The Building Safety Act 2022 introduced the concept of the "golden thread" — a live, digital record of building information that must be kept accurate and accessible throughout a building's lifecycle. For contractors working on higher-risk buildings, this has changed the rules around what record drawings must contain, how they must be stored, and who is responsible for maintaining them.
The golden thread applies to all higher-risk buildings: residential buildings of at least 18 metres in height or at least seven storeys. It requires that information about the design, construction, maintenance and eventual refurbishment of these buildings is recorded, updated and made available in a clear, accessible format to support ongoing safety management.
This article explains what the golden thread means for contractors producing as-built drawings, what information must be included, and how the obligation to maintain accurate records extends well beyond practical completion.
What Is the Golden Thread?
The golden thread is not a single document or drawing set. It is a structured collection of information that demonstrates how a building has been designed and constructed to be safe, and what is needed to keep it that way.
It includes design intent, risk assessments, material specifications, installation records, inspection reports and record drawings. All of this must be digital, and it must be kept up to date as changes are made to the building over time.
The golden thread has two components: the golden thread of information, which covers all building safety information, and the golden thread of building information, which focuses specifically on the physical characteristics of the building as constructed. Record drawings sit squarely within this second category.
How the Golden Thread Affects Record Drawings
For contractors, the biggest change is that as-built and record drawings must now form part of a structured information set that will be accessed and updated over the building's life. They are no longer simply a handover deliverable that gets filed away.
This means record drawings must be:
- Digital and editable, not just PDF scans
- Accurate to what was actually installed, incorporating all variations and changes
- Clearly structured and labelled so non-technical users can navigate them
- Stored in a way that supports ongoing access and updates
- Linked to other golden thread information such as product datasheets, warranties and risk assessments
In practice, this requires a higher standard of discipline during the construction phase. It is no longer acceptable to leave record drawing production to the final weeks of a project, or to hand over sets that reflect design intent rather than what was actually built.
What Must Be Included in Record Drawings for the Golden Thread
The Building Safety Regulator has published guidance on the type of information expected within the golden thread. For M&E contractors and building services engineers, record drawings must capture:
- The location and layout of all building services installations, including mechanical, electrical, plumbing, fire suppression and ventilation systems
- Riser diagrams showing vertical distribution of services
- Plant room layouts and equipment schedules
- Distribution board schedules and final circuit details
- Fire alarm zones and detector locations
- Emergency lighting circuits and luminaire positions
- Fire stopping and compartmentation details, especially where services penetrate fire-rated walls or floors
- Details of all products used, including make, model and relevant certification
This level of detail goes beyond what has traditionally been provided in many handover packages. Contractors working on higher-risk buildings should plan for a more rigorous redline markup incorporation process to ensure final drawings reflect reality.
Who Is Responsible for Maintaining the Golden Thread?
During the design and construction phase, the principal contractor is responsible for creating and maintaining the golden thread. This includes ensuring that all subcontractors provide accurate, timely information about what has been installed.
At handover, the golden thread is passed to the building's Accountable Person — usually the building owner or landlord. From this point, the Accountable Person is legally responsible for keeping the information current and accessible.
This creates a clear obligation for contractors to deliver complete, usable information at handover. Gaps or inaccuracies in the record drawings can expose both the contractor and the Accountable Person to regulatory action.
Digital Formats and Storage Requirements
The Building Safety Regulator expects golden thread information to be stored digitally in formats that allow it to be accessed, updated and shared easily. For record drawings, this typically means native CAD formats such as DWG or Revit, not locked PDFs.
Many clients are now specifying that record drawings must be delivered in accordance with ISO 19650 and stored in a Common Data Environment (CDE) that the Accountable Person can continue to use post-handover. This allows future contractors carrying out refurbishment or maintenance work to access and update the drawings as needed.
Some larger clients are also requesting that record drawings be linked to asset registers and CAFM systems, with live hyperlinks between drawings and product datasheets, warranties and maintenance schedules.
Fire Safety Information and Record Drawings
One of the most critical elements of the golden thread is the Fire and Emergency File, which must be provided to the Accountable Person at handover. This file must include drawings showing:
- Fire stopping and compartmentation
- Fire alarm detection and call points
- Emergency lighting and escape routes
- Sprinkler and suppression system layouts
- Smoke control and ventilation systems
- Firefighting equipment and dry risers
These drawings must be clearly annotated and easy to interpret, as they will be used by building managers, fire risk assessors and emergency responders. Ambiguity or missing information can have serious safety implications.
Implications for Subcontractors and Fit-Out Contractors
M&E subcontractors working under a main contractor on a higher-risk building must provide record drawing information to the principal contractor in a format and at a level of detail that supports the golden thread obligation. This is often set out in the contract, but even where it is not explicit, the duty flows from the Building Safety Act itself.
Fit-out contractors working in existing higher-risk buildings must also consider whether their work affects the golden thread. Any change to building services, compartmentation or fire safety systems should be recorded and the golden thread updated accordingly.
Outsourcing Record Drawing Production
Given the increased complexity and compliance burden, many contractors are choosing to outsource record drawing production to ensure accuracy and consistency. Outsource CAD works with M&E and building services contractors to produce compliant record drawings from site redlines, photographs and marked-up PDFs, delivered in native CAD or Revit formats ready for inclusion in the golden thread.
Outsourcing allows site teams to focus on delivery while ensuring that handover documentation meets both client expectations and regulatory requirements.
Enforcement and Penalties
The Building Safety Regulator has powers to inspect the golden thread and take enforcement action where it is incomplete, inaccurate or not being maintained. Penalties can include compliance notices, stop notices and in serious cases, prosecution.
For contractors, the reputational and commercial risk of handing over inadequate information is significant. Clients are increasingly writing golden thread compliance into contracts, with retention and payment linked to the quality and completeness of handover information.
Practical Steps for Contractors
To meet golden thread requirements, contractors should:
- Plan for record drawing production from the start of the project, not as an afterthought
- Establish clear processes for collecting and incorporating site changes and redlines
- Ensure all subcontractors understand their obligations to provide accurate record information
- Use digital tools and workflows that support version control and traceability
- Deliver record drawings in editable, structured formats that can be updated by others
- Include links or references to related documents such as O&M manuals, product datasheets and risk assessments
Where internal resources are stretched, working with a specialist provider who understands both CAD production and Building Safety Act requirements can reduce risk and improve handover quality.
If you're working on a higher-risk building and need support with compliant record drawing production, get in touch with our team at info@outsourcecad.com or call +44 28 9009 8876.
