Five essential tips for writing effective specifications

A well-written and robust specification is vital to the success of construction projects. It is the document that details the product quality, the execution requirements, and the tasks and documentation that verify the intended outcomes. This article outlines five essential tips for writing and developing specifications, drawing upon experience from NBS, consultancy service NBS Schumann, and practising architects and construction professionals.

1. Follow consistent editorial principles

Specifications should use plain, unambiguous language to avoid misinterpretation. Unnecessary or unclear wording can lead to confusion, disputes and issues with project execution.

Best practice: use the ‘seven Cs’ for direct and simple language: 

• Clear – using plain, unambiguous language.
• Concise – avoid any unnecessary wording.
• Correct – reference the correct, current standards.
• Complete – include the right level of information.
• Comprehensive – use templates to ensure that the required decisions are made.
• Consistent – use consistent structure, terminology and style.
• Coordinated – coordinate your specification with all other documentation, such as drawings and schedules.

Common mistake: using ambiguous wording that lacks the necessary instructions. For example, instead of writing 'The contractor shall provide some spare tiles', clarify the requirements, e.g. 'Provide 20 spare tiles of each type used, including all variations in colour and finish'.

2. Use a structured classification system

Content in a specification can be structured in different ways. Consistent use of an established classification system, such as Uniclass or CAWS, is essential to creating a clear structure for the specification and for managing project information more generally. 

Best practice: choose Uniclass or CAWS for standardised classification, and ensure that all project parties work to the same classification system.

Common mistake: mixing classification systems within what should be a coordinated set of project information.

3. Align specifications with design responsibilities

Specifications should clearly reflect the design responsibilities, detailing who is responsible for which elements of the project. This information must be aligned with the responsibilities recorded in other documentation, such as the design responsibility matrix and/ or appointment contracts. 

Best practice:

• Use the terms 'Descriptive (D)' and 'Prescriptive (P)' to indicate the level of specification information provided.
• Specify which aspects of the design require further specialist input.

Common mistake: assuming and specifying in a way that does not reflect the level of design responsibility.

4. Coordinate your information

As set out in the ‘seven Cs’, your specification should be coordinated with project drawings, schedules, models and other documentation. Discrepancies in project information can lead to errors and disputes.

Best practice:

• Ensure that specification reference codes match the information in drawings and models.
• Use digital tools, such as NBS Chorus and other BIM software, to help coordinate information.
• Regularly review and update specifications to reflect design changes.

Common mistake: failing to update specifications when drawings or models are revised, and vice versa.

5. Manage changes and publishing

Specifications must be kept up-to-date and properly documented to track revisions and ensure compliance. A clear change management process helps avoid miscommunication, and is essential to maintaining the ‘golden thread’ of information for buildings from concept to handover.

Best practice:

• Maintain a clear record of the specification’s publication history.
• Track and record changes to the content of your specifications.

Common mistake: not tracking and communicating changes properly, leading to outdated or conflicting specification documents being used on site.

Further guidance

Following these top tips is a great first step towards getting your specifications right. To provide further guidance on editorial style, classification systems, publishing and more, NBS has created the ‘Best Practice Guide to Specification Writing’. 

The guide is a free, customisable resource to help architects, engineers and construction professionals develop a robust, standardised approach to specifications.

Download the guide now