14 October 2020

As you read through the article and watch the webinar, it’s important to note that this information is not just relevant to conservation projects; refurbishment, repair, renewal and maintenance projects are equally applicable. In addition, many of the systems and product clauses in NBS Chorus authored for new works are also appropriate for use and can be emended to suit where necessary.

What is conservation?

According to Historic England, conservation is the process of maintaining and managing change to a heritage asset in a way that sustains and, where appropriate, enhances its significance. While some heritage assets are preserved completely in their original physical form, most can be adapted for continued use in a way that preserves their meaning.

How is conservation different from other building work?

Conservation in construction doesn’t conform to normal construction parameters; therefore, specifying a conservation project must consider many unique elements. For instance, how do we:

  • Ensure that as many of the original materials and architectural elements as possible are retained in their original condition?
  • Effectively plan and organize specific conservation works, without extensive and, often invasive, detailed investigation of the existing structure.
  • Add to the asset so that it meets modern-day codes and needs without jeopardising its historical significance?
  • Ensure that any additions or repairs do not alter the original material and that those additions or repairs can be removed without affecting the original material either now or in the future?
  • Improve the value of the building while still preserving its history?
  • Develop a maintenance plan to ensure that the renewed building does not suffer from further decay?

Specification is incredibly important in conservation projects, not just in terms of workmanship quality but in sampling, testing, planning and serving as guidance for continued preservation and maintenance.

The RIBA Plan of Work 2020

Since its extensive update in 2013, the RIBA has been collecting feedback from the construction industry and its clients on how to further improve things. The 2020 plan of work incorporates much of that, providing more comprehensive sections and an expanded glossary. A key part of the update includes a stronger focus on sustainability, as well as an introduction to project strategies, BIM integration and new procurement guidance. Other changes have been made around planning and at what point plans should be submitted (end of stage three), and the title of stage three has changed to better reflect its purpose. The new Plan of Work also pays respect to the Hackitt Report’s golden thread of information and recommends that asset and facilities management teams are brought in at stages six and seven.

Specifying through the Plan of Work stages

Every element in the Plan of Work 2020 and the specification process integrates vital information. This needs to be detailed and accessible at every stage, with a clear and transparent line of data from beginning to end to ensure continued compliance and a high level of accountability.

Before you begin – key questions to ask

There are a variety of vital questions we need to ask at the beginning of the specification process. These include:

  • What is this heritage site, why does it matter, and who cares about it?
  • Where is it located? What kind of condition is it in? What are we exposing ourselves to?
  • What are the current threats to the asset?
  • What improvements can be made? How do we adapt to the site and implement measures that allow for a change of use?
  • How will people engage with the asset? How can we improve public access? How do we heighten the public’s awareness and understanding?
  • How do we ensure it meets modern regulations? How do we adapt it to climate change?
  • What factors will influence how the asset is cared for and managed?

During these early stages, we also need to define any specific risks that are associated with our conservation project – e.g., asbestos, lead, etc. – and determine if or how any nearby activities might affect the work.

Flexibility is key – mixing performance and prescriptive clauses

Heritage projects tend to break standard specifying rules, so it’s especially important to be flexible. It is fitting for conservation specifications to be a mixture of performance and prescriptive clauses. For example, thatch roofing requires extremely specific materials and application knowledge and lends itself to a high degree of prescription of the thatcher’s craft. However, within the same specification you may also need performance clauses to cover internal fire protection – on the underside of the thatch or for ventilation to eaves – to reduce the risk of condensation. When using NBS Chorus to specify, its inbuilt flexibility makes it easy to mix prescriptive and performance clauses, so, there is no reason why you can’t put them together.

Defining survey parameters, sampling and testing

It is also vital in conservation projects to be specific about survey parameters – scope, purpose and limitations. For example, is the building currently in use and, if so, how do we work around that? Sampling and testing are also key. Any time you undertake work on a pre-existing building – particularly one with historic elements – you’re relying on unknowns. So, you need to find out what’s there. With older assets like these, that requires specialists to help you determine the materials and methods that you’ll need to use. Because of this, specialist surveyors experienced in specific building construction techniques and materials may need to be procured to undertake detailed inspections.

Relying on specialised, third-party information

There are very few architects and specialists who can deal with the level of detail required for conservation projects without support; therefore, there is a strong element of trust that must be placed on third-party individuals. This needs to be included in the specification, creating a golden thread of information from start to finish, detailing responsibilities, decisions made, and actions taken. In essence, you’re trying to retain something – give it another life – and, therefore, the quality of communication and information must be of the highest standard possible. It’s also important to remember that these contract-specific documents may subsequently become part of the historical record for future works.

Developing a unique supply chain

Depending upon the type of conservation project you’re undertaking, a continued supply chain may need to be established to ensure the asset remains in good condition. For example, in large structures like York Cathedral and the Oxford University estates, there is an ongoing need for specialist designers and contractors to ensure the structures are properly cared for. While rarer than it used to be, there are some organisations and assets that still retain in-house carpenters, tradesmen and stone masons for that purpose. Either way, these relationships are ongoing, lasting long past handover. Therefore, communication and collaboration are key, and having a good specification as the foundation for a living asset document is vital.

Balancing demand between modern design and conservation work

When it comes to demands on design vs conservation, it’s important to establish the right balance between functionality – i.e., ensuring effective use – and retaining the asset’s originality. Building design and user’s requirements have changed over time, and it can be a challenge to meet today’s standards in a way that doesn’t diminish the asset’s historic value while still allowing the building to be useful. Of particular concern is meeting current building regulations. It can be challenging to incorporate modern requirements (e.g., thermal insulation levels) with historical building techniques and finishes. Therefore, it requires a close liaison between designer, contractor and local building control. There can and probably will be tensions, but it is crucial to find ways to accommodate necessary change. A good specification provides that balance, adapting and changing, as necessary.

Handover and management

The RIBA Plan of Work 2020 recommends bringing in facilities and asset management at the end of stage 6 for a light touch evaluation and having them fully involved throughout stage 7. In a conservation project, bringing these groups into the project at this stage helps ensure that everyone is on the same page and that the right resources for continued conservation and maintenance are in place.

It’s also important to note that many of the works performed in heritage-based conservation projects are cyclic in nature. Therefore, specification can be greatly enhanced by involving any previous asset management teams throughout (and early in) the process. Their feedback on the success (or otherwise) of design and application solutions can assist in ongoing design and product selection.

Conservation and specifying with NBS Chorus

Most heritage work is construction led, and every decision has an impact on project success. Simple choices can have an overarching effect on what happens next. This means that the execution needs to be clearly defined, especially considering that conservation projects break so many of the rules that apply in other project types. NBS Chorus has an inbuilt flexibility that ensures that it works as easily with conservation projects as it does with new builds. Clauses are adaptable, and existing content can be readily amended. As noted earlier, it isn’t unusual for conservation projects to rely on a mixture of performance and prescriptive clauses, and NBS Chorus allows for that.

For a comprehensive view of how Chorus clauses can be adapted to suit conservation and other projects, please watch the associated webinar at thenbs.com/events.


NBS Chorus

NBS Chorus is a flexible cloud-based specification platform that allows you to access your specifications across locations and organisations. It is suited to both performance and prescriptive specifying and has editable clauses that are supported by technical guidance. Our content is continuously evolving, informed by research, user feedback and industry drivers, and we are continually reviewing it to improve clarity and usefulness.

NBS Source

NBS has created a new manufacturer product platform we call NBS Source. Bringing together NBS BIM Library, NBS Plus and the RIBA Product Selector, NBS Source provides a single source for product information that seamlessly integrates into a project’s workflow and provides an additional level of enhanced product data in a consistent, structured format. For more information about NBS Source, visit thenbs.com/nbs-source.

The RIBA Plan of Work 2020 Webinar series

Conservation and the RIBA Plan of Work is part of an NBS webinar series addressing various elements of the new Plan of Work 2020, including fire safety, sustainability, conservation and intelligent design. To see it or other parts in the series, please visit thenbs.com/events.