08 June 2021

As seen in this specification example, specification plays a crucial role in every successful project, providing a clear representation of the built asset and creating a continuous, thorough, transparent thread of information to be used by owners, facilities managers, maintenance teams, and beyond to optimise use, reuse, and asset-end activities. 

What is specification?

At its core, specification ensures the efficient and transparent exchange of information between client, designer and contractor. Through specification, you’re using words to describe things that can’t be visualised or explained via a drawing or model.

  • Scope of work
  • Contract type
  • Site conditions
  • Asset performance requirements
  • Applicable standards
  • Installation process
  • Systems and products to be used
  • Quality of work

Types of specification

We use three types of specification in construction.

  • Prescriptive
  • Performance
  • Proprietary


Prescriptive specifications provide details regarding what types of materials are used and how they are installed. This includes:

  • General information like applied quality standards, design requirements, quality control elements and how products are handled.
  • Product-specific details covering what products are to be used for each task and their required performance levels.
  • Execution requirements that address how materials are prepared and installed, including quality testing procedures.


Performance specifications cover a project’s operational requirements and how a product should behave once installed. Performance specs generally entail a lot of testing to ensure the project is within stipulated operational parameters.


Proprietary specifications are used when a specifier wants to include a specific product range or type. Examples of projects that might require proprietary specifications include conservation and renovation projects with a need to match or integrate with existing materials and equipment.

What does specification bring to a project?

By developing a good specification, you remove any confusion around a project’s requirements. Having clear information upfront means that the process will be both more efficient and effective. That, in turn, translates to time, effort and cost savings.

Why specification so essential to your project

In 15 reasons why specifications are still important, NBS Technical Information Director Tina Pringle discusses digitisation in construction and the critical role specification has in a successful project process. Briefly, you should use specification if you want to:

  • Create a clear project definition
  • Provide straight-forward instructions as to what the result should look like
  • Support your drawings
  • Enable more accurate pricing
  • Minimise risk
  • Improve compliance and avoid legal problems
  • Have something legally binding
  • Save time and money
  • Assure the client that you’re delivering what they asked for
  • Deliver an essential resource for asset management and maintenance

How do specification and collaboration go hand-in-hand?

In early 2021, NBS hosted a Collaborative Specification Writing webinar that looked at how specifiers and manufacturers can improve an asset’s safety, sustainability and efficiency through collaboration. Key lessons learnt were then put into an article entitled Three reasons to collaborate on a specification. Highlights include:

  • The need to fall in line with Hackitt Report mandates and recommendations, which emphasise the crucial role specification plays in creating a vital golden thread of information*.
  • The need for specifiers to quickly obtain clear technical information on the products and systems they are reviewing for inclusion in their projects.
  • The benefits gained by using cloud-based specification to support real-time collaboration between the complete project team – from designers and contractors to clients, product manufacturers and end-users.

*The golden thread of information is a shorthand term used to describe digitally held building data that is accurate, up-to-date and accessible to everyone concerned. While not yet standard practice, this is the future of construction, capturing the digital fingerprints of the people involved, recording decisions made and creating transparency through a clear accountability trail.

The time to start writing is now

Specification is an essential part of every successful project, and writing should being as early in the project timeline as possible. Amongst other things, early-stage specification is beneficial for: 

  • Clarifying what clients want to achieve on their project
  • Understanding project performance requirements
  • Discussing complexes, entities, space, locations, elements, systems and products
  • Providing essential information to incorporate into the Employer’s Information Requirements (EIR)

A project specification is a living document. Creating it early on allows the specification to evolve and develop through the project timeline, thus providing vital information from project start through handover and asset management.


This article is based on an original article written in 2020 by the same author for The Construction Information Service. CIS is a comprehensive online collection of industry-relevant publications from around 500 publishers. NBS users with a CIS subscription can take advantage of embedded links across specifications platforms to access research and reference documents. The content is fully searchable, intelligently classified and continuously updated. 

Intelligent cloud-based specification for a digitising construction industry

NBS Chorus is a flexible cloud-based specification platform that allows you to access your specifications across locations and organisations. It is suited to all specifying types, with editable clauses that are supported by technical guidance. Our content is continuously reviewed to improve clarity and usefulness, informed by research, user feedback and industry drivers.

Connecting manufacturers with specifiers

NBS Source provides a single source of product information that seamlessly integrates into a project’s workflow and provides an additional level of enhanced product data in a consistent, structured format. Through Source, manufacturers can put their products in front of specifiers at the exact time they are making product decisions.