Preliminary Assessment of Dampness in Walls of Residential Buildings in Four Climatic Zones in Ghana

A questionnaire survey of inhabitants of 5,800 residential buildings was conducted in the Dry Equatorial, South Western Equatorial, Tropical Continental and the Wet Semi Equatorial climatic zones in Ghana to identify the most severe symptoms associated with dampness in the walls of residential buildings. Onsite building investigations were also conducted by trained assessors to identify the lead source of dampness in the walls of these residential buildings in Ghana. Data were analyzed using frequency and severity index. Majority of the houses surveyed were of lateritic materials and sandcrete block walls. The results showed that the most dominant symptoms in the walls of the residential buildings surveyed were hygroscopic salts, decayed skirting, dampness below 1.5m and mold growth on walls up to 1m high. These symptoms point to the presence of rising dampness as the lead source of dampness in the walls of these residential buildings. The results provide a platform for addressing the problem of rising dampness in buildings.


Introduction
Buildings have an expected lifetime of 60 to over 100 years, during which they offer shelter from the weather to human beings, animals and properties.Weather and its variations cause degradation of building materials and structures (www.chalmers.se/.../building).When designing a sustainable building, it is important to take into consideration the location, natural shading, shelter (from storms, etc.) and structural materials (Cukierski, 1999).This is because certain parameters such as ambient air temperature and humidity, solar radiation, wind, precipitation and ground water cause different processes of deterioration in buildings.Serious environmental problems can also arise where existing buildings have other design problems.A common problem that can result from such conditions is moisture problems.Typical of these moisture problems is rising dampness, a type of dampness which occurs where ground water is conducted up through a masonry wall or a concrete floor slab.Moisture can damage shelving and increase humidity in a building (Cukierski, 1999).Dampness in buildings is one of the most widespread problems associated with both historic and modern types of buildings (Hetreed, 2008;Karoglou et al., 2007;Burkinshaw & Parrett, 2004).Moisture in general causes damage to the exterior and interior walls of buildings, high heating energy consumption and uncomfortable indoor environment for occupants (Karouglou et al., 2007).The building envelope restoration suffering from moisture problems is one of the critical issues in sustainable refurbishment of buildings (Karouglou et al., 2007).The transfer of moisture in buildings is a very complex issue and has been a topical issue for decades.Moisture in buildings can cause deterioration of buildings by damaging brick/block work, cause decay and breaking up of mortar joints, fungal attack in timber and corrosion in iron and steel as well as stained wall surfaces internally and externally (Trotman et al., 2004).Damp surfaces encourage the formation of mold, and the spread of mold and mites in conditions of high relative humidity is associated with ill health (World Health Organization, WHO, 2009).Damp conditions also typically affect the mental health of dwelling occupants, causing depression and anxiety, particularly where there is damage to decoration from mold or damp staining (Nicol, 2006).As the most frequently reported cause of building deterioration, dampness in all its forms has assumed an alarming proportion and countries like the United Kingdom, United States of America, Australia, Denmark, Canada, Japan, Estonia, Iceland, Norway, Sweden, Taiwan, etc. have

Dampness in Buildings
Dampness can be defined as water penetration through the walls and certain elements of a building (Halim et al., 2012).Dampness can also be defined as an excessive quantity of moisture contained in building materials and components which causes adverse movements or deterioration and results in unacceptable internal environmental conditions (Briffet, 1994).Burkinshaw and Parrett (2004) defined dampness as the amount of moisture content present in a material and can be classified as capillary moisture content, equilibrium moisture content, hygroscopic moisture content, total moisture content and potential moisture content.Dampness is the most frequent and main problem in buildings and contributes more than 50% of all known building failures (Halim et al., 2012;Trotman, 2004).According to Hollis (2000), dampness is inextricably linked to most building deterioration.A source of water close to a building will also be one of the problems associated with dampness.These problems include symptoms such as dirty spots on the building, biological plants like the growth of fungi, mosses and creeping plants, paint flaking, blistering etc. (Halim et al., 2012).In order to successfully diagnose and make appropriate recommendations for remedial actions, one should understand dampness and its impact on buildings.
The ultimate objective of any dampness study is to identify the lead source of moisture in order to recommend actions to remedy the problem (Halim et al., 2012).According to Hollis (2000), sources of dampness can be classified as rising dampness, penetrating dampness, condensation and pipe leakages.According to Burkinshaw and Parrett (2004), dampness can be classified as air moisture condensation, penetrating dampness, internal plumbing leaks, below ground moisture or building specific sources.
Rising dampness occurs as a result of capillary suction of moisture from the ground into porous masonry building materials such as stone, brick, blocks, earth and mortar (Halim & Halim, 2010;Ahmed & Rahman, 2010;Riley & Cotgrave, 2005;Trotman et al., 2004;New South Wales Heritage Office, NSWHO, 2005).The moisture evaporates from either face of the wall (inside or outside), allowing more to be drawn from below.The height to which the moisture will rise is determined by the evaporation rate and the nature of the wall (Halim & Halim, 2010;Ahmed & Rahman, 2010;Trotman et al., 2004;Riley & Cotgrave, 2005;NSWHO, 2005).The normal limit for rising dampness ranges from 0.5 m to 1.5 m above ground level (Halim & Halim, 2010;Ahmed & Rahman, 2010;Trotman et al., 2004;Riley & Cotgrave, 2005;NSWHO, 2005).Rising dampness may show as a high-tide-like stain on wall paper and other interior finishes, and, when it is severe, as blistering of paint and loss of plaster.Damp walls encourage the growth of mold which in conjunction with high humidity, can lead to health problems to occupants (Halim & Halim, 2010;Ahmed & Rahman, 2010;Trotman et al., 2004;Riley & Cotgrave, 2005;NSWHO, 2005).
Water penetration through a building enclosure depends on the simultaneous occurrence of three things: the presence of water; an opening through which water can enter and a physical force to move the water (Beall, 2000).Water can be present as rain, melting snow and soil moisture.Several forces such as gravity, air currents, capillary suction, surface tension, kinetic energy, air pressure and hydrostatic pressure influence the penetration of water into buildings (Beall, 2000).Drips from air conditioning or hot water system overflows, rain water, pipe leakages, water from horizontal directions, etc. can also cause penetration dampness in buildings (NSWHO, 2005).These sources tend to produce small, localized patches of dampness and decay, whereas rising dampness may affect the base of a whole building (NSWHO, 2005).
According to Curtis (2007), dampness resulting from condensation occurs where water in the air inside a building condenses on a cooler surface.This is usually indicative of cold spots in the building, sometimes called cold bridges (Curtis, 2007).It can also occur where there is poor ventilation or where short intense heating cycles do not allow the walls to fully warm up (Curtis, 2007).This situation allows the heated air to hold more water, which condenses when the temperature drops (Curtis, 2007).Excessive condensation frequently results in severe mould growth which can in turn create health hazards.Condensation is one of the most common forms of dampness in residential buildings, mainly caused by warm moist air formed from cooking, washing, bathing or even by just breathing, condensing onto colder surfaces in the homes (Burns, 2010).Damp patches can appear on plaster walls in odd places, particularly on outside walls, often appearing and disappearing on a regular basis (Burns, 2010).Condensation is mostly accompanied by mold which is black in colour but can virtually be of any colour and is very common on walls and ceiling, underneath bay windows, etc. (Burns, 2010).According to the British Research Establishment (BRE), 80-85% of dampness problems in the United Kingdom arise due to condensation or manmade moisture (Ryan, 2002).
There are many visual signs to look out for when diagnosing any damp situation (South Northamptonshire Council, SNC, 2012).In Denmark, rising dampness in the walls of buildings is associated with symptoms such as salt efflorescence, deterioration of rendering and plastering mortar, deterioration of wooden parts of buildings, etc. Condensation is associated with mold growth, usually on top of walls and ceilings (Burns, 2010).Rising dampness may show as a high-tide-like stain on wall paper and other interior finishes, and, when it is severe, as blistering of paint and loss of plaster (Halim & Halim, 2010;Ahmed & Rahman, 2010;Burns, 2010;Curtis, 2007;Trotman et al., 2004;Riley & Cotgrave, 2005;NSWHO, 2005).Mold growth may also be associated with rising and penetration dampness in buildings (Burns, 2010).The 1991 House Condition Survey found that 10.4million homes were affected by mold growth (Ryan, 2002;Wheeler & Critchley, 1998) and the Northern Ireland House Condition Survey in 1996 also found that 16% of homes experienced some form of mold growth (Ryan, 2002).

Diagnosing Dampness
Dealing effectively with the problem of dampness requires the adoption of an organized system of investigative procedures to confirm all the sources of dampness and to ensure that the recommended remedial works are appropriate (Halim et al., 2012).Such a system must commence with identifying and recognizing symptoms or signs of dampness (Halim et al., 2012).A professional who undertakes any form of building inspections should be aware of information already available (Carillion, 2001).The selection of an effective remedy for any form of dampness must start with a correct diagnosis of the cause (Carillion, 2001).There are four major stages to any dampness investigation.These are visual inspection, investigations using moisture meters/ non-destructive tests, a more detailed investigation/destructive tests and homing in on the problem/assessment study (Halim et al., 2012;Burkinshaw & Parrett, 2004).This study is a preliminary investigation and based on stage 1, thus the visual inspection stage.This procedure requires a surveyor to inspect the defect closely and it is the first of the four stages involved in any dampness investigation.This stage may be subjective and based on experience and skill of the personnel involved (Halim et al., 2012).The identification of a dampness problem is dependent on the symptom of defect i.e. staining of water, cracking, rotten timber, decay, blisters, etc. (Halim et al., 2012;Burkinshaw & Parrett, 2004).The diagnosis requires knowledge of the behavior of relevant building materials, construction knowledge and knowledge on the use (past, present and future) of the building.The surveyor needs to record the defect by description, photograph or sketch drawings, etc. (Halim et al., 2012;Burkinshaw & Parrett, 2004).

Research Methodology
The study was conducted through field surveys by trained assessors to identify the most severe symptoms and the lead source of dampness in walls of residential buildings in Ghana.The main instruments used for data collection were structured questionnaire surveys made up of closed-ended questions and a checklist for on-site building investigations by trained assessors.The questionnaires were administered to building occupants of residential buildings in the four climatic regions of Ghana.Four main climatic regions are distinguished in Ghana; South-Western Equatorial (SWE), Dry Equatorial (DE), Wet Semi-Equatorial (WSE) and Tropical Continental or Savanna (TC) (Abass, 2009).The principal characteristics of each climatic region are based on rainfall, temperature, humidity, etc (Abass, 2009).The South Western Equatorial Climatic zone is the wettest climatic region in Ghana.The rainfall regime is the double maximum type.Mean annual rainfall is above 1,900mm and on the average, no month has less than 25mm of rain.The highest mean monthly temperature of about 30°C occurs between March and April and the lowest of about 26°C in August.A typical station for this climatic region is Axim (Abass, 2009).The Dry Equatorial climatic zone has two rainfall maxima: but the dry seasons are more marked and the mean annual rainfall is considerably less-between 740 and 890mm.This region is the driest in Ghana.Temperatures are almost the same as in the south-west equatorial climatic region, and average monthly relative humidity is higher in the rainy seasons than during the rest of the year.A typical station for this climatic region is Accra.Cape Coast, Sekondi Takoradi and Ho also fall within this climatic region (Abass, 2009).The Wet Semi Equatorial Climatic zone has two rainfall maxima, but the mean annual rainfall is between 1,250 and 2,000mm.Some of the wetter areas include the Akwapim-Togo ranges and the Southern Voltarian plateau where annual rainfall sometimes exceeds the second rainy season (from September to October).A typical station for this climatic region is Kumasi.Other towns include Sunyani, Koforidua and Enchi (Abass, 2009).The Tropical Continental climate has a single rainy season from May to October followed by a prolonged dry season.The mean annual rainfall is about 1,000 to 1,150mm.Mean monthly temperatures vary from 36°C in March to about 27°C in August.A typical station for this climate is Zuarungu.Among the other towns in this zone are Navrongo, Bawku, Wa, Tamale, Salaga and Yendi (Abass, 2009).
The questionnaires distributed to the building occupants sought information about the type of buildings, the materials used to construct the walls and symptoms associated with dampness in walls identified from literature (Ahmed & Rahman, 2010;Burns, 2010;Trotman, 2004;Nicol, 2006;Riley & Cotgrave, 2005;CWC, 2000).
The respondents were asked to rank the level of severity of the symptoms associated with dampness in walls on the Likert scale of 1-5, where 1=Not severe, 2= Less severe, 3= Neither Severe nor very severe, 4= Severe and 5= Very severe.Respondents who were made up of heads of households and tenants were assisted by technical experts in ranking the severity of the symptoms, hence, though expressing a lay person's opinion on the symptoms, the results on the severity of symptoms could be said to be varied.The checklist in Table 1, containing symptoms of dampness collected from the literature and modified to suit conditions in Ghana was pre-tested by trained assessors using 50 buildings and used for the study (Burns, 2010;Safeguard Europe Limited, SEL, 2007).In order to identify the most dominant type (lead source) of dampness, the trained assessors used the checklist in Table 1.Where N = the total population size; e= the standard error of sampling distribution assumed to be 0.013 and n is the sample size.Proportionate or quota sampling technique was used to select the sample size for each location as follows: Sekondi-Takoradi (517 buildings), Axim (56 buildings), Cape Coast (143 buildings), Accra (2738 buildings), Ho (143 buildings), Koforidua (153 buildings), Kumasi (1,406 buildings) Sunyani (117 buildings), Tamale (330 buildings), Bolgatanga (82 buildings) and Wa (115 buildings).The convenience purposive sampling approach was then used to select the residential buildings within each location (representing a cross section of buildings in the four climatic regions of Ghana).In all, 1% of the buildings (56 out of 5,800) was selected from the South Western Equatorial, 61% (3,541 out of 5,800) were selected from the Dry Equatorial, 29% (1,689 out of 5,800) were selected from the Wet Semi Equatorial and 9% (545 out of 5,800) were selected from the Tropical Continental Climatic Zones respectively.
A quantitative approach to data analysis was employed.Statistical Package for Social Scientists Version 16 (SPSS V 16) was used to analyze the data by means of frequencies and severity index.The severity index analysis (Idrus, 2011) uses weighted percentage scores to compare the relative importance of the criteria under study.The frequency analysis was first carried out to determine the frequency of responses which were then used to calculate severity indices (Idrus et al., 2011): Xi= Variable expressing the frequency of the response for i; i = 1, 2, 3, 4 and 5; X1= Frequency of the 'not severe' response and corresponding to a1= 1; X2= Frequency of the 'less severe' response and corresponding to a2=2; X3= Frequency of the 'neither severe nor very severe' response and corresponding to a3=3; X4=Frequency of the 'severe' response and corresponding to a4=4; X5=Frequency of the 'very severe' response and corresponding to a5=5.The results (Table 2) further show that in the South Western Equatorial climatic zone, 89% of the walls of buildings were constructed with sandcrete blocks and only 11% were constructed with earth.In the Dry Equatorial climatic zone, 94% of the walls of buildings surveyed were constructed with sandcrete blocks, 3% were constructed with earth and 3% were constructed with concrete.In the Wet Semi Equatorial climatic zone, the walls of buildings were constructed with concrete, earth, burnt bricks and sandcrete blocks.However, sandcrete blocks gained more usage as 83% of the outer walls were constructed with sandcrete blocks in this zone.In the Tropical continental climatic zone, 66% of the walls of buildings were constructed with earth.The results show that the outer walls of buildings surveyed in the four climatic zones of Ghana were mostly constructed with sandcrete blocks and earth, though concrete and burnt bricks were used in minor cases.This confirms that the outer walls of buildings in Ghana are constructed of sandcrete blocks, earth, concrete and burnt bricks (GSS, 2005).

Severity of Symptoms Associated with Dampness
The results (Table 3) show that 'mold growth (on cold surfaces, windows, etc)' is the most severe symptom of dampness (with SI of 90%) associated with walls in the South Western Equatorial climatic zone and therefore ranked first on the list of symptoms.In the Tropical Continental climatic zone, 'dampness at the base of walls up to 1.5m in horizontal band is ranked first on the list (with SI of 84%) as the most severe symptom associated with dampness in the walls of buildings.Stains, especially in horizontal band are ranked first (with SI of 97%) on the list of symptoms as the most severe symptom associated with dampness in the walls of buildings in the Wet Semi Equatorial climatic zone.In the Dry Equatorial climatic zone, 'surface efflorescence just above skirting/floor' is the most severe symptom (with SI of 89%) and therefore ranked first on the list of symptoms associated with dampness.The results show that each climatic zone has a unique symptom associated with walls of buildings.This is a situation likely to be caused by the differences in climatic conditions of each zone.For instance, mold growth highly associated with buildings in the South Western Equatorial climatic zone does not require the presence of standing water: it can occur when high relative humidity or the hygroscopic properties of building surfaces allow sufficient moisture to accumulate (www.epa.gov/laq/largebldgs/).Also, studies have shown that moisture levels within buildings are often higher than outdoors.The high indoor moisture levels result from the generation of warm moist air by domestic activities such as cooking, bathing/showering, clothes drying, high occupancy, etc.These are all factors which contribute to the raising of the indoor relative humidity.An increase in the Relative humidity increases the dew point temperature for the same air temperature.This will increase the risk of condensation should the water vapour come into contact with a surface below dew point (Australian Building Codes Board, ABCB, 2011).In the South Western Equatorial climatic zone, average monthly relative humidity levels (based on figures recorded each day at 12 noon) are highest as compared to the other climatic zones and range between 75-80%, a possible reason for walls being affected by mold growth in this zone.Tropical climates typically have high outdoor temperatures combined with high relative humidity and this result in high outdoor vapour pressure.This creates a slight inward vapour flow.For an air-conditioned building in a Tropical climate the indoor vapour pressure is reduced as both the indoor temperature and humidity is reduced.This results in a large vapour pressure difference, creating a much greater inward vapour flow (ABCB, 2011).Majority of the buildings which were surveyed in the South Western Equatorial Climatic zone had no air conditioning systems but had high occupancy rates, hence moisture generation activities was greater.It was realized from the study that temperature differences between rooms and between the interior and exterior had little contribution to the problem of condensation which created the mould growth in this climatic zone.
Cyclic wetting and drying brought about by seasonal changes is an important driver of salt attack or efflorescence in walls of buildings (Young, 2008).Changes in the relative humidity of a location can cause efflorescence to occur (Young, 2008).Surface efflorescence in walls is caused by rapid evaporation of water from wall surfaces leaving behind salt crystals (Young, 2008).As the Dry Equatorial Climatic zone is characterized by drying, there is that tendency of rapid evaporation of moisture from walls of buildings in this zone which could lead to the formation of salt bands on the surfaces of walls.One of the reasons why the surface efflorescence is the most severe symptom of dampness associated with buildings in this climatic zone.Though surface efflorescence was pronounced in buildings in the Dry Equatorial Climatic zone, buildings located within www.ccsen the other c manufactu coastal env high humi occupants, when expo The results of walls up dampness mold grow dampness 1999).

Identif
recorded the enormity of the problem(WHO, 2009;

Table 1 .
Symptoms associated with rising damp, surface condensation and water penetration Houses located in the major towns in the four main climatic regions were considered in the survey.According to the Ghana Statistical Service (2005), the number of buildings located in each town are as follows: Sekondi-Takoradi in the Western region (with 24,817 buildings), Axim in the Western region (with

Table 2 .
Table2shows the characteristics of the buildings surveyed in the four climatic zones in Ghana.The results show that 71% of the respondents interviewed in the South Western Equatorial Zone, 77% of the respondents interviewed in the Dry Equatorial Climatic Zone and 56% of the respondents in the Wet Semi Equatorial Climate Zone live in detached buildings.In the Tropical Continental Climatic Zone, 62% of the respondents live in compound houses.This confirms that compound and detached buildings are the major types of buildings occupied by people in Ghana(GSS, 2005).Characteristics of buildings surveyed

Table 3 .
Severity of symptoms associated with dampness in buildings