Specification is the specific description of project which describe the nature and class of work, material to be used.

Importance of specification:

• Serves as guide for site engineers.
• Helps to clear misunderstanding and mistake of project.
• For accurate cost estimation and budgeting.
• Help to verify and check strength of material.
• Helps to meet final outcomes of project.

Purpose of specification:

• To specify nature of work.
• To estimate quantity and cost.
• To identify quantity of material.
• To identify material proportion.
• To identify type of workmanship.

Writing specification:

1. Description of material

• Provide clear description of material.
• Includes brand name and model name.

2. Workmanship

• Describe level of workmanship.

3. Tools

• Describe tools and equipment used.
• Provide rental and purchase requirement.

4. Work protection

• Instruction to protect project.

5. Expression

• Use clear and concise language.

6. Clauses of specification

• Include condition to meet work.
• Describe warranties or guarantees of work.

1.2 Specification of RCC

1. Specification material:

a. Cement:

• OPC cement is used i.e. 43 grade & IS 269:2015.

b. Coarse aggregate:

• Should hard dense and durable material like granite, basalt or limestone.
• Maximum size should exceed ¼ ^th of minimum thickness of member.

c. Fine aggregate:

• Should be clean free from dust, clay and organic material.
• Fineness modulus should not be more than 3.1 and less than 2.3.

d. Water:

• Clean water free from harmful impurities like oil, acid etc.

2. Combination of material:

• Should be M20 grade concrete.
• Mix proportion of cement, fine aggregate, coarse aggregate and water should be 1:1.5:3: 0.5 by weight.
• Concrete should mix mechanically using batch mixture.

3. Steel Reinforcement using IS code:

a. According IS 1786:2008, steel bar should have minimum yield strength of 415 N/mm².

b. Steel bar should be free from rust, oil and any deleterious material.

c. As per IS 456:2000, cover should be measured from outer surface of reinforcement to surface of concrete.

d. Reinforcement should be placed as per drawing.

1.3 Specification of brick masonry

1. Specification of material:

a. Brick:

• Use 1^st class brick.
• Should be in uniform shape and size.

b. Mortar:

• Should be good quality and free from lumps.
• Ratio should be (C:S:W = 1:4:0.5).

2. Combination of material:

a. Brick masonry:

• Should be laid in English bond.

b. Reinforced brick masonry:

• Should be laid in Flemish bond.

3. Steel reinforced using IS code:

• As per IS 432:1982
  • Minimum diameter of steel bar = 6 mm
  • Minimum cover of steel reinforcement = 15 mm
• Placed in alternative course.
• Spacing should not be more than 300 mm in horizontal and 450 mm in vertical direction.

1.4 Specification of PCC

1. Material specification:

a. Cement:

• As per IS 8112, use OPC of grade 43.

b. Coarse aggregate:

• As per IS 383, nominal size 20 mm.

c. Fine aggregate:

• Should be free from dust and organic matter.

2. Combination of material:

• W/C ratio = 0.5
• (Cement: Sand: Aggregate) =  (1:1.5: 3)

3. Steel reinforcement:

• As per IS 1786
  • Grade of steel should be Fe500 or Fe415
  • Diameter not more than 16 mm.
• Spacing not more than 150 mm and not less than 75 mm.
• Should be free from rust and impurities.

References:

• Dutta, B.N. – Estimating and Costing in Civil Engineering, UBS Publishers, New Delhi.
• CPWD (Central Public Works Department), India – Standard Schedule of Rates and Analysis of Rates.
• IS 1200 – Indian Standard for Method of Measurement of Building and Civil Engineering Works, Bureau of Indian Standards (BIS).
• Punmia, B.C. – Estimating and Costing, Laxmi Publications.
• Building Estimation and Costing Notes – Department of Civil Engineering, Pokhara University.
• MoUD Nepal – Standard Norms and Guidelines for Public Infrastructure Development Projects.

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