Staining and soiling account for the most obvious or conspicuous forms of changes in a building’s appearance. Staining is defined as a mark or discolouration that is not easily removed. The build-up of stains on building surface at a time before it is normal or expected can be termed as premature staining. Staining or premature staining on building surface of new buildings has gained much attention in recent years.
Factors that contribute to staining include material, exposure, design, colour, water absorptivity, dirt retention, texture and solubility. Stains form primarily from the surface flow of water (runoff) down the facade. Water brings along dirt particles that is retained on the façade material. When the water dries out, dirt particles that are not washed off manifest as stains.
Buildings need to be designed to be more maintainable so that resources used on cleaning and maintenance work may be minimised.
“Bio-fouling” is a term used to describe the defacement of external and internal surfaces by organic contaminants. It can easily disfigure an otherwise attractive surface.
Microorganisms such as fungi and moulds usually cause organic staining on wall, ceiling and floor surfaces. These can have adverse health effects (e.g. mainly respiratory ailments such as asthma, rhinitis, etc) as well as aesthetic implications.
The main forms of defacement that affect property are listed in Table 1.
StainingTypeExternalInternalBiologicalAlgaeLichenMouldAnimal excrementMouldCobwebsSlimeHuman soilingPhysicalSootGrimeDampness (seismic/ rainwater staining)Dampness (general)EfflorescenceGraffitiOilRustWater-soluble chemicals such as sulphates causing yellow stains on stoneworkTobaccoGrimeGreaseDampness (tide mark)Pattern (thermal)Hygroscopic saltsGraffitiOilRustWater-soluble chemicals such as sulphates causing yellow stains on stonework
According to Diamant (1977), if a wall or ceiling is evenly insulated throughout, the dust tends to be deposited evenly. One of the most annoying aspects of the existence of thermal bridge or irregular insulation of walls and ceilings is the formation of dirt patterns. The reason for this is that air molecules (Brownian movement) are constantly bombarding suspended dirt particles. As hotter air molecules move faster than colder ones, there is a concentration of dirt particle over the colder areas of the wall and ceiling, since they are exposed to different impact momenta in different directions. The particles move slower over cold sections and therefore tend to deposit on these.
When the particles finally settle they naturally deposit themselves upon the wall and ceiling areas with the lowest surface temperatures. Thus it can be considered that the distribution of pattern staining is a direct measure of the surface temperature of the wall and ceiling and consequently of the thermal insulation properties of the materials beneath.
In the case of an un-insulated plaster boarding and rafter ceiling, lighter lines trace the position of the rafters. If the space between the rafters is insulated by means of glass fibre, while the timber rafters are not, the pattern is often reversed, although it is not as pronounced due to the fact that the difference in temperature between the surface affected is reduced.
In the case of wall, the maximum amount of pattern staining is usually found near the ceiling and the floor due to the thermal bridges formed by flooring connections.
Pattern staining is also found near corners, but the actual corner itself is usually much lighter than its surroundings as the corner is generally better insulated than the wall surfaces on either side.
A further manifestation of pattern staining is the blackening of walls above heating elements, such as hot water radiators or electric fires, and the blackening of patches around electric light bulbs. In these cases, it is difficult to prevent the staining except by the provision of shields to stop the dust particles from alighting on wall and ceiling.
Bricks are usually durable materials that age gracefully and require minimal cleaning. Nevertheless, dirt staining and efflorescence di cause bricks to lose their aesthetic value over time. Table 2 shows some cleaning methods for brick walls of various condition.
Dirt stains and biological growth could be water blasted to remove them from the brick wall. Efflorescence has to be brushed or scraped off from the surface whenever the salts appear. Brick masonry can generally be cleaned with chemicals in conjunction with water rinsing. Acidic cleaner containing dilute mineral acids such as hydrochloric, hydrofluoric, phosphoric and/ or organic acids such as acetic and citric acids are used to remove heavy soiling from most bricks masonry walls. The cleaning process involves applying the diluted cleaner to the pre-wetted surface and allowing a short dwell period. Chemical and soiling residues are removed by pressure water rinsing. The use of acid should be avoided in cases when steel accessories are incorporated in the brick wall. Bricks with high iron content may also be reactive to acids. Sometimes alkaline cleaners are used to remove soiling on brick surfaces, but the type of chemical cleaner should be selected with care, and then tested on small areas before it is used to clean the whole area. Certain chemicals may cause staining on some types of bricks. Soft bricks are particularly vulnerable to damage from aggressive cleaning methods. Cleaned bricks should be coated with a water repellent sealer to prevent bricks from getting wet.
If staining affects a large portion of a facade, it may be more economical to paint over the brick surfaces.
Table 2 : Cleaning and maintenance of brick wall<br />Condition of Brick Wall Cleaning MethodDirt on brickClay bricks Glazed bricksOrganic stains should first be removed with detergents before other chemical agents are used. If the texture of the brick is rough, pressurised water cleaning (<700 psi may be used in conjunction with light brushing with fibre brushes, but taking care not to initiate efflorescence.Surface soiling may be cleaned using a water rinsable neutral liquid detergent. Soiling beneath cannot be removed.Biological stainingRemoved by brushing with fibre brushes or in conjunction with water spray or chemical cleaning using a solution of muriatic acid.Green/buff or cream coloured stains from Vanadium salts (newly erected brick wall)Scrub with a solution of 10% hydrochloric acid containing detergent at 0.1% of the total acid solution and wash thoroughly with water. Leave the wall alkaline by washing with potassium hydroxide (50g/L).Paint on wallMay be removable with water rinsable paint removers to BS 3761: 1995. Alkaline-based agents may also be useful. The surface should be rid of residual resins and pigments by washing with a high-pressure water lance.Walls with efflorescenceShould be allowed to weather away over time. May be removed by dry brushing with a stiff bristle brush and rinsing with water. The residue should not be allowed to re-enter the brick wall at lower levels. Chemicals should not be used.Walls with lime stainsWashing with dilute acid. The wall should be wetted with water before the acid is brushed on. Upon removal of the stains, the wall must be rinsed clean with water again.Iron and manganese stains(light brown to black)Chemical cleaning using 5% or 10% hydrochloric acid or painting the stains over with oxalic acid solution (12Og/L).<br />
Exposed concrete is prone to staining due to surface irregularities. Regular cleaning once or twice a year, with high-pressure water jet or a non-toxic and mild acidic-based solution is required to keep the building from staining. Stains caused by rain that washes the dirt and dust, and algae growth are generally repairable by simple washing and scrubbing at the stained area (Table 3).
Table 3 : Cleaning and maintenance of concrete wall<br />Condition of Concrete Wall Cleaning MethodAtmospheric soilingLow-pressure water washing from top down. High pressure water jets should not be used as it may drive the stain further into the concrete. If insufficient, it could be supplemented by the following order: brushing with a soft brush, a mild soap, a stronger soap, ammonia or vinegar.Severe soilingChemical cleaningAmmonium hydroxide. sodium hypochlorite or hydrogen peroxide may be used with dilution. The surface should be flushed with water before and after washing to prevent etching by acidic agents. Chemicals containing salts may damage concrete due to adverse reactions.Mechanical cleaningInvolves power tools such as grinders, buffers, chisels. Brushes or steam/ flame cleaners. Concrete may be removed along with the stain to result in a roughened or uneven surface.Organic stains that cannot be removed with solvents may be burnt off with flame cleaners. However, the heat may cause part of the concrete surface to scale off.Biological stainingHeavy growth should be removed by brushing with stiff fibre brushes, wooded spatulae, scrapers or a low-pressure water lance. Biocide should be applied to inhibit further growth.Oils stainsMay be removed by applying an emulsifying or degreasing agent. Deep stains should be poulticed with white spirit or tricholoroethane. The deposits should be then removed with hot water pressure lance or with steam.Condition of Concrete Wall Cleaning MethodWalls with efflorescence/ lime stainsUsually disappears itself by natural weatheringMay be removed by washing with a 5% solution of hydrochloric acid. Alternatively, brushing with soft compact brushes and sponging the residual powder away may be more effective since excessive wetting with water may initiate further efflorescence formation.<br />
Natural stones may be generally classified into two general categories based on its composition: siliceous or calcareous. The former tends to be more durable and relatively easy to clean with neutral cleaning solutions. The latter is sensitive to acidic cleaning agents and requires cleaning with specially formulated stone cleaners.
Natural stones are basically porous and they absorb spills and stains if left untreated. Sealers with repellency properties against weathering and ultra-violet rays may be considered to minimise cleaning work.
Cleaning by water coupled with scrubbing or high-pressure water jet could effectively remove most of the stain from stone cladding surfaces (Table 4). Cleaning should begin at the top so that excess water can run down and pre-soften the dirt below Acidic cleaning agents should not be used for granite as they may attack the pyrite (iron sulphide) which is inherent in granite to result in brown stains. It is also not proper to use cleaners that contain petroleum (which may change the appearance of the stone) or products that contain other acids or abrasives that may scratch the surface.<br />Table 4 : Cleaning and maintenance of natural stone wall<br />
Condition of Natural Stone Wall Recommended Cleaning MethodUnpolished Granite(Atmospheric Soiling)Polished Granites(Atmospheric Soiling)Chemical/ abrasive methods needed. Agents containing hydrofluoric acid may be useful. Alternatively. use alkaline cleaners followed by neutralisation with weak organic acid.May be removed with non-ionic soap and scrubbing in water. Surfaces should be thoroughly rinsed and wiped dry to prevent water spotting.Visual inspection every five years. If necessary cleaning re-pointing and surface repairs in accordance with BS 6270:Part IStrong acidic cleaning agents should not be used as it attacks pyrite (iron sulphide) inherent in granite to result in a brown stain.Apply silane-based impregnating agent every 5 years to seal stone against dirt and pollutants.MarbleWater soluble sooty particles Metallic, oil or grease stainsWashing with small quantities of water. Soften the dirt by hand-spraying, followed by scrubbing with bristle brush and hand- spraying to remove dirt.Remove with liquid detergents. It stains persist, use acid or alkali based agents.Acids, phosphorus, chlorine or scouring powder should not be used. Hard water will encourage discolouration, particularly if iron is present, and cause the build-up of insoluble salts. Re-polishing maybe required on a regular basis.SandstoneChemical cleaning using hydrofluoric acid and orthophosphoric acid-based agent. Or dry air abrasion cleaning using mineral slag abrasive agents.Condition of Natural Stone Wall Recommended Cleaning MethodStones with Efflorescence/ Lime StainsRemove by brushing with fibre brushes or in conjunction with water spray or chemical cleaning using a solution of muriatic acid.Biological StainingRemove by dry brushing with wooden scrapers or bristle brush or by high pressure water jetting. Surface should then be treated with anti-fungicidal wash.
Table 5 : Cleaning and maintenance of tiled wall
Condition of Tiled Wall Recommended Cleaning MethodCeramic TilesGeneral cleaning by wiping with Wet cloth or scrubbing with sponge. For heavier soiling, use a mild detergent solution and leave it on the surface for 5 minutes before scrubbing lightly with a brush.Mosaic TilesGeneral cleaning by wiping with damp sponge mop. For heavier stains, cleaning agents can be supplemented with brushing. Pressure blasting can also be considered to wash away dirt trapped at the joints.Efflorescence/ Lime StainsRemoved by dry brushing or with water and a stiff brush. Heavy efflorescence or lime stains may be removed with mineral acids such as hydrochloric, sulphuric and nitric or other organic acids. Wet the surface well before and after the solution is applied.MildewRemove with a dilute solution of ammonia or bleach. Concurrent scrubbing may be needed.Biological StainingUse a weak acid such as vinegar.<br />
Table 5 summarises the common staining problems with external tiled wall and shows examples of maintenance strategies. The dirt stains will be more concentrated at the mortar joints since mortar has a higher porosity and absorbs water quickly to leave behind dirt particles within the joints. If a sealant is used at movement joints and the sealant fails and becomes sticky, it will hold dirt until it rains. Dirt is then deposited in streaks down the building, emanating from that point. Depending on the tiles used and the extent of staining on the surface, cleaning agents can be selected according to the state of staining. Care should be taken during the selection of cleaning agents as abrasive agents can easily etch the tiles, making them more vulnerable to dirt. Tiles used should be glazed and of darker colour to mask excessive dirt stains.<br />
The appropriate type of cleaning method used is determined by the degree of soiling, the size, shape and location of the surface to be cleaned. The cleaning specifications should be followed closely with respect to the frequency and method of cleaning (Table 6).<br />It is preferable to clean metal surfaces in the shade as possible chemical reactions on hot metal surfaces may be highly accelerated and non-uniformity can occur. For slightly soiled surfaces, cleaning should be done with water and some detergent. It should be completed by carefully rinsing with clear water and wiping with a soft and absorbent cloth. For moderately soiled surfaces where the soiling cannot be removed by normal detergents, it is recommended that products which are developed especially for this purpose be used. These products may contain detergents and very light abrasive materials. For very dirty surfaces where the dirt is very stubborn, it may be necessary to apply the same means as mentioned above but with the use of synthetic pads.<br />There are many ways to clean metals, from using plain water to harsh abrasives. The mildest possible method should be used, particularly for anodised aluminium. The following cleaning materials and procedures are listed in ascending order of harshness. The mildest treatment should be tried on a small area and if the results are not satisfactory, the next method may be examined.<br />
The procedure for cleaning should begin with applying the cleaning solution only to an area that can be conveniently cleaned without changing position. The surface should be thoroughly rinsed with clean water before applying the cleaner. Cleaner rundown should be minimised on the lower portions of the building and such areas should be rinsed as soon and as long as it is practical. The metal panel should be dried with a clean cloth to prevent streaking. There should be no concentration of the cleaner at the bottom edges of the aluminium. If abrasives are used then the appearance of the metal finish may be altered. If there is a grain in the finish then cleaning should always be with the grain. When all other methods fail it may be necessary to resort to heavy-duty cleaning. This involves the use of cleaners containing strong etching chemicals or coarse abrasives.<br />Cleaners containing strong organic solvents will have a deleterious effect on organic overlay coatings, but not on anodised aluminium. However, the possibility of solvents extracting stain-producing chemicals from sealants and affecting the function of the sealants must also be considered.<br />Depending on the causes of staining, different measures can be taken to mitigate its influence. In most cases, only cleaning work is needed. However, if the staining is caused by the degradation of cladding materials and sealant, the replacement of the defective element is needed.<br />Table 6 : Cleaning and maintenance of metal wall<br />
Condition of Metal Wall Cleaning MethodAluminiumAnodic CoatingLightly soiled Heavy soilingFlush surface with water at moderate pressure. Use mild detergent. and brushing or sponging concurrently if necessary.Scrub with a nylon-cleaning pad wet with surface protective material. Rinse surface with water and wipe dry with a chamois. squeegee or lint-free cloth or air dry.Power cleaning tools (e.g. air-driven reciprocating machine fitted with abrasive pads) and mild detergent can also be used. Direction of travel of machine with respect to geometric configuration of the surface being cleaned should be noted.Powder CoatingLightly soiledHeavy soilingFlush surface with water at moderate pressure. Use mild detergent, and brushing or sponging concurrently if necessary.Mild solvent (e.g. mineral spirits) may remove grease, sealant or caulking compounds.Dried concrete stains can be removed with diluted muriatic acid (under 10%). Vigorous rubbing with non-abrasive brushes or plastic scrapers may be necessary.Some solvents may extract materials from sealants and cause staining or damage the sealant.Abrasive cleaners containing ketones, ethers or alcohols and steel wool should not be used.Coatings may require re-decoration after 10—15 years.Clean polluted/marine areas every 3 months, other areas every 6 months.Condition of Metal Wall Cleaning MethodSteelDirt and pollution ChloridesFingerprints, grease, oilMay be removed by rinsing with water and mild detergent, then scrubbing in the direction of the grain with soft cloths, sponges, fibrous brushes, or plastic pads. Abrasive actions should however be minimised since these may scratch the finish. Steel wool/ brushes will causing pitting and should not be used.Remove with warm water.Remove with a combination of water, mild detergent, and mineral spirits.Iron stains (from bolts, screws. etc)Graffiti (Water soluble inks) Other inks and paintLead pencil markingsWeld stainsCorrosion productsRemove rusty elements and immerse them in nitric acid. Use warm water and a non-ionic detergent and rinsing with water. Use a combination of water. non-ionic detergent and mineral spirits and rinsing with clean water.Remove with an oily cleaner such as paste wax. Remove with mild abrasive cleaner in paste form and water.Remove with warms water, detergent, and plastic pads. If severe, mechanical methods (e.g. grinding or sandblasting) may be appropriate. Surface refinishing with fine abrasives to restore to original.Clean polluted/marine areas every 3 months, other areas every 6 months.Annual inspection and maintenance in accordance with BS 5427: Part I. Table 9.Biological StainingFungicide. Leave on wall for up 107 days. All traces of the fungicide and effluent should be removed and the surfaces thoroughly rinsed with water.
Table 7 shows the common maintenance methods for glass facades. The procedure for cleaning glazed surfaces begins by wringing a cloth, sponge, or chamois until it is almost dry before wiping the glass surface. The wet surface is then dried with newspapers, paper towels, window wipes, or a chamois. Avoid washing windows in direct sunlight because they tend to streak and are more difficult to clean.<br />Table 7 : Cleaning and maintenance of glazed surfaces<br />Condition of Glass Wall Cleaning MethodSoiled and greased glassHard water deposits and soilWring out a cloth, sponge, or chamois almost dry before wiping the glass surface. Use an alkali, such as ammonia or baking soda or washing soda. Dry the wet surface with newspapers, paper towels, window wipes, or a chamois. Avoid washing windows in direct sunlight because they tend to streak and are more difficult to clean.Use a weak acid such as vinegar (a strong acid would etch the glass).Avoid cleaning glass under direct sunlight as they tend to streak.<br />
Regular inspection of the coated surfaces is important in determining the seriousness of stains and the frequency of cleaning required.<br />The use of alticides, washing and repainting of walls regularly (every few years) can keep stains and biological growth at bay. Care must be taken on painted surfaces as sunlight can actually penetrate through one or two layers of paint and cause growth underneath instead, and eventually break through the new layer of paint.<br />Stained plaster-and-paint walls are usually cleaned by washing and I scrubbing (Table 8). However if the stains are too serious and widespread, it is more appropriate to remove the affected surface coating, sand, clean and redo the coating.<br />Table 8 : Cleaning and maintenance of painted wall<br />Condition of Painted Wall Cleaning MethodOil paintSemi-gloss paintsGloss paintsWater paintsWash with water and a non-abrasive weak alkaline detergent (e.g. hand dishwashing liquid). Stronger solutions may remove some of the paint.Walls should be cleaned upwards commencing from the bottom and in a sideways manner. This prevents staining of the surface by water.Wash with a non-abrasive weak alkaline detergent using less water. Hard-bristled brushes should not be used.Walls should be dry brushed regularly and washed only once a year.Water and a weak detergent may remove atmospheric dirt on the surface. Rinse with clean water after washing.Small build-up of dirt may be removed using light sponging with a weak detergent and clean water. Excessive water should not be used as it may damage the finish. Regular cleaning by dry brushing is recommended.<br />
Pudu Prison was a well-known historical attraction in the Kuala Lumpur city centre, its large area of 8.8ha in Jalan Hang Tuah, Kuala Lumpur, is a prominent landmark in the nation’s capital city. 114-year-old Pudu Prison standing there had been witness how Kuala Lumpur step into a big city.
Figure 1 : Location of Pudu Prison, Kuala Lumpur
Pudu Jail or Pudoh Gaol, The historic Pudu prison was built and designed in 1891 and completed in 1895 by state engineer and director of Public Works Department, Charles Edwin Spooner. At the cost of RM 138 000 ($320 000), the prison was built in six phases using steel, brick and cement, all imported from British colonies India and Britain.
Its design was copied from the Kandy Prison in Bogambia, Africa for shaped like a butterfly or an X structure (cruciform). It originally had 240 cells on three floors, but more cells were added over the years. It had mass kitchen, bathrooms, administrative office, hospital and training centre are located outside the main X-building structure.
Figure 2 : Layout pelan of Pudu Prison<br />Figure 3 : View of Pudu Prison from high angle<br />The prison’s gruesome condemned cell is located at block D where those on death row were prepped before being hanged at the execution room in the same block. Between 1960 and 1993, 180 convicts were hanged there. Pudu Prison was designed to house 600 inmates initially but with additional cells, its capacity was increased to 2,000.<br /> <br />The Pudu Prison main entrance was situated in a two-storied building. The Administrative Offices was on the ground floor and on the top floor, six cells for European and Eurasian prisoners and two small rooms for storage of prison records. The female ward of the prison and the prison kitchen were separate areas on each side of the Administrative Block and leading from the main section of the prison were four three-storied wings. The prison hospital was close by, but separate from the main building.<br />During World War II, the Japanese occupation forces incarcerated many English, Australian and New Zealand prisoners in this prison.<br /> <br />Mural painting along prison’s wall<br />Figure 4 : 4.5 m high x 384 m long mural on prison’s wall<br />A prominent feature of the prison is the mural painting on its outer walls done by former inmate Khong Yen Chong in the early 1980s. The wall murals of tropical scenes painted by the prisoners took them over a year to paint using 2000 liters of paint. The murals entitled the inmates to won a place in the Guinness Book of Records, for painting the world’s longest mural along the prison’s walls stretching out to more than 384m long and 4.5 m high.<br />Figure 5 : Khong Yen Chong whose painted the mural <br />Figure 6 : Legendary robber ‘Botak Chin’ was executed in Pudu Prison<br />In 1981, it saw the execution of legendary robber “Botak Chin”. In 1985, the prison recorded its highest number of inmates at any one time with 6,550. This forced the prison authorities to arrange sleeping shifts for the prisoners.<br /> <br />In 1986 execution of Kevin Barlow and Brian Chambers, both Australian nationals, for the drug trafficking of heroin was the last serve. The colonial era prison was officially closed in November 1996. The old Pudu Prison has been identified as one of the major sites for mega development. since then, All the inmates were then moved to the new Sungai Buloh prison built by the UDA.<br />As Kuala Lumpur attraction in early 2004, it was reopened just for a short time as a museum for public to witness the prison ambience. Those who have visited the Pudu Prison described the cells as totally horrific. Each cell is equipped with a window only the size of a shoebox.<br />Pudu Prison Kuala Lumpur was temporarily re-opened as an Alcatraz-style museum before being shut for good to enable the Urban Development Authority Holdings Bhd, which reportedly bought the 7.65ha site for RMl00 million from the Government, to turn it into a commercial area which is expected to cost RM83 million and will be completed by September 2011.<br /> <br />The land on which the prison structure stands has been earmarked for mixed development with 70% of the land will be used for a commercial hub and 30% for residential development. The old prison mosque will be maintained. The Hang Tuah monorail station will also be integrated with the proposed development site to create easy accessibility for the public.<br />
Methodology of Inspection
Identifying the precise causal factors of building defects is frequently an onerous task for any investigator (Addleson, 1992). Diagnosing defects is rarely a straightforward activity with few risks. Detection of a defect is usually undertaken by identifying certain indicators using most if not all the five human senses i.e visual, olfactory, aural, tactile and taste.<br />In this case, the method that used to inspect this house is by the human senses as shown in Table 9.<br />Table 9 : Methodology inspection : human senses<br />
FacultyExampleVisualLook for changes in appearance:StainingDiscolorationsIndentationDistortion or irregular patternOlfactoryTry to smell for unusual or foul odours:Mushroomy smell is indicative of dry rotObnoxious smell may be indicative of either a defective foul drain or a dead animal rotting in a hidden space.TactileFeel surface for unevenness, roughness or loose material (e.g. powdering and flaking of paint)Feel material for friability (i.e. the crumby state of mortar or wood is indicative of a problem)
There are varies of staining on Pudu Prison building. The stains founded are divide to non-biological, biological and physical types as shown in Figure X. From visual observation, most of the stains that occurred at the Pudu Prison is due algae and graffiti. As a<br />Figure 7 : Stains on Pudu Prison<br />
Report on staining on Pudu Prison
Stains locationExternalStain categoryPhysicalType of stainGraffitiCauseThe cause of the stain is due to human attitude. This graffiti also a kind of vandalisme by ‘anonymous artist’. Repair/ Prevention/ Clean RecommendationThe stains are too serious because it was done on the mural painting. It impossible to erase the aerosol spray graffiti that was sketch on the mural. The best way is to remove the affected surface coating, sand, clean and redo the coating. For the plain area that have graffiti, redo the coating could solve the problem.<br />Stains locationExteriorStain categoryBiologicalType of stainAlgaeCauseWhen condition are ideal, algae will appear in 1 to 2 years time. It may appear initially as either light green, blue green, or orange coloured filaments or powder which may be slimy when wet. Over time, dirt may collect over the mycelium to result in blackish and conspicuous stains.Blackish stainsRepair/ Prevention/ Clean RecommendationHeavy growth should be removed by brushing with stiff fibre brushes, wooded spatulae, scrapers or a low-pressure water lance. Biocide should be applied to inhibit further growth. After the treatment, re painting the area.<br />Stains locationExternalStain categoryPhysicalType of stainGraffitiCauseThe cause of the stain is due to human attitude. This graffiti also a kind of vandalisme by ‘anonymous artist’.Repair/ Prevention/ Clean RecommendationThe graffiti has to remove The stains are too serious because it was done on the mural painting. It impossible to erase the aerosol spray graffiti that was sketch on the mural. The best way is to remove the affected surface coating, sand, clean and redo the coating. For the plain area that have graffiti, redo the coating could solve the problem.<br />Stains locationExteriorStain categoryNon BiologicalType of stainAlgaeCauseDue to pollution in air. Acid rain will damage the painted surface. Exposure will caught dust and the area affected will look like blackish stain.Repair/ Prevention/ Clean RecommendationThe surface have to clean by high pressure water jetting and repainting with suitable outdoor paint.<br />Stains locationExteriorStain categoryBiologicalType of stainAlgaeCauseWhen condition are ideal, algae will appear in 1 to 2 years time. It may appear initially as either light green, blue green, or orange coloured filaments or powder which may be slimy when wet. Over time, dirt may collect over the mycelium to result in blackish and conspicuous stains.Repair/ Prevention/ Clean RecommendationHeavy growth should be removed by brushing with stiff fibre brushes, wooded spatulae, scrapers or a low-pressure water lance. Biocide should be applied to inhibit further growth. After the treatment, re painting the area.<br />Stains locationExternalStain categoryPhysicalType of stainGraffitiCauseDue to human attitude.Repair/ Prevention/ Clean RecommendationRepainting the area since there are plain wall.<br />Stains locationExternalStain categoryBiologicalType of stainAlgaeCauseWhen condition are ideal, algae will appear in 1 to 2 years time. It may appear initially as either light green, blue green, or orange coloured filaments or powder which may be slimy when wet. Over time, dirt may collect over the mycelium to result in blackish and conspicuous stains.Light green and slimy algaeBlackish stainsRepair/ Prevention/ Clean RecommendationHeavy growth should be removed by brushing with stiff fibre brushes, wooded spatulae, scrapers or a low-pressure water lance. Biocide should be applied to inhibit further growth.<br />Stains locationExternalStain categoryBiologicalType of stainAlgaeCauseWhen condition are ideal, algae will appear in 1 to 2 years time. It may appear initially as either light green, blue green, or orange coloured filaments or powder which may be slimy when wet. Over time, dirt may collect over the mycelium to result in blackish and conspicuous stains.Repair/ Prevention/ Clean RecommendationHeavy growth should be removed by brushing with stiff fibre brushes, wooded spatulae, scrapers or a low-pressure water lance. Biocide should be applied to inhibit further growth.<br />Stains locationExteriorStain categoryPhysicalType of stainDampnessCauseRising damp is the upward movement of ground water through the pores of a permeable masonry wall via a process called capillarity. Capillarity is the same process that enables the movement of water from tree roots to tree tops via intricately stacked hollow cells despite the counteractive force of gravityRepair/ Prevention/ Clean RecommendationSince the dampness are happened for a long time, the area should be refurbish by clean the area using water jetting and repainting the wall using exterior paint. <br />Stains locationInternalStain categoryPhysicalType of stainGraffitiCauseThis problem due to human attitudes. Repair/ Prevention/ Clean RecommendationSince the stains is only a water soluble ink stains, it could be remove by clean the area using high pressure water jetting and repainting the wall.<br />Stains locationInternalStain categoryPhysicalType of stainGraffitiCauseThis problem due to human attitudes. Repair/ Prevention/ Clean RecommendationSince the stains is only a water soluble ink stains, it could be remove by clean the area using high pressure water jetting and repainting the wall.<br />Stains locationInternalStain categoryPhysicalType of stainGraffitiCauseThis problem due to human attitudes. Repair/ Prevention/ Clean RecommendationSince the stains is only a water soluble ink stains, it could be remove by clean the area using high pressure water jetting and repainting the wall.<br />REFERENCES<br />
Michael Y L Chew & Tan Phay Ping, 2003, Staining Of Facades, World Scientifc, Singapore
James Douglas and Bill Ransom, 2007, Understanding Building Failures – Third Edition, Taylor & Francis, London
Edward A. Noy Revised by James Douglas, 2005, Building Surveys and Reports – Third Edition, Blackwell, London
John Hinks & Geoff Cook, 1994, The Technology Of Building Defects, Taylor & Francis, London