Specification

Specification. A written statement describing in detail the quality of the materials to be used, the workmanship expected, the method of doing the work and the method of its measurement and payment. The drawing shows the size and shape of the work; the specification states its quality. Only together do the two define the work completely.

Purpose / role of specifications

1. To describe the quality and class of materials and the workmanship required, which a drawing cannot show.
2. To form part of the contract document, and so be legally binding on both parties.
3. To provide the basis for the analysis of rates — a rate cannot be worked out until the item is defined.
4. To guide the contractor in executing the work and the engineer in supervising and accepting it.
5. To put every tenderer on the same footing, so that quoted rates are comparable.
6. To fix the method of measurement and payment of each item.
7. To prevent disputes, by removing ambiguity about what was intended.
8. To lay down the tests to be carried out and the standards to be met.
9. To specify the equipment, tools and plant to be engaged on the work, so that they can be arranged beforehand.
10. To fix the responsibility of the contractor for quality and for defects.

Techniques / principles of writing a specification

1. Be clear and unambiguous. Use simple, direct language; one sentence should carry one requirement. Avoid words such as "good", "suitable", "proper", "best quality" — they are unenforceable.
2. Be complete. Cover material, proportion, workmanship, method, tolerance, testing, curing, protection, and the mode of measurement and payment.
3. Be brief. Say a thing once. Repetition creates contradiction.
4. Use the imperative or the word "shall" — "bricks shall be first class". "Should" and "may" are advisory and unenforceable.
5. Follow the sequence of construction — materials first, then workmanship, then measurement and payment.
6. Refer to standards (IS / NS codes) rather than reproducing them, but quote the number and the year.
7. Do not contradict the drawing or the conditions of contract; if there is a conflict, state which prevails.
8. Quantify wherever possible — give numbers, tolerances and limits, not adjectives. "Joints not exceeding 10 mm", not "thin joints".
9. Do not specify the impossible or the unavailable; the specification must be practicable at that site.
10. Do not encroach on the contractor's means unless the method genuinely matters — over-specifying transfers the risk back to the owner.
11. Write in a standard order and number the clauses, so that they can be referred to.
12. Check it against the bill of quantities, so that every item priced is specified and every item specified is priced.

ENCE 351 §8.1 and §8.4.

a) Role of specifications in a construction project

Specification. A written statement describing in detail the quality of the materials to be used, the workmanship expected, the method of doing the work and the method of its measurement and payment. The drawing shows the size and shape of the work; the specification states its quality. Only together do the two define the work completely.

Purpose / role of specifications

1. To describe the quality and class of materials and the workmanship required, which a drawing cannot show.
2. To form part of the contract document, and so be legally binding on both parties.
3. To provide the basis for the analysis of rates — a rate cannot be worked out until the item is defined.
4. To guide the contractor in executing the work and the engineer in supervising and accepting it.
5. To put every tenderer on the same footing, so that quoted rates are comparable.
6. To fix the method of measurement and payment of each item.
7. To prevent disputes, by removing ambiguity about what was intended.
8. To lay down the tests to be carried out and the standards to be met.
9. To specify the equipment, tools and plant to be engaged on the work, so that they can be arranged beforehand.
10. To fix the responsibility of the contractor for quality and for defects.

b) Principles of writing a technical specification

Techniques / principles of writing a specification

1. Be clear and unambiguous. Use simple, direct language; one sentence should carry one requirement. Avoid words such as "good", "suitable", "proper", "best quality" — they are unenforceable.
2. Be complete. Cover material, proportion, workmanship, method, tolerance, testing, curing, protection, and the mode of measurement and payment.
3. Be brief. Say a thing once. Repetition creates contradiction.
4. Use the imperative or the word "shall" — "bricks shall be first class". "Should" and "may" are advisory and unenforceable.
5. Follow the sequence of construction — materials first, then workmanship, then measurement and payment.
6. Refer to standards (IS / NS codes) rather than reproducing them, but quote the number and the year.
7. Do not contradict the drawing or the conditions of contract; if there is a conflict, state which prevails.
8. Quantify wherever possible — give numbers, tolerances and limits, not adjectives. "Joints not exceeding 10 mm", not "thin joints".
9. Do not specify the impossible or the unavailable; the specification must be practicable at that site.
10. Do not encroach on the contractor's means unless the method genuinely matters — over-specifying transfers the risk back to the owner.
11. Write in a standard order and number the clauses, so that they can be referred to.
12. Check it against the bill of quantities, so that every item priced is specified and every item specified is priced.

ENCE 351 §8.1 and §8.4.

Specification. A written statement describing in detail the quality of the materials to be used, the workmanship expected, the method of doing the work and the method of its measurement and payment. The drawing shows the size and shape of the work; the specification states its quality. Only together do the two define the work completely.

Types of specification

Specifications are classified in two ways.

A. By the amount of detail

B. By the way the requirement is expressed

• Prescriptive (method) specification — states exactly what materials to use and how to do the work. The designer takes responsibility for the result.
• Performance specification — states the result to be achieved (for example, concrete of 20 N/mm² at 28 days) and leaves the means to the contractor, who then carries the responsibility.
• Proprietary specification — names a particular brand or manufacturer.
• Reference specification — refers to a published standard (IS, NS, ASTM, DoR / DUDBC standard specification) instead of repeating its text.
• Open and closed specifications — an open one allows equivalents, a closed one does not.

Techniques / principles of writing a specification

1. Be clear and unambiguous. Use simple, direct language; one sentence should carry one requirement. Avoid words such as "good", "suitable", "proper", "best quality" — they are unenforceable.
2. Be complete. Cover material, proportion, workmanship, method, tolerance, testing, curing, protection, and the mode of measurement and payment.
3. Be brief. Say a thing once. Repetition creates contradiction.
4. Use the imperative or the word "shall" — "bricks shall be first class". "Should" and "may" are advisory and unenforceable.
5. Follow the sequence of construction — materials first, then workmanship, then measurement and payment.
6. Refer to standards (IS / NS codes) rather than reproducing them, but quote the number and the year.
7. Do not contradict the drawing or the conditions of contract; if there is a conflict, state which prevails.
8. Quantify wherever possible — give numbers, tolerances and limits, not adjectives. "Joints not exceeding 10 mm", not "thin joints".
9. Do not specify the impossible or the unavailable; the specification must be practicable at that site.
10. Do not encroach on the contractor's means unless the method genuinely matters — over-specifying transfers the risk back to the owner.
11. Write in a standard order and number the clauses, so that they can be referred to.
12. Check it against the bill of quantities, so that every item priced is specified and every item specified is priced.

ENCE 351 §8.2 and §8.4.

Specification. A written statement describing in detail the quality of the materials to be used, the workmanship expected, the method of doing the work and the method of its measurement and payment. The drawing shows the size and shape of the work; the specification states its quality. Only together do the two define the work completely.

Types of specification

Specifications are classified in two ways.

A. By the amount of detail

B. By the way the requirement is expressed

• Prescriptive (method) specification — states exactly what materials to use and how to do the work. The designer takes responsibility for the result.
• Performance specification — states the result to be achieved (for example, concrete of 20 N/mm² at 28 days) and leaves the means to the contractor, who then carries the responsibility.
• Proprietary specification — names a particular brand or manufacturer.
• Reference specification — refers to a published standard (IS, NS, ASTM, DoR / DUDBC standard specification) instead of repeating its text.
• Open and closed specifications — an open one allows equivalents, a closed one does not.

Techniques / principles of writing a specification

1. Be clear and unambiguous. Use simple, direct language; one sentence should carry one requirement. Avoid words such as "good", "suitable", "proper", "best quality" — they are unenforceable.
2. Be complete. Cover material, proportion, workmanship, method, tolerance, testing, curing, protection, and the mode of measurement and payment.
3. Be brief. Say a thing once. Repetition creates contradiction.
4. Use the imperative or the word "shall" — "bricks shall be first class". "Should" and "may" are advisory and unenforceable.
5. Follow the sequence of construction — materials first, then workmanship, then measurement and payment.
6. Refer to standards (IS / NS codes) rather than reproducing them, but quote the number and the year.
7. Do not contradict the drawing or the conditions of contract; if there is a conflict, state which prevails.
8. Quantify wherever possible — give numbers, tolerances and limits, not adjectives. "Joints not exceeding 10 mm", not "thin joints".
9. Do not specify the impossible or the unavailable; the specification must be practicable at that site.
10. Do not encroach on the contractor's means unless the method genuinely matters — over-specifying transfers the risk back to the owner.
11. Write in a standard order and number the clauses, so that they can be referred to.
12. Check it against the bill of quantities, so that every item priced is specified and every item specified is priced.

ENCE 351 §8.2 and §8.4.

a) General and detailed specification defined and distinguished

General specification gives a brief, overall description of the class and nature of the work as a whole, without going into individual items. It conveys the general idea of the building and is used in the report and for approximate estimates.

Detailed specification describes each item of work separately and in full — the materials, their proportions, the workmanship, the method of execution, the curing, the tests and the mode of measurement and payment. It forms part of the contract document and governs execution and payment.

Types of specification

Specifications are classified in two ways.

A. By the amount of detail

B. By the way the requirement is expressed

• Prescriptive (method) specification — states exactly what materials to use and how to do the work. The designer takes responsibility for the result.
• Performance specification — states the result to be achieved (for example, concrete of 20 N/mm² at 28 days) and leaves the means to the contractor, who then carries the responsibility.
• Proprietary specification — names a particular brand or manufacturer.
• Reference specification — refers to a published standard (IS, NS, ASTM, DoR / DUDBC standard specification) instead of repeating its text.
• Open and closed specifications — an open one allows equivalents, a closed one does not.

b) Detailed specification of 1:4 cement plaster on brick wall

Detailed specification — 12 mm cement plaster 1:4 on brick wall

1. Scope. Twelve millimetre thick cement plaster in cement sand mortar 1:4 on internal or external brick wall surfaces.

2. Materials. Cement shall be ordinary Portland cement conforming to the relevant IS / NS standard, fresh and free from lumps. Sand shall be clean, sharp, well-graded river sand passing a 2.36 mm sieve, free from clay, silt, salt and organic matter, with silt content not exceeding 4%; it shall be screened and washed if necessary. Water shall be clean and fit for drinking.

3. Mortar. Cement and sand shall be measured by standard boxes in the proportion 1:4, mixed dry on a clean watertight platform until uniform in colour, then mixed with the minimum water needed for workability. Only as much mortar as can be used within 30 minutes shall be prepared; re-tempering is not permitted.

4. Preparation of the surface

• All joints of the brickwork shall be raked out to a depth of 12–15 mm while the mortar is green, to provide a key.
• The surface shall be brushed clean of dust, loose mortar, efflorescence, oil and grease, and any projecting burr removed.
• The surface shall be thoroughly wetted and kept damp for at least 6 hours before plastering, but shall not be soaking wet at the moment of application.
• Any unevenness exceeding 12 mm shall be made good in advance with mortar; plaster shall not be used to correct bad brickwork.

5. Application

• Screeds shall be applied first to fix the thickness and the plane — either gauge patches about 15 × 15 cm at not more than 2 m apart, or narrow strips of plaster about 10 cm wide at about 1 m centres, the gaps between the strips being filled immediately with mortar.
• Mortar shall be applied with a trowel in a single coat 12 mm thick, forced well into the joints, and brought to a true surface by working a wooden straight edge over the screeds with a small upward and sideways motion.
• The surface shall then be finished with a wooden float to a true, even and smooth surface, free from cracks and undulations. A steel trowel finish shall be used only where specified.
• Plastering shall be started from the top and worked downwards.
• Work shall be closed at the end of a wall or at a natural break, never in the middle of a panel, and the day's joint shall not be visible.
• All corners, arrises and junctions shall be true, sharp and rounded as directed; internal corners shall not be rounded unless specified.

6. Curing. Curing shall start 12 to 24 hours after the plaster is laid, once it has hardened enough not to be damaged, and shall continue by keeping the surface constantly moist for at least 7 days. The plaster shall be protected from rain, direct sun and frost during this period.

7. Defects. Plaster that sounds hollow when tapped, or shows cracks, blisters or efflorescence, shall be cut out in complete rectangular patches and redone at the contractor's cost.

8. Measurement and payment. Plastering shall be measured in square metres (m²) of the finished surface, separately for each thickness and each mix, and separately for internal and external work. Deductions for openings shall follow IS 1200:

No deduction shall be made for the ends of beams, posts or rafters. Payment shall be per m², the rate including materials, labour, scaffolding, curing and protection.

ENCE 351 §8.2 and §8.5.

Types of specification

Specifications are classified in two ways.

A. By the amount of detail

B. By the way the requirement is expressed

• Prescriptive (method) specification — states exactly what materials to use and how to do the work. The designer takes responsibility for the result.
• Performance specification — states the result to be achieved (for example, concrete of 20 N/mm² at 28 days) and leaves the means to the contractor, who then carries the responsibility.
• Proprietary specification — names a particular brand or manufacturer.
• Reference specification — refers to a published standard (IS, NS, ASTM, DoR / DUDBC standard specification) instead of repeating its text.
• Open and closed specifications — an open one allows equivalents, a closed one does not.

Importance of specification in construction

1. It completes the drawing. A drawing gives dimensions only. Two buildings of identical drawings can differ enormously in cost and quality; the specification is what distinguishes them.
2. It is the legal backbone of the contract. In any dispute, the specification is the document to which both parties and the arbitrator turn.
3. It governs the rate. The analysis of rates begins from the specification; change the mix from 1:2:4 to 1:1½:3 and the rate changes at once.
4. It ensures fair competition. All tenderers price the same quality, so the lowest bid is genuinely the lowest.
5. It is the standard of acceptance. The engineer accepts or rejects work by comparing it with the specification.
6. It protects the owner against the use of inferior materials and poor workmanship.
7. It protects the contractor too, by defining exactly what he is obliged to do — and no more.
8. It fixes measurement and payment, and so avoids disputes over billing.
9. It records the intention for future maintenance, repair and valuation.
10. A tender paper without a specification is baseless — the contractor has nothing on which to build his rate, and the owner nothing against which to judge it.

ENCE 351 §8.2 and §8.3.

a) General and detailed specification distinguished

Types of specification

Specifications are classified in two ways.

A. By the amount of detail

B. By the way the requirement is expressed

• Prescriptive (method) specification — states exactly what materials to use and how to do the work. The designer takes responsibility for the result.
• Performance specification — states the result to be achieved (for example, concrete of 20 N/mm² at 28 days) and leaves the means to the contractor, who then carries the responsibility.
• Proprietary specification — names a particular brand or manufacturer.
• Reference specification — refers to a published standard (IS, NS, ASTM, DoR / DUDBC standard specification) instead of repeating its text.
• Open and closed specifications — an open one allows equivalents, a closed one does not.

b) Detailed specification for brick work in 1:4 cement sand mortar

Detailed specification — first class brickwork in cement sand mortar

1. Scope. This specification covers first class brickwork in walls, piers and similar work, laid in cement sand mortar of the proportion stated in the item.

2. Materials

• Bricks shall be first class, table moulded, thoroughly burnt in a kiln, of uniform deep red, cherry or copper colour, free from cracks, chips, flaws and lumps of lime or organic matter. They shall have sharp, straight and square edges, plane faces and uniform size, and shall give a clear metallic ringing sound when struck against one another. The minimum crushing strength shall be 105 kg/cm² (10.5 N/mm²), and a dry brick shall not absorb more than one-sixth of its weight after one hour's immersion (about 20% of the dry weight after 24 hours). Bricks shall not break when dropped flat on hard ground from about 1 m.
• Cement shall be ordinary Portland cement conforming to the relevant IS / NS standard, fresh, free from lumps, and stored clear of the ground and damp.
• Sand shall be clean, sharp, coarse river sand, free from clay, silt, salt and organic matter; silt content not more than 4%. It shall be screened and washed if necessary.
• Water shall be clean and fit for drinking, free from oil, acid, alkali and organic matter.

3. Mortar. Cement and sand shall be measured by boxes of standard size in the proportion stated in the item, mixed dry on a clean watertight platform until the mixture is of uniform colour, and then mixed with the minimum water necessary to give a workable consistency. Only so much mortar shall be prepared as can be used within 30 minutes of adding water. Mortar left unused beyond its initial setting time shall be rejected; re-tempering is not permitted.

4. Soaking. Bricks shall be fully soaked in clean water for at least two hours — and for first class work four hours — before use, stacked on clean wooden planks clear of mud, and allowed to become surface-dry before laying, so that they neither absorb water from the mortar nor float on it.

5. Workmanship

• Brickwork shall be laid in English bond unless otherwise specified, this being the strongest bond, with alternate courses of headers and stretchers and a queen closer next to the quoin header.
• Bricks shall be laid with their frogs upward, on a full bed of mortar, and well pressed so that the mortar is squeezed out and the joint is completely filled.
• Joints shall be full and shall not exceed 6 mm in cement mortar or 10 mm in lime mortar. Vertical joints must break — that is, they shall not come one above the other in consecutive courses.
• No bats shall be used except where they are absolutely required to obtain the specified bond or the dimensions of a course.
• Each course shall be truly horizontal and the face truly vertical, checked with a spirit level and plumb bob. The work shall be taken up in level courses all round.
• The height raised in one day shall not exceed 1.0 m, to avoid unequal settlement of the fresh work.
• Where the work has to be left, it shall be stepped or raked back at an angle not steeper than 45°; toothing shall not be allowed.
• The face of the wall shall be kept clean of mortar droppings. Where the surface is to be plastered, the joints shall be raked out to a depth of 12–15 mm while the mortar is green, to give a key to the plaster; where it is to be pointed, the joints shall be raked as required for pointing.
• Openings, chases, holdfasts and embedded fixtures shall be provided as the work proceeds; cutting afterwards is not permitted.

6. Curing. The work shall be kept constantly moist on all faces for at least 10 to 14 days, by sprinkling water at least twice a day and by covering with wet gunny bags. At the end of each day's work a trough at least 2.5 cm deep shall be formed on the top of the wall with weak mortar or mud edging and kept flooded with water. Freshly laid work shall be protected from rain, sun and frost; during rain no brickwork shall be carried out unless it can be protected for 24 hours.

7. Scaffolding. Single scaffolding may be used for ordinary work; double scaffolding shall be used for important work and where the wall face is to be exposed, so that no hole is left in the finished face.

8. Measurement and payment. Brickwork shall be measured in cubic metres (m³), the dimensions being taken to the nearest 0.01 m. No deduction is made for the bearings of lintels and beams up to 0.1 m³ in volume, nor for openings up to 0.1 m² in area. Brickwork of each thickness, each class of brick and each mortar mix shall be measured separately, and separately in foundation, in plinth and in superstructure. Payment shall be made per m³ at the rate quoted, which shall include all materials, labour, scaffolding, curing and protection.

The mix here is 1:4, which is richer than the 1:6 normally used for ordinary walls; it is specified for load-bearing walls, for work below plinth level and in wet situations. For 1 m³ of wet 1:4 mortar the quantities are cement 1.30 × (1/5) = 0.26 m³ = 374.4 kg = 7.49 bags, and sand 1.30 × (4/5) = 1.04 m³.

ENCE 351 §8.2 and §8.5.

a) Why specification is important in construction contracts

Importance of specification in construction

1. It completes the drawing. A drawing gives dimensions only. Two buildings of identical drawings can differ enormously in cost and quality; the specification is what distinguishes them.
2. It is the legal backbone of the contract. In any dispute, the specification is the document to which both parties and the arbitrator turn.
3. It governs the rate. The analysis of rates begins from the specification; change the mix from 1:2:4 to 1:1½:3 and the rate changes at once.
4. It ensures fair competition. All tenderers price the same quality, so the lowest bid is genuinely the lowest.
5. It is the standard of acceptance. The engineer accepts or rejects work by comparing it with the specification.
6. It protects the owner against the use of inferior materials and poor workmanship.
7. It protects the contractor too, by defining exactly what he is obliged to do — and no more.
8. It fixes measurement and payment, and so avoids disputes over billing.
9. It records the intention for future maintenance, repair and valuation.
10. A tender paper without a specification is baseless — the contractor has nothing on which to build his rate, and the owner nothing against which to judge it.

b) Major techniques followed in writing a specification

Techniques / principles of writing a specification

1. Be clear and unambiguous. Use simple, direct language; one sentence should carry one requirement. Avoid words such as "good", "suitable", "proper", "best quality" — they are unenforceable.
2. Be complete. Cover material, proportion, workmanship, method, tolerance, testing, curing, protection, and the mode of measurement and payment.
3. Be brief. Say a thing once. Repetition creates contradiction.
4. Use the imperative or the word "shall" — "bricks shall be first class". "Should" and "may" are advisory and unenforceable.
5. Follow the sequence of construction — materials first, then workmanship, then measurement and payment.
6. Refer to standards (IS / NS codes) rather than reproducing them, but quote the number and the year.
7. Do not contradict the drawing or the conditions of contract; if there is a conflict, state which prevails.
8. Quantify wherever possible — give numbers, tolerances and limits, not adjectives. "Joints not exceeding 10 mm", not "thin joints".
9. Do not specify the impossible or the unavailable; the specification must be practicable at that site.
10. Do not encroach on the contractor's means unless the method genuinely matters — over-specifying transfers the risk back to the owner.
11. Write in a standard order and number the clauses, so that they can be referred to.
12. Check it against the bill of quantities, so that every item priced is specified and every item specified is priced.

ENCE 351 §8.3 and §8.4.

a) Types of specification

Types of specification

Specifications are classified in two ways.

A. By the amount of detail

B. By the way the requirement is expressed

• Prescriptive (method) specification — states exactly what materials to use and how to do the work. The designer takes responsibility for the result.
• Performance specification — states the result to be achieved (for example, concrete of 20 N/mm² at 28 days) and leaves the means to the contractor, who then carries the responsibility.
• Proprietary specification — names a particular brand or manufacturer.
• Reference specification — refers to a published standard (IS, NS, ASTM, DoR / DUDBC standard specification) instead of repeating its text.
• Open and closed specifications — an open one allows equivalents, a closed one does not.

b) Importance of specification

Importance of specification in construction

1. It completes the drawing. A drawing gives dimensions only. Two buildings of identical drawings can differ enormously in cost and quality; the specification is what distinguishes them.
2. It is the legal backbone of the contract. In any dispute, the specification is the document to which both parties and the arbitrator turn.
3. It governs the rate. The analysis of rates begins from the specification; change the mix from 1:2:4 to 1:1½:3 and the rate changes at once.
4. It ensures fair competition. All tenderers price the same quality, so the lowest bid is genuinely the lowest.
5. It is the standard of acceptance. The engineer accepts or rejects work by comparing it with the specification.
6. It protects the owner against the use of inferior materials and poor workmanship.
7. It protects the contractor too, by defining exactly what he is obliged to do — and no more.
8. It fixes measurement and payment, and so avoids disputes over billing.
9. It records the intention for future maintenance, repair and valuation.
10. A tender paper without a specification is baseless — the contractor has nothing on which to build his rate, and the owner nothing against which to judge it.

c) Elements used in writing a detailed specification

A detailed specification for any item is written in a fixed order, and these are its elements:

1. Scope / title of the item — what work the clause covers.
2. Materials — the class, quality, source and the test each material must pass.
3. Proportion / mix — the ratio, how it is measured, and the water cement ratio where applicable.
4. Preparation — setting out, preparing the surface or the base, soaking.
5. Workmanship and method of execution — how the work is actually to be done, in what sequence, in what lifts, with what equipment.
6. Tolerances and finish — permissible deviation in line, level and thickness, and the surface finish required.
7. Curing and protection — period and method.
8. Tests — the tests to be carried out, their frequency and the acceptance criteria.
9. Defects and rectification — what constitutes defective work and how it is to be made good.
10. Mode of measurement and payment — the unit, the deduction rules, and what the rate is deemed to include.

ENCE 351 §8.2, §8.3 and §8.5.

a) Importance of specification

Importance of specification in construction

1. It completes the drawing. A drawing gives dimensions only. Two buildings of identical drawings can differ enormously in cost and quality; the specification is what distinguishes them.
2. It is the legal backbone of the contract. In any dispute, the specification is the document to which both parties and the arbitrator turn.
3. It governs the rate. The analysis of rates begins from the specification; change the mix from 1:2:4 to 1:1½:3 and the rate changes at once.
4. It ensures fair competition. All tenderers price the same quality, so the lowest bid is genuinely the lowest.
5. It is the standard of acceptance. The engineer accepts or rejects work by comparing it with the specification.
6. It protects the owner against the use of inferior materials and poor workmanship.
7. It protects the contractor too, by defining exactly what he is obliged to do — and no more.
8. It fixes measurement and payment, and so avoids disputes over billing.
9. It records the intention for future maintenance, repair and valuation.
10. A tender paper without a specification is baseless — the contractor has nothing on which to build his rate, and the owner nothing against which to judge it.

b) Importance of valuation

Valuation determines the fair present worth of a property. It is required for buying and selling, for fixing rent, for a mortgage or bank loan, for property and wealth taxation, for compulsory acquisition and the compensation payable, for insurance, for partition and probate, for court cases and arbitration, for fixing an upset price at auction, and for investment decisions.

c) Methods of working out the valuation of a property

ENCE 351 §7.4 and §8.3.

a) Why specification is important in construction contracts

Importance of specification in construction

1. It completes the drawing. A drawing gives dimensions only. Two buildings of identical drawings can differ enormously in cost and quality; the specification is what distinguishes them.
2. It is the legal backbone of the contract. In any dispute, the specification is the document to which both parties and the arbitrator turn.
3. It governs the rate. The analysis of rates begins from the specification; change the mix from 1:2:4 to 1:1½:3 and the rate changes at once.
4. It ensures fair competition. All tenderers price the same quality, so the lowest bid is genuinely the lowest.
5. It is the standard of acceptance. The engineer accepts or rejects work by comparing it with the specification.
6. It protects the owner against the use of inferior materials and poor workmanship.
7. It protects the contractor too, by defining exactly what he is obliged to do — and no more.
8. It fixes measurement and payment, and so avoids disputes over billing.
9. It records the intention for future maintenance, repair and valuation.
10. A tender paper without a specification is baseless — the contractor has nothing on which to build his rate, and the owner nothing against which to judge it.

b) Specification for stone masonry work in 1:6 mortar

Detailed specification — random rubble stone masonry in 1:6 cement sand mortar

1. Scope. Coursed or uncoursed random rubble stone masonry in walls, foundations and retaining walls, laid in 1:6 cement sand mortar.

2. Stone. Stone shall be hard, sound, durable and free from cracks, flaws, veins and weathered patches, obtained from an approved quarry. It shall be of uniform colour and texture and shall not absorb more than 5% of its dry weight of water in 24 hours. The crushing strength shall be not less than 200 kg/cm². Rounded and water-worn boulders shall not be used unless dressed. No stone shall be less than 150 mm in any direction, and the largest dimension shall not exceed three times the smallest.

3. Dressing. Stones shall be hammer dressed on the face, the sides and the beds, so that they fit closely and no hollow remains behind the face. Bushing on the face shall not project more than 40 mm.

4. Mortar. Cement sand mortar 1:6 by volume, prepared as specified for cement mortar — measured in standard boxes, mixed dry to a uniform colour, then mixed with the minimum water for workability, and used within 30 minutes.

5. Workmanship

• Stones shall be laid on their natural bed, wetted before laying, and well bedded and solidly packed in mortar; no stone shall be laid dry or hammered into place after the mortar has begun to set.
• The masonry shall be built in level courses throughout, and the height raised in one day shall not exceed 60 cm.
• Vertical joints shall break — no joint shall come over the joint below, and joints shall be staggered by at least 75 mm.
• Joints shall be completely filled with mortar and shall not exceed 20 mm in thickness.
• Through (bond) stones extending the full thickness of the wall shall be provided at not more than 1.5 m apart in every course, for walls up to 60 cm thick. For thicker walls, a line of overlapping bond stones shall be provided.
• Quoins at the corners shall be of selected larger stones, properly dressed square and laid header and stretcher alternately.
• Small stone chips and spalls may be used to fill the interstices, but shall not be used to support the stones nor to make up more than a reasonable part of the face.
• The face shall be kept true and in plumb, checked with a plumb bob and straight edge; the joints shall be raked to a depth of 20 mm where the work is to be plastered or pointed.

6. Curing. The masonry shall be kept constantly moist for at least 14 days, and protected from rain, sun and frost.

7. Measurement and payment. Measured in cubic metres (m³), separately in foundation, plinth and superstructure, and separately for each class of masonry and each mortar mix. No deduction for openings up to 0.1 m² or bearings up to 0.1 m³. Paid per m³, the rate including all materials, dressing, labour, scaffolding, curing and protection.

ENCE 351 §8.3 and §8.5.

Importance of specification in construction

1. It completes the drawing. A drawing gives dimensions only. Two buildings of identical drawings can differ enormously in cost and quality; the specification is what distinguishes them.
2. It is the legal backbone of the contract. In any dispute, the specification is the document to which both parties and the arbitrator turn.
3. It governs the rate. The analysis of rates begins from the specification; change the mix from 1:2:4 to 1:1½:3 and the rate changes at once.
4. It ensures fair competition. All tenderers price the same quality, so the lowest bid is genuinely the lowest.
5. It is the standard of acceptance. The engineer accepts or rejects work by comparing it with the specification.
6. It protects the owner against the use of inferior materials and poor workmanship.
7. It protects the contractor too, by defining exactly what he is obliged to do — and no more.
8. It fixes measurement and payment, and so avoids disputes over billing.
9. It records the intention for future maintenance, repair and valuation.
10. A tender paper without a specification is baseless — the contractor has nothing on which to build his rate, and the owner nothing against which to judge it.

Types of specification

Specifications are classified in two ways.

A. By the amount of detail

B. By the way the requirement is expressed

• Prescriptive (method) specification — states exactly what materials to use and how to do the work. The designer takes responsibility for the result.
• Performance specification — states the result to be achieved (for example, concrete of 20 N/mm² at 28 days) and leaves the means to the contractor, who then carries the responsibility.
• Proprietary specification — names a particular brand or manufacturer.
• Reference specification — refers to a published standard (IS, NS, ASTM, DoR / DUDBC standard specification) instead of repeating its text.
• Open and closed specifications — an open one allows equivalents, a closed one does not.

ENCE 351 §8.2 and §8.3.

a) Importance of specifications in construction works

Importance of specification in construction

1. It completes the drawing. A drawing gives dimensions only. Two buildings of identical drawings can differ enormously in cost and quality; the specification is what distinguishes them.
2. It is the legal backbone of the contract. In any dispute, the specification is the document to which both parties and the arbitrator turn.
3. It governs the rate. The analysis of rates begins from the specification; change the mix from 1:2:4 to 1:1½:3 and the rate changes at once.
4. It ensures fair competition. All tenderers price the same quality, so the lowest bid is genuinely the lowest.
5. It is the standard of acceptance. The engineer accepts or rejects work by comparing it with the specification.
6. It protects the owner against the use of inferior materials and poor workmanship.
7. It protects the contractor too, by defining exactly what he is obliged to do — and no more.
8. It fixes measurement and payment, and so avoids disputes over billing.
9. It records the intention for future maintenance, repair and valuation.
10. A tender paper without a specification is baseless — the contractor has nothing on which to build his rate, and the owner nothing against which to judge it.

b) The art and science of writing specifications

Writing a specification is a science in that it rests on codes, tested material properties and established methods of construction; it is an art in that it must express those requirements in language that is complete, unambiguous and enforceable, without becoming so rigid that the work cannot be built economically.

(i) Necessity of specification

• A drawing gives size and shape only; the quality of materials and workmanship can be conveyed only in words.
• It is a contract document, and therefore legally binding on both parties.
• The analysis of rates is impossible until the item is defined by its specification.
• It puts all tenderers on the same footing, making bids comparable.
• It is the standard of acceptance for the engineer and the guide for the contractor.
• It prevents disputes and fixes responsibility for quality.

(ii) Procedure of drafting

Procedure of drafting a specification

1. Study the drawings and the design intent, and list every item of work.
2. Study the site — what materials are locally available, what skills, what weather.
3. Refer to the standard specifications of the department (DUDBC, DoR, DWSS) and to the relevant IS / NS codes.
4. Arrange the items in the order of construction, grouped under sub-heads.
5. For each item, write in a fixed order: (a) scope, (b) materials, (c) proportion or mix, (d) workmanship and method, (e) curing and protection, (f) tests and tolerances, (g) mode of measurement and payment.
6. Number the clauses and cross-refer where needed.
7. Check against the bill of quantities and the drawings for consistency, and have it reviewed by a second engineer.

(iii) What to write and what to avoid

What to write, and what to avoid

Techniques / principles of writing a specification

1. Be clear and unambiguous. Use simple, direct language; one sentence should carry one requirement. Avoid words such as "good", "suitable", "proper", "best quality" — they are unenforceable.
2. Be complete. Cover material, proportion, workmanship, method, tolerance, testing, curing, protection, and the mode of measurement and payment.
3. Be brief. Say a thing once. Repetition creates contradiction.
4. Use the imperative or the word "shall" — "bricks shall be first class". "Should" and "may" are advisory and unenforceable.
5. Follow the sequence of construction — materials first, then workmanship, then measurement and payment.
6. Refer to standards (IS / NS codes) rather than reproducing them, but quote the number and the year.
7. Do not contradict the drawing or the conditions of contract; if there is a conflict, state which prevails.
8. Quantify wherever possible — give numbers, tolerances and limits, not adjectives. "Joints not exceeding 10 mm", not "thin joints".
9. Do not specify the impossible or the unavailable; the specification must be practicable at that site.
10. Do not encroach on the contractor's means unless the method genuinely matters — over-specifying transfers the risk back to the owner.
11. Write in a standard order and number the clauses, so that they can be referred to.
12. Check it against the bill of quantities, so that every item priced is specified and every item specified is priced.

ENCE 351 §8.3 and §8.4.

a) Method of writing specifications

Techniques / principles of writing a specification

1. Be clear and unambiguous. Use simple, direct language; one sentence should carry one requirement. Avoid words such as "good", "suitable", "proper", "best quality" — they are unenforceable.
2. Be complete. Cover material, proportion, workmanship, method, tolerance, testing, curing, protection, and the mode of measurement and payment.
3. Be brief. Say a thing once. Repetition creates contradiction.
4. Use the imperative or the word "shall" — "bricks shall be first class". "Should" and "may" are advisory and unenforceable.
5. Follow the sequence of construction — materials first, then workmanship, then measurement and payment.
6. Refer to standards (IS / NS codes) rather than reproducing them, but quote the number and the year.
7. Do not contradict the drawing or the conditions of contract; if there is a conflict, state which prevails.
8. Quantify wherever possible — give numbers, tolerances and limits, not adjectives. "Joints not exceeding 10 mm", not "thin joints".
9. Do not specify the impossible or the unavailable; the specification must be practicable at that site.
10. Do not encroach on the contractor's means unless the method genuinely matters — over-specifying transfers the risk back to the owner.
11. Write in a standard order and number the clauses, so that they can be referred to.
12. Check it against the bill of quantities, so that every item priced is specified and every item specified is priced.

Procedure of drafting a specification

1. Study the drawings and the design intent, and list every item of work.
2. Study the site — what materials are locally available, what skills, what weather.
3. Refer to the standard specifications of the department (DUDBC, DoR, DWSS) and to the relevant IS / NS codes.
4. Arrange the items in the order of construction, grouped under sub-heads.
5. For each item, write in a fixed order: (a) scope, (b) materials, (c) proportion or mix, (d) workmanship and method, (e) curing and protection, (f) tests and tolerances, (g) mode of measurement and payment.
6. Number the clauses and cross-refer where needed.
7. Check against the bill of quantities and the drawings for consistency, and have it reviewed by a second engineer.

b) Detailed specification for earthwork in excavation in sandy soil for isolated footings of a multi-storey building

Detailed specification — earthwork in excavation in sandy soil for isolated footings of a multi-storey building

1. Scope. Excavation in sandy soil for isolated column footings, including shoring, dewatering, disposal of surplus earth and refilling.

2. Setting out. The centre lines of the columns shall be set out accurately from the drawings and marked with pegs and lime, and referred to permanent reference pillars set clear of the excavation. The layout shall be checked and approved by the engineer before excavation begins. The existing ground level shall be jointly recorded before starting, as the basis of measurement.

3. Excavation

• Excavation shall be taken out to the exact dimensions and levels shown on the drawing, plus the authorised working space, and no more. Excavation beyond the authorised limits shall not be paid for, and shall be made good with concrete of the same grade as the footing at the contractor's cost.
• The sides shall be kept vertical where shored; where the soil does not stand, the sides shall be sloped at the angle of repose of the sand (about 30° to 34°) or the excavation shall be shored.
• Because sandy soil is cohesionless and liable to collapse, close timbering (sheet piling, or vertical poling boards with walings and struts covering the whole face) shall be provided for depths exceeding 1.5 m, and shall be maintained until the footing concrete has gained strength. Timbering shall be removed in stages as backfilling proceeds.
• Excavated material shall be stacked at least 1.0 m clear of the edge of the excavation, so as not to surcharge the sides.
• The last 100–150 mm shall be excavated by hand immediately before laying the levelling course, so that the bearing stratum is not disturbed or loosened. The bed shall be levelled, dressed and well rammed.
• Excavation for adjacent footings shall be carried out in a sequence that does not undermine any footing already cast or any adjoining structure.

4. Dewatering. Any water met with, from the water table, rain or any other source, shall be removed continuously by pumping or bailing so that the excavation is kept dry until the concrete has set. Sandy soil below the water table is liable to boiling and piping; where this occurs, well-point dewatering shall be adopted. Pumping shall not be done in a way that draws fines out of the surrounding soil.

5. Protection. The excavation shall be protected by barricades and warning lights. Surface water shall be prevented from entering by bunds or catch drains.

6. Refilling. After the footing and the column up to plinth level have been cast and cured, the space around shall be refilled with approved excavated earth free from vegetation, rubbish and clods, in layers not exceeding 150–200 mm, each layer watered and well rammed to the required density. Surplus earth shall be carried away and disposed of as directed within the specified lead.

7. Measurement and payment. Excavation shall be measured in cubic metres (m³) of the authorised dimensions — number × length × breadth × depth — measured from the recorded original ground level. It shall be measured separately for each class of soil and in depth stages (the first 1.5 m, and each subsequent 1.5 m), and separately below the water table. Lead beyond 30 m and lift beyond 1.5 m shall be paid extra. Shoring, timbering and dewatering shall be paid as separate items where so provided in the bill of quantities, failing which they shall be deemed included in the rate. Payment shall be per m³.

ENCE 351 §8.4 and §8.5.

a) Importance of specification, and the main techniques of writing one

Importance of specification in construction

1. It completes the drawing. A drawing gives dimensions only. Two buildings of identical drawings can differ enormously in cost and quality; the specification is what distinguishes them.
2. It is the legal backbone of the contract. In any dispute, the specification is the document to which both parties and the arbitrator turn.
3. It governs the rate. The analysis of rates begins from the specification; change the mix from 1:2:4 to 1:1½:3 and the rate changes at once.
4. It ensures fair competition. All tenderers price the same quality, so the lowest bid is genuinely the lowest.
5. It is the standard of acceptance. The engineer accepts or rejects work by comparing it with the specification.
6. It protects the owner against the use of inferior materials and poor workmanship.
7. It protects the contractor too, by defining exactly what he is obliged to do — and no more.
8. It fixes measurement and payment, and so avoids disputes over billing.
9. It records the intention for future maintenance, repair and valuation.
10. A tender paper without a specification is baseless — the contractor has nothing on which to build his rate, and the owner nothing against which to judge it.

Techniques / principles of writing a specification

1. Be clear and unambiguous. Use simple, direct language; one sentence should carry one requirement. Avoid words such as "good", "suitable", "proper", "best quality" — they are unenforceable.
2. Be complete. Cover material, proportion, workmanship, method, tolerance, testing, curing, protection, and the mode of measurement and payment.
3. Be brief. Say a thing once. Repetition creates contradiction.
4. Use the imperative or the word "shall" — "bricks shall be first class". "Should" and "may" are advisory and unenforceable.
5. Follow the sequence of construction — materials first, then workmanship, then measurement and payment.
6. Refer to standards (IS / NS codes) rather than reproducing them, but quote the number and the year.
7. Do not contradict the drawing or the conditions of contract; if there is a conflict, state which prevails.
8. Quantify wherever possible — give numbers, tolerances and limits, not adjectives. "Joints not exceeding 10 mm", not "thin joints".
9. Do not specify the impossible or the unavailable; the specification must be practicable at that site.
10. Do not encroach on the contractor's means unless the method genuinely matters — over-specifying transfers the risk back to the owner.
11. Write in a standard order and number the clauses, so that they can be referred to.
12. Check it against the bill of quantities, so that every item priced is specified and every item specified is priced.

b) (i) Detailed specification of RCC with M20 concrete in columns

Detailed specification — RCC with M20 concrete in columns

1. Scope. Reinforced cement concrete of grade M20 (nominal mix 1:1½:3) in columns, including formwork, placing, compaction, finishing and curing. Reinforcement is measured and paid separately.

2. Materials

• Cement — ordinary Portland cement conforming to the relevant IS / NS standard, fresh and free from lumps.
• Fine aggregate — clean, sharp river sand, free from clay, silt, salt and organic matter, silt content not exceeding 4%, conforming to grading zone II or III.
• Coarse aggregate — hard, dense, durable crushed stone, angular, free from dust, flaky and elongated particles, of nominal maximum size 20 mm (and not exceeding one-fourth of the least dimension of the member, nor the clear cover, nor the minimum clear spacing between bars).
• Water — clean and fit for drinking; pH not less than 6.
• Steel — deformed bars of the specified grade, free from rust, scale, oil and grease.

3. Proportioning and mixing. Cement, fine and coarse aggregate shall be proportioned 1 : 1½ : 3 by volume using standard boxes, cement being taken by the bag. The water cement ratio shall not exceed 0.50, and shall be adjusted for the moisture in the aggregate. Mixing shall be done in a mechanical mixer for not less than 2 minutes after all the materials are in, until the mix is uniform in colour and consistency. Hand mixing is permitted only for small quantities and with 10% extra cement. The slump shall be 25–75 mm for columns.

4. Formwork. Formwork shall be of steel or well-seasoned timber, sufficiently rigid to retain its shape, with tight joints to prevent leakage of grout. It shall be truly vertical, properly braced and supported, and its inner surface treated with an approved mould oil before the reinforcement is placed. Formwork to the sides of columns shall not be removed earlier than 24–48 hours after casting.

5. Reinforcement. Bars shall be cut, bent and fixed strictly to the bar bending schedule, tied at every intersection with 18 SWG annealed binding wire, and held in position by cover blocks of the same mix. The clear cover to the main reinforcement in a column shall be 40 mm, and not less than the diameter of the bar. Laps shall be staggered and shall be as specified; laps in adjacent bars shall not occur at the same section.

6. Placing and compaction

• Concrete shall be placed within 30 minutes of mixing and before the initial set has begun.
• It shall be deposited as near as possible to its final position, and shall not be dropped from a height exceeding 1.5 m, to prevent segregation.
• It shall be placed in horizontal layers not exceeding 300 mm and compacted with a needle (immersion) vibrator until air bubbles cease to rise and the surface shows a thin film of mortar. Over-vibration causing segregation shall be avoided.
• Concreting of a column shall be carried out in one continuous operation up to the underside of the beam. Where a construction joint is unavoidable, it shall be made at a position approved by the engineer, roughened, cleaned of laitance and wetted, and a coat of cement slurry applied before fresh concrete is placed.

7. Curing. Curing shall begin as soon as the concrete has hardened sufficiently, and shall continue for at least 14 days by wrapping with wet gunny bags or hessian kept continuously moist. The concrete shall be protected from rain, direct sun, running water and mechanical damage during this period.

8. Tests. Cube tests shall be carried out on 150 mm cubes as specified; the characteristic compressive strength at 28 days shall be 20 N/mm². Slump shall be tested at the point of placing. The frequency of sampling shall be as required by the code.

9. Measurement and payment. RCC work shall be measured in cubic metres (m³) of the finished concrete. No deduction is made for the volume of the reinforcement, nor for openings up to 0.1 m² or embedded pipes up to 100 cm² in sectional area. Formwork is measured separately in m² of the surface in contact with the concrete, and reinforcement separately in kg (weight per metre = d²/162). Payment shall be per m³ at the rate quoted, which includes materials, mixing, placing, compaction, finishing and curing.

b) (ii) Detailed specification of brick work in 1:6 cement sand mortar

Detailed specification — first class brickwork in cement sand mortar

1. Scope. This specification covers first class brickwork in walls, piers and similar work, laid in cement sand mortar of the proportion stated in the item.

2. Materials

• Bricks shall be first class, table moulded, thoroughly burnt in a kiln, of uniform deep red, cherry or copper colour, free from cracks, chips, flaws and lumps of lime or organic matter. They shall have sharp, straight and square edges, plane faces and uniform size, and shall give a clear metallic ringing sound when struck against one another. The minimum crushing strength shall be 105 kg/cm² (10.5 N/mm²), and a dry brick shall not absorb more than one-sixth of its weight after one hour's immersion (about 20% of the dry weight after 24 hours). Bricks shall not break when dropped flat on hard ground from about 1 m.
• Cement shall be ordinary Portland cement conforming to the relevant IS / NS standard, fresh, free from lumps, and stored clear of the ground and damp.
• Sand shall be clean, sharp, coarse river sand, free from clay, silt, salt and organic matter; silt content not more than 4%. It shall be screened and washed if necessary.
• Water shall be clean and fit for drinking, free from oil, acid, alkali and organic matter.

3. Mortar. Cement and sand shall be measured by boxes of standard size in the proportion stated in the item, mixed dry on a clean watertight platform until the mixture is of uniform colour, and then mixed with the minimum water necessary to give a workable consistency. Only so much mortar shall be prepared as can be used within 30 minutes of adding water. Mortar left unused beyond its initial setting time shall be rejected; re-tempering is not permitted.

4. Soaking. Bricks shall be fully soaked in clean water for at least two hours — and for first class work four hours — before use, stacked on clean wooden planks clear of mud, and allowed to become surface-dry before laying, so that they neither absorb water from the mortar nor float on it.

5. Workmanship

• Brickwork shall be laid in English bond unless otherwise specified, this being the strongest bond, with alternate courses of headers and stretchers and a queen closer next to the quoin header.
• Bricks shall be laid with their frogs upward, on a full bed of mortar, and well pressed so that the mortar is squeezed out and the joint is completely filled.
• Joints shall be full and shall not exceed 6 mm in cement mortar or 10 mm in lime mortar. Vertical joints must break — that is, they shall not come one above the other in consecutive courses.
• No bats shall be used except where they are absolutely required to obtain the specified bond or the dimensions of a course.
• Each course shall be truly horizontal and the face truly vertical, checked with a spirit level and plumb bob. The work shall be taken up in level courses all round.
• The height raised in one day shall not exceed 1.0 m, to avoid unequal settlement of the fresh work.
• Where the work has to be left, it shall be stepped or raked back at an angle not steeper than 45°; toothing shall not be allowed.
• The face of the wall shall be kept clean of mortar droppings. Where the surface is to be plastered, the joints shall be raked out to a depth of 12–15 mm while the mortar is green, to give a key to the plaster; where it is to be pointed, the joints shall be raked as required for pointing.
• Openings, chases, holdfasts and embedded fixtures shall be provided as the work proceeds; cutting afterwards is not permitted.

6. Curing. The work shall be kept constantly moist on all faces for at least 10 to 14 days, by sprinkling water at least twice a day and by covering with wet gunny bags. At the end of each day's work a trough at least 2.5 cm deep shall be formed on the top of the wall with weak mortar or mud edging and kept flooded with water. Freshly laid work shall be protected from rain, sun and frost; during rain no brickwork shall be carried out unless it can be protected for 24 hours.

7. Scaffolding. Single scaffolding may be used for ordinary work; double scaffolding shall be used for important work and where the wall face is to be exposed, so that no hole is left in the finished face.

8. Measurement and payment. Brickwork shall be measured in cubic metres (m³), the dimensions being taken to the nearest 0.01 m. No deduction is made for the bearings of lintels and beams up to 0.1 m³ in volume, nor for openings up to 0.1 m² in area. Brickwork of each thickness, each class of brick and each mortar mix shall be measured separately, and separately in foundation, in plinth and in superstructure. Payment shall be made per m³ at the rate quoted, which shall include all materials, labour, scaffolding, curing and protection.

For 1 m³ of wet 1:6 cement sand mortar, taking a dry volume factor of 1.30: cement = 1.30 × (1/7) = 0.1857 m³ = 267.4 kg = 5.35 bags, and sand = 1.30 × (6/7) = 1.114 m³. About 500 bricks and 0.25–0.30 m³ of mortar are needed per m³ of brickwork.

ENCE 351 §8.3, §8.4 and §8.5.

a) What a detailed specification is

A detailed specification describes one item of work completely — the materials and their quality, the proportion of the mix, the workmanship and method of execution, the curing, the tests, and the mode of measurement and payment. It forms part of the contract and is the standard by which the work is accepted and paid for.

b) Detailed specification of first class brick work in 1:6 cement sand mortar

Detailed specification — first class brickwork in cement sand mortar

1. Scope. This specification covers first class brickwork in walls, piers and similar work, laid in cement sand mortar of the proportion stated in the item.

2. Materials

• Bricks shall be first class, table moulded, thoroughly burnt in a kiln, of uniform deep red, cherry or copper colour, free from cracks, chips, flaws and lumps of lime or organic matter. They shall have sharp, straight and square edges, plane faces and uniform size, and shall give a clear metallic ringing sound when struck against one another. The minimum crushing strength shall be 105 kg/cm² (10.5 N/mm²), and a dry brick shall not absorb more than one-sixth of its weight after one hour's immersion (about 20% of the dry weight after 24 hours). Bricks shall not break when dropped flat on hard ground from about 1 m.
• Cement shall be ordinary Portland cement conforming to the relevant IS / NS standard, fresh, free from lumps, and stored clear of the ground and damp.
• Sand shall be clean, sharp, coarse river sand, free from clay, silt, salt and organic matter; silt content not more than 4%. It shall be screened and washed if necessary.
• Water shall be clean and fit for drinking, free from oil, acid, alkali and organic matter.

3. Mortar. Cement and sand shall be measured by boxes of standard size in the proportion stated in the item, mixed dry on a clean watertight platform until the mixture is of uniform colour, and then mixed with the minimum water necessary to give a workable consistency. Only so much mortar shall be prepared as can be used within 30 minutes of adding water. Mortar left unused beyond its initial setting time shall be rejected; re-tempering is not permitted.

4. Soaking. Bricks shall be fully soaked in clean water for at least two hours — and for first class work four hours — before use, stacked on clean wooden planks clear of mud, and allowed to become surface-dry before laying, so that they neither absorb water from the mortar nor float on it.

5. Workmanship

• Brickwork shall be laid in English bond unless otherwise specified, this being the strongest bond, with alternate courses of headers and stretchers and a queen closer next to the quoin header.
• Bricks shall be laid with their frogs upward, on a full bed of mortar, and well pressed so that the mortar is squeezed out and the joint is completely filled.
• Joints shall be full and shall not exceed 6 mm in cement mortar or 10 mm in lime mortar. Vertical joints must break — that is, they shall not come one above the other in consecutive courses.
• No bats shall be used except where they are absolutely required to obtain the specified bond or the dimensions of a course.
• Each course shall be truly horizontal and the face truly vertical, checked with a spirit level and plumb bob. The work shall be taken up in level courses all round.
• The height raised in one day shall not exceed 1.0 m, to avoid unequal settlement of the fresh work.
• Where the work has to be left, it shall be stepped or raked back at an angle not steeper than 45°; toothing shall not be allowed.
• The face of the wall shall be kept clean of mortar droppings. Where the surface is to be plastered, the joints shall be raked out to a depth of 12–15 mm while the mortar is green, to give a key to the plaster; where it is to be pointed, the joints shall be raked as required for pointing.
• Openings, chases, holdfasts and embedded fixtures shall be provided as the work proceeds; cutting afterwards is not permitted.

6. Curing. The work shall be kept constantly moist on all faces for at least 10 to 14 days, by sprinkling water at least twice a day and by covering with wet gunny bags. At the end of each day's work a trough at least 2.5 cm deep shall be formed on the top of the wall with weak mortar or mud edging and kept flooded with water. Freshly laid work shall be protected from rain, sun and frost; during rain no brickwork shall be carried out unless it can be protected for 24 hours.

7. Scaffolding. Single scaffolding may be used for ordinary work; double scaffolding shall be used for important work and where the wall face is to be exposed, so that no hole is left in the finished face.

8. Measurement and payment. Brickwork shall be measured in cubic metres (m³), the dimensions being taken to the nearest 0.01 m. No deduction is made for the bearings of lintels and beams up to 0.1 m³ in volume, nor for openings up to 0.1 m² in area. Brickwork of each thickness, each class of brick and each mortar mix shall be measured separately, and separately in foundation, in plinth and in superstructure. Payment shall be made per m³ at the rate quoted, which shall include all materials, labour, scaffolding, curing and protection.

For 1 m³ of wet 1:6 mortar: cement = 1.30 × (1/7) = 0.1857 m³ = 267.4 kg = 5.35 bags; sand = 1.30 × (6/7) = 1.114 m³. One cubic metre of brickwork takes about 500 bricks and 0.25–0.30 m³ of mortar.

ENCE 351 §8.5.

a) Importance of specification in construction work

Importance of specification in construction

1. It completes the drawing. A drawing gives dimensions only. Two buildings of identical drawings can differ enormously in cost and quality; the specification is what distinguishes them.
2. It is the legal backbone of the contract. In any dispute, the specification is the document to which both parties and the arbitrator turn.
3. It governs the rate. The analysis of rates begins from the specification; change the mix from 1:2:4 to 1:1½:3 and the rate changes at once.
4. It ensures fair competition. All tenderers price the same quality, so the lowest bid is genuinely the lowest.
5. It is the standard of acceptance. The engineer accepts or rejects work by comparing it with the specification.
6. It protects the owner against the use of inferior materials and poor workmanship.
7. It protects the contractor too, by defining exactly what he is obliged to do — and no more.
8. It fixes measurement and payment, and so avoids disputes over billing.
9. It records the intention for future maintenance, repair and valuation.
10. A tender paper without a specification is baseless — the contractor has nothing on which to build his rate, and the owner nothing against which to judge it.

b) Detailed specification for cement sand mortar 1:6

Detailed specification — cement sand mortar 1:6

1. Scope. Cement sand mortar of proportion 1:6 by volume, for use in masonry and allied work.

2. Cement. Ordinary Portland cement conforming to the relevant IS / NS standard, fresh, free from lumps, and stored on a raised platform clear of the ground and protected from damp. Cement more than three months old shall be tested before use.

3. Sand. Clean, sharp, coarse river sand, free from clay, silt, salt, mica and organic matter, with silt content not exceeding 4%, and well graded. It shall be screened and, if necessary, washed. The fineness modulus shall be within the limits specified for masonry mortar.

4. Water. Clean and fit for drinking, free from oil, acid, alkali, salt and organic matter.

5. Proportioning. One part of cement to six parts of sand by volume. Measurement shall be by standard measuring boxes of size 30 × 30 × 38 cm (0.0342 m³), which corresponds to one bag of cement of 50 kg. Cement shall be measured by the bag; sand shall be measured loose in boxes, and an allowance made for bulking if the sand is damp.

6. Mixing

• Mixing shall be done on a clean, watertight platform or in a mechanical mixer.
• The measured cement and sand shall first be mixed dry, turning at least three times, until the mixture is of uniform colour throughout.
• Water shall then be added gradually, and the whole mixed thoroughly to a stiff, workable and uniform consistency — not so wet that it flows. In no case shall the water exceed 30 litres per 50 kg bag of cement.
• Only so much mortar shall be prepared as can be used within 30 minutes of adding water.
• Mortar which has begun to set shall be rejected and removed from the site. Re-tempering — adding water to stiffened mortar — is strictly prohibited.

7. Quantities. For 1 m³ of wet 1:6 cement sand mortar, taking a dry volume factor of 1.30:

8. Measurement and payment. Mortar is normally not measured separately — its cost is included in the rate of the masonry, plastering or pointing in which it is used. Where it is required to be measured as a separate item, it shall be measured in m³ of the finished wet mortar and paid per m³.

ENCE 351 §8.3 and §8.5.

a) Importance of specification

Importance of specification in construction

1. It completes the drawing. A drawing gives dimensions only. Two buildings of identical drawings can differ enormously in cost and quality; the specification is what distinguishes them.
2. It is the legal backbone of the contract. In any dispute, the specification is the document to which both parties and the arbitrator turn.
3. It governs the rate. The analysis of rates begins from the specification; change the mix from 1:2:4 to 1:1½:3 and the rate changes at once.
4. It ensures fair competition. All tenderers price the same quality, so the lowest bid is genuinely the lowest.
5. It is the standard of acceptance. The engineer accepts or rejects work by comparing it with the specification.
6. It protects the owner against the use of inferior materials and poor workmanship.
7. It protects the contractor too, by defining exactly what he is obliged to do — and no more.
8. It fixes measurement and payment, and so avoids disputes over billing.
9. It records the intention for future maintenance, repair and valuation.
10. A tender paper without a specification is baseless — the contractor has nothing on which to build his rate, and the owner nothing against which to judge it.

b) Detailed specification of brick work in cement sand mortar

Detailed specification — first class brickwork in cement sand mortar

1. Scope. This specification covers first class brickwork in walls, piers and similar work, laid in cement sand mortar of the proportion stated in the item.

2. Materials

• Bricks shall be first class, table moulded, thoroughly burnt in a kiln, of uniform deep red, cherry or copper colour, free from cracks, chips, flaws and lumps of lime or organic matter. They shall have sharp, straight and square edges, plane faces and uniform size, and shall give a clear metallic ringing sound when struck against one another. The minimum crushing strength shall be 105 kg/cm² (10.5 N/mm²), and a dry brick shall not absorb more than one-sixth of its weight after one hour's immersion (about 20% of the dry weight after 24 hours). Bricks shall not break when dropped flat on hard ground from about 1 m.
• Cement shall be ordinary Portland cement conforming to the relevant IS / NS standard, fresh, free from lumps, and stored clear of the ground and damp.
• Sand shall be clean, sharp, coarse river sand, free from clay, silt, salt and organic matter; silt content not more than 4%. It shall be screened and washed if necessary.
• Water shall be clean and fit for drinking, free from oil, acid, alkali and organic matter.

3. Mortar. Cement and sand shall be measured by boxes of standard size in the proportion stated in the item, mixed dry on a clean watertight platform until the mixture is of uniform colour, and then mixed with the minimum water necessary to give a workable consistency. Only so much mortar shall be prepared as can be used within 30 minutes of adding water. Mortar left unused beyond its initial setting time shall be rejected; re-tempering is not permitted.

4. Soaking. Bricks shall be fully soaked in clean water for at least two hours — and for first class work four hours — before use, stacked on clean wooden planks clear of mud, and allowed to become surface-dry before laying, so that they neither absorb water from the mortar nor float on it.

5. Workmanship

• Brickwork shall be laid in English bond unless otherwise specified, this being the strongest bond, with alternate courses of headers and stretchers and a queen closer next to the quoin header.
• Bricks shall be laid with their frogs upward, on a full bed of mortar, and well pressed so that the mortar is squeezed out and the joint is completely filled.
• Joints shall be full and shall not exceed 6 mm in cement mortar or 10 mm in lime mortar. Vertical joints must break — that is, they shall not come one above the other in consecutive courses.
• No bats shall be used except where they are absolutely required to obtain the specified bond or the dimensions of a course.
• Each course shall be truly horizontal and the face truly vertical, checked with a spirit level and plumb bob. The work shall be taken up in level courses all round.
• The height raised in one day shall not exceed 1.0 m, to avoid unequal settlement of the fresh work.
• Where the work has to be left, it shall be stepped or raked back at an angle not steeper than 45°; toothing shall not be allowed.
• The face of the wall shall be kept clean of mortar droppings. Where the surface is to be plastered, the joints shall be raked out to a depth of 12–15 mm while the mortar is green, to give a key to the plaster; where it is to be pointed, the joints shall be raked as required for pointing.
• Openings, chases, holdfasts and embedded fixtures shall be provided as the work proceeds; cutting afterwards is not permitted.

6. Curing. The work shall be kept constantly moist on all faces for at least 10 to 14 days, by sprinkling water at least twice a day and by covering with wet gunny bags. At the end of each day's work a trough at least 2.5 cm deep shall be formed on the top of the wall with weak mortar or mud edging and kept flooded with water. Freshly laid work shall be protected from rain, sun and frost; during rain no brickwork shall be carried out unless it can be protected for 24 hours.

7. Scaffolding. Single scaffolding may be used for ordinary work; double scaffolding shall be used for important work and where the wall face is to be exposed, so that no hole is left in the finished face.

8. Measurement and payment. Brickwork shall be measured in cubic metres (m³), the dimensions being taken to the nearest 0.01 m. No deduction is made for the bearings of lintels and beams up to 0.1 m³ in volume, nor for openings up to 0.1 m² in area. Brickwork of each thickness, each class of brick and each mortar mix shall be measured separately, and separately in foundation, in plinth and in superstructure. Payment shall be made per m³ at the rate quoted, which shall include all materials, labour, scaffolding, curing and protection.

ENCE 351 §8.3 and §8.5.