— Quality of material issues have been a significant source of concer n since the dawn of recorded history. Building materials are essential and should be performed according to standar d specifications because they cover around 60% of the proje ct cost. Prior to project construction, specific codes, standards, and specifications should be available. Using all required materials does not gu arantee a sound building appearance or function. Even with suitable ma terials, workmanship, and supervision, unexpected output can affec t a building. Quality workmanship is a comprehensive approach to bolstering building durability, serviceability, and safety. The stud y evaluated Ambo University's building construction materials and q uality. Convenience and quota sampling techniques were colle cted from all contractors and consultants involved in building c onstruction via questionnaires and interviews. A comprehensive liter ature review identified 15 major factors affecting building construction materials quality and workmanship, and respondents ranked t hem in the order of importance. Defects in existing buildings and ong oing projects had observed due to non-compliance with constru ction materials and workmanship based on specifications and standards. The re sults indicated that Ambo University building has no defect- free structure, including the degree and type of defects var y. A 94% of the studied buildings had moisture leakage, plastering defects, paint peeling, and cracks. Hence, the consultants and Ambo Un iversity project representatives should adhere with the standard specifications, and must exercise their profession according to the e thical code of conduct. All of these, it will play a vital role in the success of construction projects. Keywords —Building Projects, Contract Documents, Materials, Workmanship, Quality Control Implementation, Specifications, Standards.  I. INTRODUCTION Quality control is the process of comparing actual performance to go als and determining corrective action. It is the process that monitors specific project results to ensure they meet standards and id entifies ways to improve performance. It is an issue of attention in construction work due to problems associated with the project m ethods and techniques [ 1]. To meet the required standards, there should be clear drawings and specifications. Building construction uses resources such as labor, materials, and machinery . Building materials are vital in today's technologically advanced world. Their primary use is in construction, but t hey are essential in all fields of engineering. Also, the building materials industry is vital to our national economy because its outpu t determines the speed and quality of construction. Material surpluses may occur due to engineering, procurement, and field material management deficiencies [ 2-4, 18 ]. Approximately 90% of project failures are due to poor communication , inadequate checks and controls, and a lack of technical expertise. Examining the defects within the project site improves the w ork quality and reduces costs. Many projects suffer from poor maintenance and inefficient material usage. Most defects and failures in building structures are caused by inferior quality. Out of all structures, public buildings are the most prone to substandard construction. Incorrect compaction techniques, reinforcement issues, and other failures occur due to oversight by the concer ned organization [ 5, 6, 19 ]. Quality control of construction materials is now an important issue in con struction projects. The management system and application ensure the right quality and quantity of materials and installed equipm ent are specified promptly, obtained at a reasonable cost, and available when needed. It is widely acknowledged that constr uction material management involves the integrated coordination of material takeoff, purchase, and disposal. Incorr ect management of these functions can lead to material shortages, surpluses, and cash flow issues. Construction material sho rtages cause costly labor delays. Weakness, durability, and appearance are the results of poor material quality and workmanship [ 7]. Implementation means putting into practice a methodology, plan, or design . An action plan that follows an order or structure to achieve a goal [ 8, 9]. Using all required materials does not guarantee a sound building appearance or function. Even with suitable materials, workmanship, and supervision, the unexpected can affect a building. It may occur years after construction. So regular inspection and maintenance will be required. Materials account for roughly 60% of project costs. Because materials account for a large portion of the project's cost, improving material ma nagement and preventing problems will improve the overall building construction [ 2, 10 ]. Various studies show ed that most Ethiopian construction companies lack quality control programs, resulting in substandard projects. Universities are rapidly expanding in Ethiopia. They have po or-quality buildings and even under-construction projects. Ambo University is one of those universities. The research helped identif y issues with building projects and their quality to https://doi.org/10.37896/jxu15.8/013 138Journal of Xidian University VOLUME 15, ISSUE 8, 2021ISSN No:1001-2400 http://xadzkjdx.cn/ improve building projects at Ambo University. Quality control of constru ction materials is now an essential issue in the study area and entire Ethiopia. Poor material quality and workmanship lead to loss of money, time, s trength, durability, and appearance [ 7, 11, 19 ]. Ambo University's buildings are in poor condition, and the university loses mo ney on maintenance. Some buildings' functionality is also lacking. Ambo University has four campuses: Main Campus, Awaro Ca mpus, Guder Campus, and Woliso Campus. Many buildings with various functions such as administration, classrooms , dormitories, libraries, teaching, and referral hospitals have been built or are about to complete on these campuses. Many building defects are visible on buildings constructed with inferior materials and workmanship. It evaluated selected Ambo University buildings' materials quality control and workmanship and the factors affecting materials quality. The study focused on doing the following objectives: (1) to identify fac tors affecting building construction materials quality and building workmanship in Ambo University building projects; (2 ) to assess the status of Ambo University buildings based on their construction materials and workmanship by using observations, desk studies, and interviews; and, (3) to suggest possible mitigations for the practical problems and recommend basic requirements for th e present and future building project works. II. RESEARCH METHODOLOGY A. Study Area The study was conducted at Ambo University Buildings, with campuses as follows: Main Campus, Awaro Campus, Guder Campus, and Woliso Campus, which are located in Ambo, Ambo, Guder , and Woliso towns, respectively. Fig. 1 Location map (Source: Google map 2021) B. Research Design Following a literature review, major factors affecting materials quality and workmanship were identified. Buildings at Ambo University are classified based on their functions: Administration, dormitor ies, libraries, Teaching and Referral hospitals, Others (Laboratories, Offices, Clinics, etc.). The study evaluated the materials qualit y control and workmanship of selected G+2 and higher university buildings. Existing and planned G+2 buildings were v isually inspected in details. Restrictions on the use of contract documents are not imposed. A comprehensive review of previously published works, internet data, and other related files was organized to assess the building materials quality control implementation and workmanship on the selected buildings. Questionnaires and interview instruments are used to collect data. Across Ambo University's four ca mpuses, convenience sampling and quota sampling were used to determine the required sample size and type. Likewise, the research er used a quantitative approach to analyze the questionnaire data. C. The population of the Study and Sample Size Selection As a case study, the study utilized respondents and buildings G+2 and above in Ambo University. The sample size was chosen using convenience sampling and quota sampling techniques based on acces sibility and specific characteristics. All Ambo University contractors and consultants had been selected based on accessibilit y. In the particular character of building height, G+2 and above buildings were chosen because they account ed for over 90% of all buildings. Only 26 contractors and 3 consultan ts were available to respond during the research period. Buildings G+2 and above were studied for material quality control and workmanship. Nine others (mixed purpose buildings) were investigated , along with 30 dormitories. The samples were instrumental in gathering all necessary data. https://doi.org/10.37896/jxu15.8/013 139Journal of Xidian University VOLUME 15, ISSUE 8, 2021ISSN No:1001-2400 http://xadzkjdx.cn/ TABLE I GENERAL PROFILE OF THE ASSESSED PROJECTS No. Project Name Height No. of Bldgs. Status Location EXISTING BUILDINGS 1 Dormitories ≥G+2 30 Completed All Campuses 2 Classrooms and Seminar ≥G+2 16 Completed All Campuses 3 Libraries G+3 5 Completed All Campuses 4 Laboratories G+2 8 Completed All Campuses 5 Others (mixed purpose buildings) ≥G+2 9 Completed All Campuses ON-PROGRESS BUILDINGS 1 AU Referral and Teaching Hospital 2B+G+5 1 On-progress Main Campus 2 Classroom, Lab, Office (3 wings) G+5 1 On-progress Main Campus 3 President Office G+6 1 On-progress Main Campus 4 Main Administration, Awaro (5 Wings) G+3 1 On-progress Awaro Campus 5 Classroom and Clinic G+4 2 On-progress Guder Campus 6 Classroom, lab, Office (3 wings) G+5 1 On-progress Woliso Campus TABLE II GENERAL PROFILE OF CONTRACTORS AND CONSULTANTS CONTRACTORS S. No. Company Name Projects Location 1 TNT Trading and Construction Referral Hospital Main Campus Main Administration Awaro Campus 2 Flint Stone Engineering Staff Residence Awaro Campus Staff Residence Guder President Office Main Campus 3 Yotek AU Expansion, Ambo & Guder Classroom, dormitory, Office 4 MCG Construction Plc. Classroom, Lab, Office Main Campus 5 Tekle Birhan Ambaye Classroom, dormitory, Office Main Campus 6 Libu Kifle BC Dormitory, classroom, Clinic Awaro, Guder 7 Samket Engineering Classroom, Lab, Office Woliso Campus 8 Antneh Mohammed BC Dormitory, Seminar, classroom Awaro Campus 9 Wayuma Gemessa BC Dormitory 10 Atinafu Ashine BC Dormitory Awaro Campus 11 Icon Construction Plc Veterinary Clinic Guder Campus 12 Tolif Construction Daycare School Main Campus 13 Barecha Fitta BC Library Awaro Campus 14 Tesfaye Abebe BC Dormitory Woliso Campus 15 Asnake Teshome BC Dormitory Woliso Campus 17 Horata Engineering Dormitory, Lecture Hall Awaro Campus 18 Jemal Fanta BC Auditorium, Dormitory, Seminar Guder Campus 19 Guta Lemecha BC Dormitory Guder Campus 20 Justice Construction PLC Dormitory Awaro Campus 21 Andersa Jote Referral Hospital and main campus maintenance Ambo 22 Fanta Negash B.C Seminar, classroom Awaro Campus https://doi.org/10.37896/jxu15.8/013 140Journal of Xidian University VOLUME 15, ISSUE 8, 2021ISSN No:1001-2400 http://xadzkjdx.cn/ 23 Bios Construction PLC Lecturer hall, DAB Awaro Campus 24 Ansif Seyum BC Laboratory Guder Campus 25 Rift Valley Construction Dormitory Guder Campus 26 Lemma Edae BC Seminar, classroom Awaro Campus CONSULTANTS 1 MH Engineering 2 CDSWC 3 K2N 4 BED 5 Project Administration Team (AU) D. Reliability Test According to [ 12], any measurement-based research must consider reliability. Reliability concer ns whether the data collection and analysis procedures produce consistent results and whether oth ers can make similar observations and draw the same conclusions from the same raw data. That is, data collection procedures can be repeated with the same results. Lee Cronb ach developed Cronbach's Alpha in 1951 to assess a test's internal consistenc y; it is always expected to fall between 0 and 1. The measurement system was created to measure a specific concept by asking a group of people a series of questions (items). Inter nal consistency is defined as the extent to which all questions positively contribu te to measuring the same concept or construct [ 12, 13, 14 ]. Besides, internal consistency is expressed as the proportion of the test varian ce attributable to a group of items, which measures the reliability coefficient alpha [ 13]. ∝ = 𝐼 𝐼−1(1 −∑ 𝜎𝐼2 𝐼 𝑖=1 𝜎𝑋2) (1) Where: 𝐼 = Number of Items 𝜎𝐼2 = variant items 𝜎𝑋2 = total score variant A high value of the Cronbach’s alpha implies a higher internal consistency of the construct 𝜎𝑋2. The higher the coefficient, the stronger the linear relationship of the items is correlated and the higher the internal consistency cited by [ 13, 14 ]. On the other hand, [ 15] provide the following rules o f thumb: “_ > .9 – Excellent, _ > .8 – Good, _ > .7 – Acceptable, _ > .6 – Questionable, _ > .5 – Poor, and _ < .5 – Unacceptable”. While increasing alpha depends on the number of items in the scale, there are diminishing returns [ 16]. Because Cronbach's alpha coefficient is the most widely used objective measu re of reliability, the internal consistency of the scale of data reliability (data collected via a questionnaire) was checked before the analysis of the study. E. Validity Test [12] defines validity as the degree to which the instrument measures what the researchers want to measure. Validity is the most important criterion that indicates how well an instrument measures what it is su pposed to measure. It was verified the content validity of the research by examining the questions and measurement sca les. A pilot test of the questionnaire was given to some respondents. Checking the clarity, length, structure, and wording o f the questions was also done. As a result of the test, the researcher was able to revise. F. Data Analysis The relative index methods were used to analyze the questionnaire data. Using t he frequency analysis, the relative index ranked the importance and practicability of each performance measure using the given formula below [ 14, 17 ].    5 4 3 2 5 4 3 25 4 3 2 5n n n n n RII n n n n n         (2) Where: RII = represents Relative Importance Index n5, n4, n3, n2 & n= represents number of indicators of answer. Computation with the Relative Importance Index (RII) provides a value b etween 0.2 and 1.0. The 0.2 value represents the lowest strength, and the 1.0 value the highest strength value. The d ata obtained from questionnaire surveys and desk studies are qualitatively and quantitatively analyzed, evaluated, and interpreted. https://doi.org/10.37896/jxu15.8/013 141Journal of Xidian University VOLUME 15, ISSUE 8, 2021ISSN No:1001-2400 http://xadzkjdx.cn/ III. RESULTS AND DISCUSSI ON A. Data from a questionnaire, factors affecting building construction materials and w orkmanship The contractors, consultants, and customers have been provided with a well-structured questionnaire and distributed it. All consultants and contractors involved in AU Buildings have been taken into account. In the course of the research, AU construction was participated by 26 contractors and 3 consultants. Ninety questionnaires were distributed, and from these, only 77 questionnaires were returned (26x3=78 contractors, 3x3=9 consultants, and 1x3=3 clients). The questionnaire validity is determined on the basis that the replies as adequate. i.e., questionnaires are deemed invalid without replies and partial replies. 7 1 of the 77 questionnaires received were therefore considered valid, showing a response rate of 78.9%. TABLE III QUESTIONNAIRE RESPONSE RATE Description Respondents %) Total (%) Contractors Consultants Client Questionnaires distributed, (A) 78 9 3 90 Questionnaires retrieved 69 7 1 77 Valid responses, (B) 63 7 1 71 Response rate (valid), (C) = (B/A)*100 80.80% 77.80% 33.30% 78.90% Nineteen site engineers, seventy office engineers, fourteen project manag ers, two architects, eight resident engineers, and eleven senior engineers have been observed from the returned questions among the total respondents. TABLE IV RESPONDENTS WORKING POSITION Respondents Working Position S. No Position No. Percentage (%) 1 Site Engineer 19 26.80 2 Office Engineer 17 23.90 3 Project Manager 14 19.70 4 Architect 2 2.80 5 Resident Engineer 8 11.30 6 Senior Engineer 11 15.50 There were 26 contractors, 2 private consultants, 1 governmental and private p artner consultant, and 1 state employer concerning company type and ownership (client). The table below summarizes the working experience of companies in the Ethiopian construction and building industries in different years. TABLE V WORK EXPERIENCE OF ORGANIZATIONS Work Experience of Organizations In the Ethiopian construction industry (in a year) In the building construction sector (in a year) Experience (No. of year s) Organizations by: Experience in year Organizations by: No. Percentage (%) No. Percentage (%) 0 – 5 years 4 13.30 0 – 5 years 4 13.30 6 –10 years 9 30.00 6 –10 years 9 30.00 11 – 15 years 8 26.70 11 – 15 years 8 26.70 More than 15 years 9 30.00 More than 15 years 9 30.00 https://doi.org/10.37896/jxu15.8/013 142Journal of Xidian University VOLUME 15, ISSUE 8, 2021ISSN No:1001-2400 http://xadzkjdx.cn/ Table VI summarizes the work experience of the individual respondents in the Ethiopian construction industry and the building construction sector by years separately. TABLE VI WORK EXPERIENCE OF INDIVIDUAL RESPONDENTS Work Experience of Individual Respondents In the Ethiopian construction industry (in a year) In the building construction sector (in a year) Experience (No. of years) Respondents by: Experience in year Respondents by: No. Percentage (%) No. Percentage (%) 0 – 5 years 12 16.90 0 – 5 years 17 23.90 6 –10 years 35 49.30 6 –10 years 34 47.90 11 – 15 years 13 18.30 11 – 15 years 11 15.50 More than 15 years 11 15.50 More than 15 years 9 12.70 TABLE VII ORGANIZATIONS PRACTICE MATERIALS QUALITY CONTROL AND WORKM ANSHIP Phrases that best define quality Self-performance judgment on constructed buildings Phrases that best define quality Responses Self-performance judgment Responses Frequency No. In percent (%) Expensive materials 7 Excellent 5 7.04 Appearance/ Aesthetics 31 Very good 58 81.70 Increased profit 24 Good 8 11.26 Customer’s satisfaction 54 Satisfactory 0 0 Meeting specification requirement 66 Poor 0 0 Organization quality management system Degree of compliance with BOQ or Specification Organization quality management system Responses (firms) Degree of compliance with BOQ or spec Responses No. In percent (%) No. In percent (%) ISO 4 13.33 More than 90 % 67 94.36 TQM 11 36.67 80 - 90% 4 5.64 QA/QC 15 50.00 70 - 80% 0 0 less than 70% 0 0 Most contractors and consultants use many mechanisms to monitor and ver ify compliance with technical specifications in the construction of projects. The testing and examination shall check 93% of the materials reported on the questionnaire, and the remaining seven percent was checked according to the respondents using t he manufacturer's catalog. B. Major variables that could affect building construction materials quality and workman ship of the project Internal consistency of data describes the extent to which all items in an instru ment measure the same concept. The internal consistency of the collected data was first tested using the Cronbach's alp ha coefficient formula described under the reliability test. Following this, the Cronbach's coefficient for contractors and consu ltants was 0.812 and 0.753, respectively. As a result, the Cronbach's coefficient values for all parties are above 0.70, proving v alidity. Using this evidence, all survey data were analyzed. After verifying the survey data's reliability, the relative importance ind ex method was used to rank material and constructio n quality factors. A comprehensive literature review identified fifteen major factors affecting building construction materials' quality and workmanship. A well-structured questionnaire was created to collect prof essional views and experiences from the respondents on these significant factors. https://doi.org/10.37896/jxu15.8/013 143Journal of Xidian University VOLUME 15, ISSUE 8, 2021ISSN No:1001-2400 http://xadzkjdx.cn/ TABLE VIII MAIN FACTORS AFFECTING MATERIALS QUALITY AND WORKMANSHIP No. Main factors affecting materials quality control and workmanship Degree of Importance Total RII Rank 5 4 3 2 1 1 Applicability of Building Regulations 31 19 21 0 0 298 0.84 4 2 Factors related to Design 28 36 7 0 0 305 0.86 2 3 Factors related to Specification 22 41 7 1 0 297 0.84 4 4 Factors related to Management 37 28 6 0 0 315 0.89 1 5 Factors related to Nature of Materials 33 29 6 2 1 304 0.86 2 6 Factors related to Labors 28 28 12 3 0 294 0.83 5 7 Factors related to Site Access 9 27 32 2 1 254 0.72 8 8 Factors related to Financial 27 32 11 1 0 302 0.85 3 9 Factors related to Site staffs 36 26 5 4 0 307 0.86 2 10 Factors related to Weather conditions 24 25 16 6 0 280 0.79 6 11 Factors related to Technical issues 6 14 45 2 4 229 0.65 10 12 Factors related to Materials Testing and Inspection 38 27 5 1 0 315 0.89 1 13 Factors related to Project Nature 21 18 31 0 1 271 0.76 7 14 Factors related to Equipment 9 23 35 3 1 249 0.7 9 15 Factors related to Knowledge of Implementing Rules & Regulations of the Government Procurement Law 7 14 13 31 6 198 0.56 11 As shown in Table V III, the respondents identified and ranked the main variables affecting building construction materials' quality and workmanship. The respondents ranked the factors related to management , materials testing, and inspection with RII = 0.89. Project management is critical to achieving quality pr ojects in all phases. Material testing and inspection are important activities that directly check material's compliance with specifications and standards. The design, materials, and site staff variables were ranked second with an RII of 0.86. As the found ation for subsequent construction activities, design influences both material, and workmanship quality. The material used directly affects th e project's quality. The commitment of the site staff is critical to the project's quality control and workmanship. Financial factors are ranked third with RII = 0.85, followed by Applicability of Building Regulations and Specification Factors with RII = 0. 84. The remaining variables have RII of 0.83, 0.79, 0.76, 0.72, 0.70, 0.65, and 0.56. 1) Factors related to management It includes good project managers, foremen, superintendents, and others. The project manager's knowledge of materials and workmanship impacts the overall project. Consultant full-time involve ment and Strict and professional control of all project workers rank first and second with RII of 0.92 and 0.90, resp ectively. Qualified projects result from competent construction consultants who are excellent planners with strong material specification ski lls. All workers on the project should be qualified and meet quality standards. A single unqualified worker can derail an entire project. Contractor attention on materials quality and workmanship are ranked third by respondents with RII = 0.89. Th e Contractor will be doing the work on-site, so quality materials and workmanship are important. The professionalism of managers and coo rdinators and Consultant-Contractor Collaboration rank fourth and fifth with RII of 0.84 and 0.83. Communication wi thin an organization and on-site is to influence the actions/behaviors of others or to exchange or request information during a construction pr oject. TABLE IX FACTORS RELATED TO MANAGEMENT No. Sub-factors related to management Degree of importance Total RII Rank 5 4 3 2 1 1 Cooperation between consultant and Contractor 29 24 18 0 0 295 0.83 5 2 Consultant full-time involvement 47 21 3 0 0 328 0.92 1 3 Contractor attention on materials quality 41 23 6 1 0 317 0.89 3 4 Contractor attention on workmanship 39 27 4 1 0 317 0.89 3 https://doi.org/10.37896/jxu15.8/013 144Journal of Xidian University VOLUME 15, ISSUE 8, 2021ISSN No:1001-2400 http://xadzkjdx.cn/ 5 Strict and professional control of all workers on the project 45 18 8 0 0 321 0.9 2 6 Professional capability of respective managers and coordinators 29 28 13 1 0 298 0.84 4 2) Factors related to Materials Testing and Inspection Material testing and inspection are vital in quality control. All materials must pass tests and inspections to meet specifications. PILING INSPECTIONS: vibration monitoring, ground-penetrating radar (GPR), pre and post-construction surveys, and settlement plate. Testing frequencies and tolerances, daily production records, inspection, and verification are sub-factors with RII values of 0.84. Defects or non-compliance should be reported. C ertified technician testing was second with 0.82 RII. Certified technicians should perform all required tests. With an RII of 0.81, resp ondents ranked having an on-site lab third. The remaining materials testing and inspection issues have RII of 0.80, 0.77, and 0.74. Construction and material quality control rely on them. TABLE X FACTORS RELATED TO MATERIALS TESTING AND INSPECTION S. No Sub-factors related to Materials Testing and Inspection Degree of importance Total RII Rank 5 4 3 2 1 1 Availability of lab at the site 23 27 21 0 0 286 0.81 3 2 Independent certification by an approved body 19 24 18 8 2 263 0.74 6 3 Sampling and testing procedures 24 22 18 6 1 275 0.77 5 4 Testing frequencies and tolerances 35 21 11 3 1 299 0.84 1 5 Daily production records 31 23 17 0 0 298 0.84 1 6 Testing by certified technicians 31 22 14 3 1 292 0.82 2 7 Inspection and Verification 35 21 11 2 2 298 0.84 1 8 Calibration of Instruments used for testing 26 22 21 2 0 285 0.8 4 3) Factors related to design Design is vital in construction projects as it serves as a master requirement plan and specifications. Non-functional design can impede activities, detract from the quality, and raise costs to unacceptably high levels. Like Newton's third law of motion, every design decision/consideration has consequences. During the design phase, all drawings should be detailed, consistent, and complete. With RIIs of 0.82 and 0.80, respondents ranked drawing preparation first, followed by design document completeness and consistency. Design conformance to codes and standards and practice an d accuracy of the bill of quantity also gain 0.74 a nd 0.70 RII. Materials and workmanship quality control are essential sub-factors of the design variable. TABLE XI FACTORS RELATED TO DESIGN S. No Sub-factors related to design Degree of importance Total RII Rank 5 4 3 2 1 1 Completeness and consistency of design documents 25 28 12 4 2 283 0.8 2 2 Drawings are prepared in details 31 23 11 6 0 292 0.82 1 3 Design conformance to codes and standards 18 27 16 8 2 264 0.74 3 4 Bill of quantity is detailed and accurate 14 18 29 8 2 247 0.7 4 4) Factors related to Nature of Materials The respondents ranked eight important issues under the nature of materials based on their importance. It is the first important sub-factor that can affect the quality and workmanship of building projects. The RII is 0.86. To be environmentally friendly, construction materials must be highly durable and sourced locally. Str ength and durability, Availability of materials as approved plan, Attack resistance (e.g., fire, heat, water, chemicals, weather action), Flexib ility of materials on work, and Availability of material suppliers also have RII values of 0.85, 0.81, 0.79, 0.76 , 0.68, and 0.66. The respondents rank them according to their https://doi.org/10.37896/jxu15.8/013 145Journal of Xidian University VOLUME 15, ISSUE 8, 2021ISSN No:1001-2400 http://xadzkjdx.cn/ importance for quality control and workmanship. All of the issues me ntioned above play a role in the execution of building projects. TABLE XII FACTORS RELATED TO NATURE OF MATERIALS S. No Sub-factors related to Nature of Materials Degree of importance Total RII Rank 5 4 3 2 1 1 Availability of materials as approved plan 29 25 11 4 2 288 0.81 3 2 Availability of material suppliers 13 16 27 9 6 234 0.66 7 3 Sustainability of materials 34 24 12 1 0 304 0.86 1 4 storage and handling system 33 27 10 1 0 305 0.86 1 5 Flexibility of material on work 17 28 22 3 1 270 0.76 5 6 Attack resistance (e.g. fire, heat, water, chemicals, weather action) 23 22 24 2 0 279 0.79 4 7 Strength and durability 31 27 13 0 0 302 0.85 2 8 Affordability of materials 12 19 28 10 2 242 0.68 6 5) Factors related to Site staffs Construction firms have their own organizational structure. Because each proj ect has its own context and content, roles and responsibilities will vary greatly. The involvement of workers is critical. It is ranked 1 –6 in terms of supervisory skill and experience, contractor skill and experience, supervisory dedication (continu ous follow-up work), and supervisory understanding of contract administration. The supervisory and Contractor staffs' R IIs are 0.90 and 0.85, respectively. The third was work commitment (constant supervision) (RII 0.84). TABLE XIII FACTORS RELATED TO SITE STAFF S. No Sub-factors related to Site Staffs Degree of importance Total RII Rank 5 4 3 2 1 1 Cooperation between Supervision and Contractor’s staffs 26 32 13 0 0 297 0.84 4 2 Understanding of contract administration by Supervision 23 28 17 3 0 284 0.8 6 3 Skill and experience of Supervision staff 43 22 5 1 0 320 0.9 1 4 Skill and experience of Contractor's staff 32 26 13 0 0 303 0.85 2 5 Dedication of supervision staffs (continuous follow up of work) 35 19 14 2 1 298 0.84 3 6 Dedication of contractor staff (continuous follow up of work) 31 18 18 4 0 289 0.81 5 6) Factors related to Financial In Table XIV, payment delay ranked first with 0.86 RII. Then com es a 0.82 RII material price increase. One of the significant challenges facing the construction industry is rising material costs. In Ethiopia, the construction sector is burdened by rising construction material and input costs and domestic and global inflation. Overtime cost, contractor cash flow, and labor cost escalation ranked third, fourth, and fifth with RII of 0.75, 0.74, an d 0.70. Project delays result in cost overruns, and labor cost increases harm the project. TABLE XIV FACTORS RELATED TO FINANCIAL S. No Sub-factors related to financial Degree of importance Total RII Rank 5 4 3 2 1 1 Escalation of materials price 31 23 12 3 2 291 0.82 2 2 Escalation of labor cost 13 27 16 12 3 248 0.7 5 3 The amount of Contractor's cash flow 17 26 18 10 0 263 0.74 4 4 Delay of payments 36 22 11 2 0 305 0.86 1 5 Project overtime cost 19 26 19 5 2 268 0.75 3 https://doi.org/10.37896/jxu15.8/013 146Journal of Xidian University VOLUME 15, ISSUE 8, 2021ISSN No:1001-2400 http://xadzkjdx.cn/ 7) Factors related to Applicability of Building Regulations Building codes and standards, both international and local, are critical to successf ul projects. They are designed to ensure that the construction policies set out in the relevant legislation are followed and to establis h harmonized construction laws . TQM, QA, and QC applications had 0.86 RII. Applicability of BOQ (Contract), Specifications, EBCS, and ISO ranked second, third, fourth, and fifth with RII values of 0.78, 0.77, 0.69 , and 0.64. Contract Documents are the written documents that define the roles, responsibilities, and "Work" under the construction contract and are leg ally binding on the parties. TABLE XV FACTORS RELATED TO APPLICABILITY OF BUILDING REGULATIONS S. No Sub-factors related to Applicability of Building Regulations Degree of importance Total RII Rank 5 4 3 2 1 1 Applicability of ISO 6 13 44 5 3 227 0.64 5 2 Applicability of EBCS 17 13 27 13 1 245 0.69 4 3 Applicability of Specifications 24 22 19 4 2 275 0.77 3 4 Applicability of BOQ (Contract) 23 28 9 11 0 276 0.78 2 5 TQM, QA, QC applications 37 24 5 5 0 306 0.86 1 8) Factors related to specification Specifications are part of the contract documents that govern the project's per formance. Because specifications influence all aspects of a construction project, clear specifications and a shared understan ding of their intent by all parties lead to better projects. To avoid change orders and other misunderstandings, all materials and w ork must be specified accurately. Preparation of specifications for all materials ranked first with an RII of 0.84. It is followed by the preparation of Separate specifications other than BOQ, which has 0.80 of RII. The other sub-factors are Availability of full specification, Specification consistency with drawings, Specification for all necessary tests of materials and workmans hip, Change order (Addition, Subtraction, or alteration), and Mistakes in quantity survey are having 0.78, 0.78, 0.75, 0.6 8, 0.61 RII respectively. Generally, the specification document serves as the backbone of the entire project. TABLE XVI FACTORS RELATED TO SPECIFICATIONS S. No Sub-factors related to specification Degree of importance Total RII Rank 5 4 3 2 1 1 Availability of full specification 22 31 9 8 1 278 0.78 3 2 Specification for all materials and works 36 22 7 3 3 298 0.84 1 3 Specification consistency with drawings 25 20 19 7 0 276 0.78 3 4 Specification for all necessary tests of materials and workmanship 21 21 18 11 0 265 0.75 4 5 Separate specification other than BOQ 22 30 17 2 0 285 0.8 2 6 Change order (Addition, Subtraction, or alteration) 9 20 35 3 4 240 0.68 5 7 Mistakes in quantity survey 7 18 21 23 2 218 0.61 6 9) Factors related to labors Project managers must pursue efficient labor utilization. Those in charg e of quality and cost control of built facilities should constantly strive to improve labor productivity. The involvement of at least one chief worker in their respective work is ver y important to produce projects of required quality and pleasing workma nship. Labor communication skills and training or workshops are important sub-factors that can contribute to the project if implemented correctly. Proportional income is one of the motivational systems that could be used to improve labor productivity. Rec ruiting skilled and trained workers is required to complete a job professionally. Labor experience, involvement of at least one ch ief worker in respective works, and labor communication skills are ranked first to third with RII of 0.88, 0.86, and 0.84, respectively. The remaining issues are labor training, motivation, and income and wages, with RII values of 0.81, 0.74, and 0.64. Since workers perform all activities, most defects in construction projects are caused by human errors, specifically poor workmanship. https://doi.org/10.37896/jxu15.8/013 147Journal of Xidian University VOLUME 15, ISSUE 8, 2021ISSN No:1001-2400 http://xadzkjdx.cn/ TABLE XVII FACTORS RELATED TO LABORS S. No Sub-factors related to Labors Degree of importance Total RII Rank 5 4 3 2 1 1 Communication skills of labor 23 41 5 2 0 298 0.84 3 2 labors experience 41 19 9 1 1 311 0.88 1 3 Involvement of at least one chief worker in respective works 36 21 14 0 0 306 0.86 2 4 Motivation System 18 21 28 1 3 263 0.74 5 5 Training or workshop for labors 26 29 12 2 2 288 0.81 4 6 Income level and wages of labors 11 14 32 7 7 228 0.64 6 10) Factors related to Weather conditions Extreme weather can impact construction timelines and materials. Even in Eth iopia, where extreme weather is rare, construction can be complex, especially in the summer. Snow and ice can damage materials and machinery and pose safety risks to workers. The rainy season can affect the quality of construction m aterials and workmanship. Even if the remaining sub-factors aren't common, they affect building construction. That's why it came first. Its RII is 0.56 for humidity, 0.53 for Prevailing Wind, and 0.50 for out of Range Temperature. TABLE XVIII FACTORS RELATED TO WEATHER CONDITIONS S. No Sub-factors related to Weather Conditions Degree of importance Total RII Rank 5 4 3 2 1 1 Rainy season 10 15 29 14 3 228 0.64 1 2 Out of the range Temperature 3 12 19 22 15 179 0.5 4 3 Prevailing Wind 7 9 18 27 10 189 0.53 3 4 Humidity 9 14 19 11 18 198 0.56 2 11) Factors related to Project Nature The main issues listed under project nature are budget, duration, scope, s ite accessibility, and location. These are the major ones, but there may be others. Budgets for project construction are pre pared and approved prior to a defined period to achieve a given objective. Budgets should be set as early as possible, based on evidence, and be realistic. The size and accessibility of a project are important factors in material selection and workmanship. The pro ject budget was ranked first, followed by the project period (RII 0.79). The project's scope ranked third with an RII of 0.74, and its accessibility and location ranked fourth and fifth with RIIs of 0.68 and 0.65. TABLE XIX FACTORS RELATED TO THE PROJECT NAME S. No Sub-factors related to Project Nature Degree of importance Total RII Rank 5 4 3 2 1 1 Scope of the project 16 26 20 8 1 261 0.74 3 2 Location of the project 9 18 31 7 6 230 0.65 5 3 Site accessibility 10 22 29 7 3 242 0.68 4 4 Period of the project 25 23 17 4 2 276 0.78 2 5 Budget of the project 27 22 13 9 0 280 0.79 1 12) Factors related to Site Access All sub-factors listed under site access have an impact on materials and wo rkmanship quality. Materials should be stored in a planned manner and handled with care by all workers. Material handling inv olves the delivery, movement, storage, and control of materials and other products. It was followed by site distance from material suppliers (RII 0.67). Material delivery and supplier https://doi.org/10.37896/jxu15.8/013 148Journal of Xidian University VOLUME 15, ISSUE 8, 2021ISSN No:1001-2400 http://xadzkjdx.cn/ distance affect material quality. The other issues are working site cleanliness, site layout size (too small or too large to store and handle materials), and site suitability (to perform good quality workmansh ip), with RII of 0.64, 0.62, and 0.59, respectively. TABLE XX FACTORS RELATED TO SITE ACCESS S. No Sub-factors related to Site Access Degree of importance Total RII Rank 5 4 3 2 1 1 Cleanliness of the working site 9 13 35 11 3 227 0.64 3 2 Site layout or orderly for material storage/ handling 21 31 13 4 2 278 0.78 1 3 Size of site layout, i.e., too small or too large to store and handle materials 6 14 36 12 3 221 0.62 4 4 Site distance from material supplier’s 12 15 29 15 0 237 0.67 2 5 Suitability of site to perform good quality workmanship 8 7 33 21 2 211 0.59 5 13) Factors related to equipment The equipment management system impacts the project's quality and workmanship. Construction equipment can improve product quality, project efficiency, cost savings, profitability, and site safety. Choosing the right construction equipment and qualified operator is crucial. Equipment efficiency was identified as the most critical sub-factor, followed by operator experience and performance. The third and fourth important sub-factors are eq uipment technology, cost, and quality. Their RII values are 0.80, 0.75, 0.72, and 0.71, respectively. TABLE XXI FACTORS RELATED TO EQUIPMENT S. No Sub-factors related to equipment Degree of importance Total RII Rank 5 4 3 2 1 1 Equipment efficiency 24 29 13 5 0 285 0.8 1 2 Operator experience and performance 21 21 19 9 1 265 0.75 2 3 Quality of Equipment 12 27 22 7 3 251 0.71 4 4 Technology and cost of Equipment 15 23 25 6 2 255 0.72 3 14) Factors related to Technical issues The study's technical issues concern finishing works and related operatio ns. Each of the sub-factors discussed here has an RII of 0.72, 0.69, 0.61, and 0.56. These issues affect material quality, workmanship, and even building performance. Workability is the quality of being workable, practical capacity to succeed, and how easily the material can be operated in a required way. The more workable materials used, the more qualified the building project is o perated. The building's external and internal faces require pleasing materials, and they should be considered during design and construction. The final project's maintenance level, color, and texture were carefully considered. TABLE XXII FACTORS RELATED TO TECHNICAL ISSUES S. No Sub-factors related to Technical Issues Degree of importance Total RII Rank 5 4 3 2 1 1 Appearance and aesthetic value 13 27 13 14 4 244 0.69 2 2 Color and Texture 8 11 21 22 9 200 0.56 4 3 Maintenance level 8 13 29 16 5 216 0.61 3 4 Workability level 17 23 17 12 2 254 0.72 1 15) Factors related to Knowledge of Implementing Rules & Regulations of the Gove rnment Procurement Law Procurement management systems must adhere to government procuremen t laws. Defects The RIIs for the four issues discussed were 0.61, 0.56, 0.49, and 0.44. Poor materials and wor kmanship cause building defects. Most contracts require the https://doi.org/10.37896/jxu15.8/013 149Journal of Xidian University VOLUME 15, ISSUE 8, 2021ISSN No:1001-2400 http://xadzkjdx.cn/ Contractor to return to the site to remedy defects during the defects liability period. A Variation Order is a written change to the contract's original scope of work. Variations often lead to poor performance and workmanship. Building construction projects require controlling variation orders to perform well —negative slippage and contract termination impact project quality. TABLE XXIII FACTORS RELATED TO KNOWLEDGE OF IMPLEMENTING RULES & REGULATIONS OF THE GOVERNMENT PROCUREMENT LAW S.No Sub-factors related to Knowledge of Implementing Rules & Regulations of the Government Procurement Law Degree of importance Total RII Rank 5 4 3 2 1 1 Variation Orders (Change Order, Extra Work Order) 4 13 31 11 12 199 0.56 2 2 Negative Slippage 7 11 11 21 21 175 0.49 3 3 Defects Liability period 12 16 14 20 9 215 0.61 1 4 Termination of Contract 3 8 12 25 23 156 0.44 4 According to Cronbach's alpha analysis, Cronbach's coefficients for con tractors and consultants were 0.812 and 0.753, respectively. As a result, the Cronbach's coefficient values for all parties are above 0.70 , proving validity. So all survey data was analyzed. C. Analysis and discussion of data from case studies and desk studies 1) Existing (completed) buildings status analysis based on their materials quality con trol and workmanship Ambo University has many buildings with various functions on all cam puses. Buildings G+2 and above are examined for material quality and workmanship. Nine others (mixed purpose buildin gs) are investigated in addition to 30 dormitory buildings. All of these buildings have been visually inspected and identified with various flaws. It is determined that the causes of these defects are due to poor construction materials and workmanship. Table XXI V shows the major defects found in the buildings. Walls, ceilings, floors, doors, and windows had more visible and v aried defects. They were observed both inside and outside the buildings chosen for the study. According to the surveyed literature, many construction materials crack with age, expand and contractions, especially when exposed to moisture. Building cracks are cau sed by drying shrinkage, thermal movement, elastic deformation, creep, chemical reaction, foundation movement and settlement, and vegetation growth. TABLE XXIV MAJOR DEFECTS OBSERVED ON EXISTING BUILDINGS Observed Defects Frequency of buildings having defects C1 (30) C2 (16) C3 (5) C4 (8) C5 (9) Defects on foundations, column, beam and slab Settlement 14 4 1 3 3 Cracks on beams, columns, slabs 9 3 2 3 2 Defects on wall, ceiling, floors, doors, windows Cracks on HCB walls 24 16 5 8 7 Floors and walls moisture leakage 30 9 3 2 9 Water damage on ceilings, walls, or floors 23 11 3 5 9 Ceiling and wall joint separation 12 3 2 4 4 Defective floor, wall & external finish 30 16 5 8 9 Broken or loose tiles on floors or wall 15 13 2 3 6 Shrinkage cracks on plastering 22 16 5 8 9 Paint peeling on faces of walls, columns, and beams 30 16 5 8 9 Water seepage through windows and doors 18 5 0 6 4 Tiles missing grout/sealant 11 7 2 - 4 Plastering defects 30 16 5 8 9 Chipped or cracked tiles 16 7 2 - 5 Defects on doors and windows framing 23 16 3 8 5 Defects on roofs Poor roof slope 10 0 0 2 3 https://doi.org/10.37896/jxu15.8/013 150Journal of Xidian University VOLUME 15, ISSUE 8, 2021ISSN No:1001-2400 http://xadzkjdx.cn/ Improperly sized and sloped gutters 10 6 2 4 3 Some downpipes have damage 21 9 3 6 7 Damaged roof sheathing 6 3 0 2 1 Defects on sanitary systems Shower and toilet leaks 30 12 2 3 9 Poor sanitary pipes installation 30 12 2 3 9 Broken fixtures 30 16 5 6 9 Defects on electrical systems Lights not working to some areas 30 16 5 7 9 Broken fixtures 30 16 5 6 9 Some outlets are not working 30 16 5 6 9 C1: Category 1 – Dormitory, C2: Category 2 – Classrooms and seminars, C3: Category 3 – Libraries, C4: Category 4 – Laboratories, C5: Category 5 – others (mixed purpose buildings) More than half of the building blocks had visible foundation defects like set tlements and cracks. The main causes of the settlement are poor compaction, weak bearing soil, moisture changes, and soil co nsolidation. All studied buildings had cracks in common areas such as exterior walls, interior walls at door and window corners, floors, and ceilings. General measures to protect cracks include correct specifications for mortar, concrete, and all other materials and works, good construction practices (workmanship), and avoiding construction during severe weather cond itions. Fig. 2 Cracks on structural beam and slab: classroom and dormitory, Woliso Campus 2) Based on the visual inspection made, the following crack types were identified, an d their possible repair methods were suggested. Thermal movement : It is one of the most common cracks in buildings, and it is caused by temperature variations, thermal expansion coefficients, and other physical properties of the components. It has been observed on both internal and external walls subjected to significant thermal variation and prone to cracking. Shrinkage: Most building materials expand when wet and shrink when dry. Two m ain factors cause shrinkage in cement concrete and cement mortar. Excessive water in the mortar mix can cause shrinka ge. The second is cement quantity: The more affluent the mix, the greater the shrinkage. Chemical Reaction : It can occur due to the concrete's composition or materials that come into contact wit h it after it hardens. Concrete may crack over time due to expansive reactions between active silica ag gregate and alkalis from cement hydration, admixtures, or external sources. Elastic Deformation: Elastic Deformation occurs when a material strains under stress. When two m aterials of different elastic properties are built together under the effect of load, different shear stress es create cracks at the junction. Both dead and live loads are the major cause of elastic deformation in any structural component of a bu ilding. Suggested repair methods: Injection of Epoxy : The method is very useful for repairing dormant or nonmoving cracks in slabs, walls, columns, and piers. Sealing and routing : The method is preferably used in conditions that require repair and mai ntenance and where repair of structures is unnecessary. In the process, the crack is enlarged along its face, which is exposed, which is followed by filling with a suitable sealant. https://doi.org/10.37896/jxu15.8/013 151Journal of Xidian University VOLUME 15, ISSUE 8, 2021ISSN No:1001-2400 http://xadzkjdx.cn/ Dry packing : It is the process of placing low moisture content mortar, followed by tamping the placed mortar into a particular area. Water may leak from a building's roof or floor if not built properly. Small amounts of water can cause significant issues in a building. On average, 82 percent of the structures studied had moistu re leakage. Water leakage causes paint peeling, cracks, and staining, which reduces building life and performance. Fig. 3 Moisture leakage problems: dormitory blocks, main Campus Almost every building in the study had plastering and painting issues. The most common and frequently identified plastering defects were crazing, flaking, and peeling Using sand containing exce ssive amounts of dust (15% by mass), inadequate substrate preparation, insufficient cement, excessively thick layers, adding extra water to o long after first mixing (re-tempering), evaporation (when plastering in sun and wind), and inadequate substrate preparation is all causes of sand failure. Fig. 4 Paint defects observed on walls from the four campuses. 3) On-progress buildings status assessment on the basis of their materials quality control im plementation and workmanship All G+2 and higher buildings under construction on all Ambo Univers ity campuses were chosen for the study. The materials quality control and workmanship of these buildings are discussed using data from contractors, consultants, clients, site observations, and desk studies. 3.1 Assessment on AU Referral and Teaching Hospital (Building A) The AU Referral and Teaching Hospital are one of the university's largest cons truction projects. Site inspections, contractor and consultant interviews, and contract document reviews were co nducted to assess the stakeholders' materials quality control implementation and project work compliance with pre-set specif ications and standards. Since the project is ongoing, foundations, concrete, brick, hollow concrete block, and reinforcement work has been seen. TABLE XXV ON-PROGRESS BUILDING PROFILE No. Project Name Given name Height No. of Bldgs. Status Location 1 AU Referral and Teaching Hospital A 2B+G+5 1 On-progress Main Campus 2 Classroom, lab, Office (3 wings) B G+5 1 On-progress Main Campus 3 President Office C G+6 1 On-progress Main Campus https://doi.org/10.37896/jxu15.8/013 152Journal of Xidian University VOLUME 15, ISSUE 8, 2021ISSN No:1001-2400 http://xadzkjdx.cn/ 4 Main Administration, Awaro (5 Wings) D G+3 1 On-progress Awaro Campus 5 Classroom and Clinic E G+4 2 On-progress Guder Campus 6 Classroom, lab, Office (3 wings) F G+5 1 On-progress Woliso Campus According to the general technical specification document, materials and workmanship must meet technical specifications and be subject to periodic testing by the engineer (MH-Engineering, 2010 ). Materials must be approved or tested first. The engineer may reject damaged or deteriorated materials and remove them immediately. Desp ite this, the Contractor was seen using damaged materials like bricks as membranes on retaining walls. The stone masonry also didn't meet the technical requirements. Fig. 5 Settlement and non-conforming backfill materials The concrete strength is good, as indicated in the test results. However, th e workmanship had some issues, particularly between columns and beams. These connection issues may eventually reduce building performance and increase maintenance costs. The materials delivered to the site generally match the specifications and contracts, but there was a problem with materials handling. Those built structures also had poor workmanship. 3.2 Assessment on Classroom, lab, Office (3 wings) (Building B and F) Both Ambo University-Main Campus and Wolliso Campus buildings ar e still in the foundation stage. The materials quality management and workmanship of these twin buildings are discussed. The researcher has tried to obtain test results such as concrete, soil, and other submittals. However, other materials and works like reinforcement bars, backfill materials, and backfill compaction density could not be tested or inspected. Building F's foundation work was flooded due to the rainy season. The excavated area was flooded, but the Contractor was laying footings, and the r ainwater will affect the building. 3.3. Assessment of President Office (Building C) The president's office building was left with few finishing touches an d ready to go during the study. The building's visible parts were inspected visually, and documents were collected and studied for its history. The material testing and inspection results were compared to the main contract document and found to be acceptable. Th e engineer's approvals and material and fixture submittals show the materials and fixtures used for the project. As seen on the site, the building had a few defects due to poor workmanship. 3.4 Assessment on Main Administration, Awaro (5 Wings) (Building D) While the research is being conducted, Building D, the Awaro campus's main administration building, has various functions. Interviews, site visits, and a desk study were used to analyze the projec t's construction history. More than 50% of material tests and inspection documents were not obtained, making it difficult to determi ne if all requirements were met. A visual inspection revealed some issues with the project's workmanship: poor external wall tili ng, windowsills, flooring, screenings, and other finishing work. Extra beams with no loads and no functions w ere seen around the roof. 3.5 Assessment on Classroom and Clinic (Building E) The building is located in Ambo University, Guder Campus, and it was u nder construction while the study is conducted. Materials management like sand, gravel, marble, floor tiles and others have b een observed. The Contractor was using Senkele sands without sieving and washing. As it is surveyed in the literatur e, Senkele sand has 14.28% silt content, which exceeded 6% based on Ethiopian Standard Specification. Coarse aggregates were used by mixing from two different-sized aggregates. Both https://doi.org/10.37896/jxu15.8/013 153Journal of Xidian University VOLUME 15, ISSUE 8, 2021ISSN No:1001-2400 http://xadzkjdx.cn/ Contractor and consultant were not seen for a long time on the site, resu lting in very poor workmanship on the project. It has been observed while the workers were placed concrete beyond the thickness and chisel ing after setting. Fig. 6 Class Room building, Guder Campus 4) Possible mitigations for the observed problems and basic recommendations f or the present and future building projects Ambo University has no defect-free building, even if the degr ee and type of defects vary from block to block. Several defects were noted and discussed in the previous section due to non-complia nce materials and poor workmanship. The following are possible mitigation measures to prevent further damage to the buildings. 4.1 For Existing Buildings To address the current issues with the university's building quality, q ualified construction industry professionals should be appointed. All necessary non-destructive tests and visual inspections s hould be performed, and remedial actions should be taken based on the results. The use of hydraulic water-stop cement to rep air cracks and leaks in concrete and walls requires a proper preparation. To successfully repair a crack, it must be prepared b y widening it to three-quarters of an inch and removing loose debris. It can permanently stop active water leaks. Remove any s uspect plasterwork. Prior to applying a suitable grade of plaster, prepare the background and apply a coat of Thistle Bond-It. F bu ilding defects should be identified and repaired promptly to avoid significant damage and costs to a building's foundation and other s tructural components. It is mandatory to perform all required maintenance professionally. D) For Under-Construction Buildings Contractors and consultants should devote their entire time to overseein g the construction of buildings. Consultants should monitor the project daily and check the work against the specif ications and contract documents. All building materials and fixtures should be tested and inspected according to the manufacturer's specifications. Generally, damaged materials should b e removed from the site. Only two contractors use Ambo sandstone th at has been washed from the Senkele and Aleltu sites [ 11]. All contractors using the specified sand should sieve and wash it first. Assign at least one technician familiar with the requirements who can guide the tradesmen in material selection and work execution to achie ve the required workmanship quality. IV. CONCLUSION The study's findings lead to the following conclusions: To meet all require ments and improve the quality of building projects, it must first identify and recognize the primary factors affecti ng the materials and workmanship. There are 15 primary factors affecting building construction materials quality and workmansh ip, each with sub-factors. All of these factors are ranked in terms of their importance in the project's overall success. Observ ations, desk studies, and interviews were used to assess the condition of Ambo University buildings based on their construction materials an d workmanship. The findings indicated that there was no defect-free building in Ambo University, and degree and type of defects will vary. Hence, the contractors and consultants play a vital role in the success of building projects because they manag e materials and labor. It is beneficial to test and inspect all materials in accordance with the standard specifications. Removing non-co mpliant materials from the site and only using new materials as specified in the contract documents will improve building perfo rmance and quality. ACKNOWLEDGMENT The authors express their profound gratitude to Ambo University Hachal u Hundessa, Institute of Technology, Ambo University, for all supports extended during the conduct of the research activities. https://doi.org/10.37896/jxu15.8/013 154Journal of Xidian University VOLUME 15, ISSUE 8, 2021ISSN No:1001-2400 http://xadzkjdx.cn/