3.1 Preparation of Specifications

The preparation of specifications is a critical step in the measurement and costing process, providing detailed descriptions of the materials, workmanship, and quality standards necessary for the project. In Kenya, civil engineers must ensure that specifications comply with local standards, client requirements, and industry best practices. Specifications must be clear, unambiguous, and easily cross-referenced with project drawings to avoid disputes and cost overruns.

3.1.1 Specifications preparations

Specification preparation involves creating detailed written instructions that describe the materials, workmanship, and methods required for each part of the construction work. This ensures all parties have a common understanding of the project requirements, thereby facilitating accurate measurement and costing.

Concept and Purpose

Specifications communicate the technical requirements for construction works, guiding contractors on acceptable materials, workmanship, and quality control measures.

• Ensures Quality Control: Specifications define minimum standards to maintain consistent quality throughout the project.
• Facilitates Accurate Costing: Clear specifications enable quantity surveyors to prepare precise BoQs and cost estimates.
• Reduces Ambiguity: Detailed descriptions prevent misunderstandings between clients, contractors, and consultants.
• Supports Contract Administration: Specifications provide a basis for inspection, testing, and acceptance of works.
• Enhances Procurement: They guide suppliers and contractors on the required materials and workmanship, ensuring suitable procurement.

Steps in Preparing Specifications

1. Review Project Drawings and Scope: Understand the design intent and project requirements to develop relevant specifications.
2. Identify Materials and Workmanship Standards: Select appropriate materials and workmanship standards aligned with Kenyan codes and client needs.
3. Organize Specifications by Work Sections: Group specifications according to construction elements such as concrete, masonry, finishes, etc.
4. Write Clear Descriptions: Use unambiguous language to describe materials, methods, and quality expectations.
5. Include Testing and Inspection Requirements: Specify procedures for quality control and acceptance criteria.
6. Cross-check with Stakeholders: Verify specifications with design engineers and clients to ensure completeness and accuracy.

Types of Specifications

• Performance Specifications: Define the required performance criteria without prescribing methods.
• Prescriptive Specifications: Specify exact materials, workmanship, and methods to be followed.
• Proprietary Specifications: Name specific products or manufacturers to be used.
• Reference Specifications: Refer to established standards or codes for requirements.
• Combined Specifications: Mix performance and prescriptive clauses, for example stating a required concrete strength while also specifying minimum cement content.

Common Challenges in Specification Preparation

• Overly Vague Descriptions: Leading to contractor misunderstandings and potential disputes.
• Excessive Detail: Causing confusion and unnecessary restrictions.
• Incompatibility with Drawings: Resulting in conflicts between written and graphical information.
• Ignoring Local Standards: Leading to non-compliance with Kenyan regulations.
• Failure to Update Specifications: Causing outdated requirements and project delays.

3.1.1.1 Material

A material specification is the part of the specification that states exactly what materials and products must be used in the works, including their type, quality, grade, size, standard, source, testing, delivery and storage. It allows the quantity surveyor to price the bill of quantities correctly, the contractor to buy the right materials, and the engineer or clerk of works to accept or reject materials delivered to site. Material clauses usually refer to recognised standards, such as Kenya Standards (KS) issued by KEBS or British and European standards, and they state that materials must be new, of the best quality of their kind and approved before use. Example: the specification for a maternity wing at a mission hospital in Kapsabet required cement complying with the relevant Kenya Standard, clean washed river sand and 20 mm crushed ballast from an approved quarry, so that every contractor priced the same materials.

Information Included in a Material Specification

• Type and description: The exact material, such as ordinary Portland cement, high-yield deformed bars or machine-cut stone.
• Grade, class or strength: The required performance level, such as class 25 concrete or grade 500 reinforcement.
• Size and dimensions: Sizes, thicknesses, gauges or grading, such as 200 mm walling stone or 28-gauge roofing sheets.
• Standard to be complied with: The KS, BS or EN standard that the material must meet.
• Source and approval: Approved sources, suppliers or quarries, and whether samples must be approved before ordering.
• Testing and certification: Tests required and test certificates or KEBS marks to be provided.
• Delivery, handling and storage: How materials are to be delivered, protected and stored on site.
• Alternatives: Whether alternatives "or equal approved" are allowed and how they are approved.

Example Material Specification Clauses

Steps for Writing a Material Specification

1. List all materials: Identify every material shown on the drawings and in the bill of quantities.
2. Determine performance needs: Decide the strength, durability and appearance each material must achieve.
3. Select applicable standards: Identify the KS, BS or EN standards that each material must comply with.
4. State grades and sizes: Write the exact grade, class, size and dimensions required.
5. Specify sampling and testing: State the samples, tests and certificates required before and during use.
6. Specify delivery and storage: State how materials must be delivered, handled and stored to prevent damage.
7. State approval procedures: Describe how samples and alternatives will be approved.
8. Check against drawings and BoQ: Ensure the material descriptions agree with the drawings and bill items.

3.1.1.2 Workmanship

A workmanship specification is the part of the specification that describes how the work must be carried out, including the methods, sequence, skill, accuracy, tolerances, curing, protection and finishing required for each trade. While the material specification ensures the right materials are bought, the workmanship specification ensures that they are put together correctly, because even the best materials fail if they are poorly mixed, placed, fixed or protected. Workmanship clauses also state how completed work will be inspected and tested, and what happens if it does not comply. Example: the specification for a dormitory block at a girls' secondary school in Kakamega required blockwork to be laid in stretcher bond with 10 mm joints, hoop iron every third course and curing for seven days, which the clerk of works used to inspect every wall.

Information Included in a Workmanship Specification

• Methods of construction: How each operation is to be done, such as mixing, placing and compacting concrete.
• Sequence of work: The order in which operations must be carried out, such as damp-proof course before walling above.
• Accuracy and tolerances: Allowable deviations in level, line, plumb and dimensions.
• Curing and protection: How fresh work must be cured and protected from weather and damage.
• Skill and supervision: Requirements for skilled tradespeople and competent supervision.
• Inspection and testing: Stages at which work must be inspected and tests carried out.
• Making good and cleaning: Requirements for repairing defects and leaving work clean.
• Removal of defective work: The contractor's obligation to remove and replace work that does not comply.

Example Workmanship Specification Clauses

Steps for Writing a Workmanship Specification

1. Identify the work sections: List the trades involved, such as excavation, concrete, masonry, roofing and finishes.
2. Describe each operation: Write clear instructions for how each operation must be carried out.
3. State the sequence: Specify the order of operations and any hold points before the next stage.
4. Set tolerances: State the allowable deviations in line, level, plumb and dimensions.
5. Specify curing and protection: State how and for how long work must be cured and protected.
6. Specify inspection and testing: State inspection stages, tests and acceptance criteria.
7. State remedies for defects: Explain how defective work will be dealt with.
8. Review with the design team: Confirm the clauses agree with the drawings, design assumptions and contract conditions.

3.1.2 Following SMM/CESMM standards

In Kenya, adherence to internationally recognized standards such as the Standard Method of Measurement (SMM) and the Civil Engineering Standard Method of Measurement (CESMM) ensures uniformity and professionalism in specifications and BoQ preparation. These standards provide systematic rules and terminology for measuring construction works. Example: the quantity surveyor preparing tender documents for a SACCO office block in Nyeri used the SMM to describe and measure the building works, while the consultant for a county water pipeline used the CESMM for the trenching, pipelaying and manholes, so that every bidder priced identical items.

Overview of SMM and CESMM

• Standard Method of Measurement (SMM): Primarily used for building works, it provides standardized rules for measuring quantities and preparing BoQs.
• Civil Engineering Standard Method of Measurement (CESMM): Designed for civil engineering projects, it covers earthworks, roads, drainage, and other infrastructure works.
• Purpose: Both standards aim to promote clarity, reduce disputes, and facilitate fair tendering by standardizing measurement and description procedures.
• Application in Kenya: These standards are widely adopted by government agencies, private sector clients, and consultants to ensure consistency.
• Regular Updates: Both SMM and CESMM are periodically revised to incorporate new materials, methods, and technologies.

Key Features of SMM/CESMM

• Uniform Terminology: Clear definitions of work items and measurement rules.
• Item Description Format: Standardized phrasing for work items to facilitate comprehension.
• Measurement Rules: Specific guidance on how to measure quantities for different types of work, such as net measurement of work as fixed in place.
• Units of Measurement: Standard units for each item, such as m³ for excavation and concrete, m² for walling and finishes, m for pipes and kerbs, and kg or tonnes for reinforcement.
• Coverage Rules: Statements of what each item is deemed to include, such as labour, materials, plant, waste and fixing.

Steps for Applying SMM/CESMM When Preparing Descriptions

1. Identify the correct standard: Use the SMM for building works and the CESMM for civil engineering works, as stated in the contract.
2. Classify the work: Place each item in the correct work section or class, such as excavation, concrete or masonry.
3. Measure using the rules: Take dimensions from the drawings and measure them according to the standard's rules.
4. Use the correct units: State each quantity in the unit required by the standard.
5. Write the description: Describe each item using the standard's terminology and include the specification reference.
6. Check coverage: Confirm that what the item includes matches the standard's coverage rules.
7. Review the bill: Check the bill for completeness and consistency before issuing it for tender.

Benefits of Using SMM/CESMM

• Improved Accuracy: Reduces errors in measurement and costing.
• Facilitated Tendering: Enables contractors to prepare competitive and comparable bids.
• Enhanced Communication: Standard language improves clarity among stakeholders.
• Dispute Reduction: Clear measurement and description reduce claims and disagreements.
• Professional Recognition: Aligns with international best practices, enhancing project credibility.

Implementation Challenges

• Training Requirements: Professionals need adequate training to apply standards correctly.
• Project-Specific Adaptations: Some projects require modifications of standard rules.
• Integration with Local Regulations: Harmonizing standards with Kenyan building codes.
• Updating Documentation: Ensuring all project documents reflect current standards.
• Software Compatibility: Adapting standards for use in digital measurement and costing tools.

3.1.3 Cross-referencing with drawings and designs

Cross-referencing specifications with project drawings and designs is essential to ensure consistency and completeness in the BoQ. Drawings provide the graphical representation of the project, while specifications describe the qualitative requirements. Example: while preparing the bill for a hotel extension in Nanyuki, the quantity surveyor found that the drawings showed 150 mm floor slabs while the specification described 125 mm slabs, and the discrepancy was resolved with the engineer before tender, avoiding a costly variation.

Importance of Cross-Referencing

• Ensures Completeness: Confirms all elements shown in drawings are specified.
• Avoids Contradictions: Detects discrepancies between graphical and written information.
• Facilitates Accurate Measurement: Clarifies dimensions and quantities for BoQ preparation.
• Supports Quality Assurance: Aligns quality expectations with design intent.
• Simplifies Communication: Provides a clear reference framework for contractors and inspectors.

Methods of Cross-Referencing

• Using Item Numbers: Linking specification items with drawing references and codes.
• Referencing Drawing Sheets: Citing specific drawing numbers and details in specifications.
• Incorporating Detail Callouts: Ensuring detailed drawings correspond to specification sections.
• Creating Cross-Reference Tables: Tabulating specification clauses against drawing elements.
• Digital Integration: Employing software tools to link drawings and specifications electronically.

Steps to Cross-Reference Effectively

1. Review All Drawings Thoroughly: Identify all elements requiring specification.
2. Match Specification Sections to Drawings: Align each specification item with corresponding drawings.
3. Note Discrepancies and Resolve: Communicate with design team to clarify inconsistencies.
4. Update Specifications or Drawings: Amend documents to ensure mutual consistency.
5. Document Cross-Reference Links: Maintain records for easy navigation and verification.
6. Verify During Tendering and Execution: Use cross-references to check contractor queries and site works.

Challenges in Cross-Referencing

• Complex or Incomplete Drawings: Leading to gaps in specification coverage.
• Frequent Design Changes: Causing misalignment between documents.
• Poor Communication: Between design and specification teams.
• Lack of Standardized Referencing System: Resulting in confusion and errors.
• Time Constraints: Rushing cross-referencing can cause overlooked discrepancies.

Chapter Summary

This chapter focused on the preparation of the bill of quantities, starting with the development of clear and detailed specifications that cover both materials and workmanship, ensuring alignment with SMM and CESMM standards. It emphasized the importance of cross-referencing specifications with drawings and designs to maintain accuracy and consistency. The chapter then addressed the preparation of the schedule of rates, detailing how to calculate rates from abstracted quantities while applying standard costing guidelines. Attention was given to maintaining accuracy in costing and making necessary adjustments to rates based on specific project constraints. Finally, the chapter covered the compilation of the bill of quantities itself, highlighting the need for it to be comprehensive, accurate, and formatted according to standard practices. The process concludes with a thorough review of the bill of quantities to ensure consistency with the prepared specifications.