Kagir tarihi yapılarda nem problemlerinin teşhis ve çözümü

Abstract

Bu çalışmada kagir tarihi yapılarda ortaya çıkan nem problemleri, bunların teşhis ve çözüm yöntemleri tanıtılmaktadır. Bu yöntemlerin derlenip tanıtılmasından ve değerlendirilmesinden oluşan çalışmada amaç kagir sistemli tarihi yapılarda nem problemi ile mücadele sürecini tanıtmak, birbirini izleyen veya eşzamanlı adımlar şeklinde sistematikleştirmek ve genel hatlarla nem problemleri ile mücadele yöntemi geliştirmektir. Bölüm 1 'de yapılan çalışmayla ilgili bilgiler verilerek tarihi mirasın korunması açısından ve diğer bozulma nedenleri arasında nem probleminin önemi vurgulanmaktadır. Bölüm 2'de daha sonraki bölümlerde detaylı olarak açıklanacak olan nemlenme problemlerinin, teşhis ve çözüm aşamalarının kavranabilmesi açısından nemlenme olayının dayandığı hava ve malzeme özellikleri tanımlanmaktadır. Bölüm 3'te araştırma kapsamındaki kagir sistemli tarihi yapılardaki nem problemlerini modern yapılardakinden ayıran başlıca etken olan geleneksel malzemeler, geleneksel yapım tekniği bütünlüğü içinde, kullanımları ve karşılaştıkları bozucu etkenler açısından incelenmektedir. Araştırma kapsamı dışında kalan ahşap ve metal malzemeler birçok kagir yapıda bütünleyici olarak kullanıldığı için kısaca tanıtılmaktadır. Bölüm 4'te genel olarak tarihi yapılarda nem kaynakları olan;. Zemin neminin,. Yağış sularının,. Havadaki nemin etkileri ve bunların alt başlıkları olan nemlenme şekilleri tanıtılmaktadır. Bölüm 5'te nem problemi ile mücadelede gerekli tespitlerin yapılması ve sonucunda elde edilen bulguların değerlendirilmesinden oluşan teşhis aşaması anlatılmaktadır. Bölüm 6'da nem kaynağının kontrolüne, yapıyla ilişkisinin kesilmesine veya belirtilerin gizlenmesine dayanan problemlerinin çözüm yöntemleri incelen mekte, yöntemlerin birbirlerine ve başka kaynaklı nem problemlerine etkileri değerlendirilmektedir. Bölüm 7'de nem problemlerinin çözümüne yönelik müdahalelerin başarısı ve yeterliliğinin kontrolünün gereği belirtilmektedir. Düzenli kontrollerle tespit edilen aksaklıkları gidermeye yönelik geri besleme alt süreci işletilerek kalıcı bir çözüm sağlanmasına yönelik kontrol süreci açıklanmaktadır. Bölüm 8'de alan çalışması olarak nem problemi olan kagir bir yapı incelenmiş, nemlenmenin kaynağı araştırılarak çözüm önerilmiştir. Bu çalışma sonucunda derlenen bilgiler ışığında nemle mücadele sisteminin kurulmasına yardımcı olmaya yönelik bir akış şeması oluşturulmuştur.

in this study the causes of dampness problems of historic buildings and the methods to combat these problems are gathered together and explained in a systematic approach. As a cpnclusion a method is produced which consists of the steps of diagnosing the sources of dampness problems, coming över them and the control process of the solution with feedback steps. This study comprises seven main chapters: in chapter 1, the importance of dampness among other causes of defects and deteriorations which are movement caused by structural loads and biological and chemical attacks, is stated. The sources of dampness and the method to combat them is introduced. in chapter 2, the main definitions of terms, relating to the humidity of air and basic properties of materials about the way they get damp are given. in chapter 3, the main types of historic building materials are described with the way they have been used in the building structure, their characteristics of getting damp ör dry and the defective causes they have been standing. The materials are classified as:. vvoods. metals. masonry materials.. earth based: brick, mud brick and mortars.. stones and though the scope of this study consists of masonry structures also vvoods and metals are described to some extent because of their supplementary usage with masonry. A masonry structure consists of artificial ör natural blocks of certain sizes, mortars and renders that had been used in plastic form with the responsibility of holding the blocks together and protecting them by covering ali över outside and inside as they get hard. At the point of understanding the problems of 'historic buildings' this chapter has special importance, because modern building materials and structures differ a lot with their pore structure and capillaries. Historic building materials generally consist of natural materials ör produced by primitive technics: burning in uncontrolled kilns ör drying in the sun. When the lack of standardization of building technics and the effects of exposure to natural and manmade causes of decay are added to these, the problem of combating the problems of historic buildings becomes much more complicated. xi The presence of water damages the building materials in the follovving vvays:. Softening, because of dissolving of the clayey substances in vvater.. Freezing damage: As the volume of vvater increases when freezes, it applies an expanding force to the pore surfaces. This phenomenon mostly damages the surface materials in the exposure of climatic effects vvhere the temperature alters betvveen wide ranges in a short period. The range of decay is related to the saturation coefficient of the material.. Chemical damage: The vvater from any source dissolves and carries the chemical materials and the minerals of the building materials and accumulates them vvhere it evaporates. This damages the chemical eguilibrium and physical durability of the material and more över the crystallization of salts defects the surface in a short time. If drying is rapid, crystallization occurs behind the surface and causes severe deteriorations. If the source of dampness is ground vvater the salts of the ground are also carried through the building materials and accumuiated near the evaporating place. VVater carries the pollutants of the air to the surface of the building fabric and serves as a media for the reaction betvveen the building material and the pollutants called aerosols. The extent of the damage depends on the kinds and amounts of chemicals, the amount of vvater and the kind of building material.. Biological damages: As the historic building materials are natural and often have organic components inside, they offer good circumstances for biological attack vvhenever they are damp especially when ventilation isn't enough. in chapter 4, the sources of vvater causing the building become damp and the ways they get into the building materials are explained briefly. Dampness in historic buildings depends on three main sources:. Dampness rising from the ground,. Rain vvater,. The vvater vapor existing in the air. Here are explanations of the problems of these sources:. Rising damp affects the building elements, both the vvalls and the slab floors, in contact vvith the ground by means of the capillary action. When dealing vvith rising damp the position of the vvater table of the ground and the building foundations, in relation to each other is of great importance. The parts of the building belovv the vvater table are affected by vvater vvith pressure. The parts above the vvater table are affected by capillary action and the evaporation from the ground vvater. The rain vvater may gather around the building because of the vvrong sided slope of the ground surface ör damages in the rain disposal systems. Because of the lack of the damp proofing system (dpc) most of the historic buildings suffer from this problem. xii The most damaging property of the rising dampness is the salts solved in vvater carried till the evaporating area and gathered and crystallized by evaporation of the vvater. This gathering damages the pore structure and causes the surface fail off if it occurs behind the surface and this action repeats after each fal).. Rain vvater mostly affects the outer surface of the envelope. The range of damage depends on the duration of it, wind effects accompanying the rain, the angle rain vvater hits the envelope. Some of the ways in which rain vvater affects the building are:.. Penetration through the defected rendering... Flovving tovvards the building because of the defected eaves and instead of falling apart svveeping the surface being absorbed by the building materialby capillary action... Damages the wall because of the defected gutter systems... Rain vvater rarely passes through the building envelope, but vvith its cooling effect it may cause condensation inside... After gathering around the building rising through the vvall as explained in the rising dampness section... The form of snow applies big amounts of gravity on the upper envelope... Öne of the greatest damages of rain vvater occurs when the temperature drops to minus degrees after the surface are saturated by heavy rains, because of freezing as explained in chapter 3.. The problems depending on the vater vapor existing in the air: The vvater vapor condenses vvhenever meets a temperature belovv dew point either on the surface of building elements ör inside them vvhile diffuston.After condensation the vvater is absorbed by the element by capillary action depending on the absorbing properties of it... The vvater vapor existing in the air affects surface of the building elements either by means of condensation vvhen meets temperature belovv the dew point ör by hygroscopic materials vvhich collect vvater vapor from the air vvhen the relative humidity is above 70-75 % The masonry historic building elements are often thick, so have high heat capacities. So they are often much more cooler than the adjacent air, and often the cooling affect of the other dampness problems increase the risk of this phenomena. in spring and summer time the höt humid air of outside enters the cold inside and as the temperature drops the relative humidity rises and condensation occurs on the cold surfaces. The temperature of ground follovvs the airs rise a few months behind so in summer vvhen the air is höt vvith its high dew point but lovv relative humidity, the coldest periods are prevalent under ground, so the basement elements get cooler because of the heat looses. in vvinter vvhen intermittent heating system is used during the heating period the dew point rises by the gain of vvater vapor from other sources, vvhen the heating system is stopped the temperature of the inside air and the temperature of the elements drop and condensation occurs. xiii Because of the altering of night and day temperatures the outside air condenses on the outer sides of buildings sticking the aerosols on the surface. The hygroscopic materials gathered on the surfaces because of several phenomena attacks the vvater from the air and condenses above the dew point... The vvater vapor diff uses through the building elements because of the difference of vapor pressure of two sides. it condenses inside the element when meets a temperature belovv the dew point. The range of diffusion is affected by the vapor diffusion resistance factor (//) vvhich depends on the pore structure, grain properties and the moisture content of the material. Just like the surfaces, inside of the thick masonry is obviously cold, in fact colder than the surface. When dealing with modern buildings it is possible to estimate the risk vvhether it occurs and if dries completely during drying period. When dealing with historic masonry the thickness of the elements and the variability of the physical properties ali through the element because of either the differences of moisture contents ör the variable properties of the natural materials makes the problem more complicated. As the traditional building materials are mostly hygroscopic the diffusion is affected a lot. The brief descriptions of the dampness phenomena have great importance to distinguish the source and to overcome it by exterminating the conditions causing it to occur. in chapter 5, the steps of diagnosing the sources of dampness are introduced:. Investigating the building to gather the evidence.. Foresearch and observation.. Measuring moisture contents of the building elements.. Measuring the humidity of the air and the surface temperatures. Deducing the evidence, obtained by investigation, comparing them with the characteristics of the dampness problems of each type.. The investigation consists of three synchronous steps:. Foresearch and observation: in this step ali the evidence about the building are gathered, vvhich are possible except measuring moisture contents of the building materials and humidity of the air. Ali kinds of damages are observed searching the reason-conclusion relation. Every property of the building vvhich may affect the dampness such as the history of it, building materials and technic, heating system, its environment, the kinds of the chemical and biological defects by means of laboratory work, ete. are investigated and marked on the dravvings.. Measuring dampness state of the building elements: To produce dampness maps of the building both in section type and the surface öne. These xiv measurements are made by either sampling or by in situ methods. The sampling methods may damage the building during getting the samples, on the other hand the moisture meters used most widely depending on electricity conductance of damp material is affected by the salts a lot. The micro-wave moisture meters are also available and very usable, but because of their high cost difficult to obtain.. Measuring the humidity of the air: This step is necessary to find out if condensation occurs, the dew point of the air is compared with the surface temperatures whether they are below dew point or not. The humidity of the air is measured by means of:.. hygrometers with the usage of the psychrometric charts... measuring the moisture contend of the wood in hydric equilibrium with the air and deducing the relative humidity using the related deriving charts. The most important factor of measurements of the humidity of air is the time as condensation doesn't occur permanently. On the other side the temperatures of the surfaces are measured to compare with the dew point. ? Deducing the source and the type of the problem is made by comparing the evidence and the characteristics of the dampness problem. Here the moisture contend maps are of the greatest use, with the higher dampness values near the source. In chapter 6, the methods used to solve moisture problems are introduced and discussed whether they are really suitable. A real solution of a dampness problem means not only repairing the damaged parts of the building, but exterminating the circumstances causing it. Several methods can be used together. ? The methods used to combat the rising dampness can be summarized as:. Affecting the amount of evaporation through surfaces either increasing or decreasing.. Collecting the ground water and transferring it away from the building by means of drainage systems.. Cutting systems: Cutting the capillaries by inserting either physical or chemical barriers.. Electro-osmosis: In either active or passive way an electric system is installed. The active system depends on the belief that direct circuit drives water from anode to cathode, building up a electricity current the water is driven downwards. Passive system depends on the belief that there is a potential difference between lower and higher parts of the wall and this drives the water to higher parts of the ground. Connecting the higher parts to the ground building up a short circuit is supposed to stop the rising damp. Both systems are doubtful whether they are really successful or not. ? The rain water effects are eliminated by repairing the faulty building parts xv and using vvater repellents, but to use a water repellent is of a great risk in the point of initial condensation.. The condensation problem can be solved by means of preventing the building fabric's temperature drop belovv dew point. This can be achieved shortly in these ways:. To control the temperature of the element, preventing it to drop belovv dew point.. To control the humidity ör the temperature of the air to decrease the dew point and relative humidity. in chapter 7, the importance of the control process is stated. in chapter 8, the dampness problems of a historic masonry building are investigated in the ways described in previous chapters. Finally, ali the knovvledge obtained by the search are gathered as a scheme that consists of the necessary steps to combat a dampness problem. This scheme consists of synchronpus ör consecutive steps which should be follovved depending on obligation for ali dampness problems, obligations depending on the conclusions of the previous steps ör no obligation. This scheme is valuable to see ali the contents of the combating process together. This scheme is helpful in the organization of the combating system. it can be used as a basis for a detailed system for instance it can be expanded to the equipments commercially available.