs (or more poles) to usefor measuring, instead of one.Decide what size you want yoursquare rondavel to be, and placea long pole upright on theoutside of each comer. Attachstrings right round the square,about one hands' width off theground. Then hammer in a shortpeg on the inside of each comer,leaving a space the desiredwidth of the wall, and connectthese up with string in the sameway (below).Figure 1: Marking out for a square buildingJust as with the round rondavel,you must lay a foundation layer of stone without using mud. This is done by laying the stonesso that each one sticks out from under the string by about three fingers' width. When youcome to a comer pole, lay the stones beside it.When the foundation is finished, you will have what looks like a stone path a little bit widerthan the strings, all the way round.Next, raise the strings up the poles all the wayround by perhaps a hand's width or a little bitmore. These strings are now used to guide youas you build the wall. Mix the mud mortar asbefore, and begin building your wall just asdescribed for round buildings.Of course, square rondavels have corners,which round ones do not. For these, try andfind stones that are a little larger and longerthan the average. These are then laid so thatthe long side of the first stone goes along onewall, and the long side of the stone on the nextrow up goes along the other wall. This ties thewalls together well and makes for a strongfinish. Look at the figure below to see how thisworks.Figure 2: Use longer stones to tie thecorners together.Because the strings are fixed to the poles, all you have to do to keep your wall straight is toBuilding with stone & earth: Part IIPractical Actionmake sure that each stone is laid so that it almosttouches the string. There has to be a very tiny gapbetween the stone andSafetythe string. If the stoneBuilding with stone and earthdoes touch the stringis not dangerous, but thereany-where, it will pushare one or two points thatthe string outwards, soyou should bear in mind.that when you lay theDo not try to lift a stone thatnext layer of stonesis too heavy. Get some onethey will be in theelse to help you.wrong position. Usingthe strings as anIf you have to break stone toaccurate guide isget the sizes and shapesextremely important; ifthat you need, rememberyou do it correctly,that sharp pieces of stoneyour rondavel will lookcan fly off at high speed. It isvery good indeed andvery important to protectbe very stable.your eyes, so close yourWhen you reach thedoor poles you buildFigure 3:Building up to the doorthe same way as youpolesdid for the roundrondavel. Try to use a long stone that extends the wholewidth of the wall, and then balance it with two stones on the next layer.Every time you have built up to the strings, raise them again by about a hand's width, andcontinue until the wall is the height you want. Remember to brush the joints smooth withwater once the mud is about half dry.eyes at the moment ofimpact, hold your other armup to shield your eyes or,best of all, wear protectiveglasses or a mask.Single wallsThe examples given here have used walls with two'skins' –one inside and one outside, with the middlefilled with mud and waste stone. These are usuallyknown as 'double’ walls. If you are fortunateenough to have enough of the right size of stone,or you are prepared to search for longer in order tofind stones that are suitable, then there is a methodof using mud and stone that is even easier andquicker to build. This is known as single, or 'singleskin' walling.You will need a good number of building stonesthat are not less than about 30cm long, and theflatter and more regular they are, the easier it willbe to build with them. It should be noted that usingthis method will give a strong house or otherbuilding of one storey, but it is not suitable for tallerstructures.For your foundation layer, you will need enoughstones that are even longer than 30cm, so that thefoundation layer is wider than the wall itself.Figure 4: The foundation layer iswider than the wallMarking OutFor a round rondavel, you will need at this stage a central pole but for a square rondavel youwill only need the four long outside poles described earlier, not the inner pegs, when youbuild a 'single' wall.2Building with stone & earth: Part IIPractical ActionLet us assume that you are building a round rondavel, and that you have carefully placed astraight pole in the centre. Mark out the size of the building on the ground as described in theprevious article, using a string and peg, except that you will only need to mark one circle onthe ground, not two. This circle will mark the outside of the foundation course. Next lay asingle layer of large stones, 35-40cm long, as the foundation course. Each stone is placedagainst the rim of the circle you have drawn on the ground, with the stone inside the circle.Ensure that they are all touching each other and are pinned securely so that there is nomovement when they are tested by being walked on. If any of the stones do move, securethem by putting small wedge-shaped pieces of stone underneath, until the foundation stone isstable After this, tie a marker knot in the string about 4 to 6cm in from the outside of thefoundation circle to guide you as you build.Place a thin layer of mudon an area of thefoundation stones andplace building stones onthe mud one by one,breaking the joints byplacing each stone so thatit covers a joint of thestones in the layer below.Use the guide knot on thestring to measure theoutside face of the stonesonly. The stones will eachbe a slightly differentlength, so the outside willhave a smooth face, andthe face on the inside ofthe rondavel will beFigure 5: Only one circle is needed for a single skin wallslightly irregular. (You canalways plaster the insideafterwards if you wish.)Remember to use only enough mud to sit the stones securely. Do not use thick layers. If partof the stone you are laying touches through the mud onto the stone below, so much thebetter.When you come to the doorway, try to alternate long stones with shorter ones, so that thedoor opening is tied well into the wall.You can build this type of building in only three or four days if you have the right materials.But you do not often get something for nothing, and a fast building time is usually balancedby the extra time it takes to find the right type of stones. On the other hand, you will needmuch less stone overall for a single skin wall than for a double.Finishing the wallHow you finish your wall when it is built is entirely up to you. Some people like to plaster theinside to make sure there are no places for insects to hide, although if you have brushed thejoints smooth, this should not be necessary. Others like to plaster both sides. This can bedone with either pure mud mortar (remember to wet the walls to help the plaster stick if this isdone after the wall is completely dry) or with a plaster made with cement. Cement-basedplaster does help prevent minor damage in the rains, but if it is difficult for you to get supplies,do not worry; your building will still be good and strong.If the outside is plastered, some people paint their rondavel a single colour, and thendecorate it with a simple design. In parts of Africa, some family groups are known by thedifferent pictures each one uses. Painting the rondavels white helps keep them cool in the hot3Building with stone & earth: Part IIPractical Actionseason, and makes them look very smart and cheerful.Maintaining your buildingYour building will last very many years -almost certainly much longer than you! There shouldbe very little need for any maintenance or repairs, provided you have made built a roof whichhangs over the walls as much as possible, as explained in the previous article. You may needto mix up a little bit of mud mortar and press it in between the stones after the rainy season,but it is unlikely. The roof will probably need more regular maintenance than the building.Useful AddressesbasinWebsite:http://www.gtz.de/basinbasinis the Building Advisory Service and Information Network.This technical brief was originally written by Richard Tufnell of Dry Stone MasonryConservancy, Kentucky, USA and the illustrated by Bill Holmes for theAppropriateTechnologymagazine Volume 24/Number 3 Dec 1997.For more information aboutAppropriate Technologycontact:Research Information Ltd.222 Maylands AvenueHemel Hempstead, Herts.HP2 7TDUnited KingdomTel: +44 (0)20 8328 2470Fax: +44 (0)1442 259395E-mail:info@researchinformation.co.ukWebsite:http://www.researchinformation.co.uk http://www.apprpriatechnology.com4 [ Pobierz całość w formacie PDF ]