Independent project advisory

The 2026 dutyholder rules in Wales, explained for homeowners

Since 1 July 2026, even an ordinary home extension in Wales needs named people responsible for building regulations compliance. Here's what that means and how to get it right.

What changed

Wales introduced a dutyholder regime into its Building Regulations from 1 July 2026, modelled on the roles used in construction health and safety. It applies to householders as well as developers. Local authority guidance is clear that every project, however small, needs a client, an appointed Principal Contractor and an appointed Principal Designer, with the appointments in writing.

Dutyholder roles for a domestic building project in Wales from 1 July 2026 You, the client Legal duties since 1 July 2026 Independent adviser Explains, checks competence, prepares the paperwork Appoints in writing Principal Designer Usually your architect or designer Principal Contractor Usually your main builder Building control Notified of the appointments
Who does what under the Welsh rules from 1 July 2026.
House under renovation with scaffold, roof stripped back and openings formed
The rules now apply to ordinary householder work, not just large schemes

Your options as a householder

  • Appoint competent people. Usually your designer takes the Principal Designer role and your main builder takes the Principal Contractor role, recorded in writing.
  • Take a role yourself. You can, but only if you're satisfied you're competent, and you must sign a statement to that effect for building control.
  • Do nothing. Welsh Government guidance says the designer in control of the design becomes the Principal Designer, and the contractor in control of the build becomes the Principal Contractor, by default. That leaves room for confusion about who is actually responsible.

How I help

  • Explain the roles and your duties as the client, in plain English.
  • Check that the people you appoint are competent for the work.
  • Prepare the written appointments and the notifications building control needs.
  • Keep the record straight through to completion and the final declarations.

To be clear about my role: I advise and coordinate. I don't act as your Principal Designer or Principal Contractor. Those roles belong with your designer and your builder, and keeping them separate is part of keeping my advice independent.

Building in Chester or on the Wirral?

England has its own version of these rules under its Building Regulations. If you're near the border and unsure which applies, the answer depends on where the property sits, and I can talk you through it.

Questions

Does this apply to a small single-storey extension?

Yes. The Welsh guidance applies to controlled building work generally, not just large projects. Check with your local building control team if you're unsure whether your work is covered.

Can my builder just do everything?

Your builder can be the Principal Contractor. The Principal Designer role normally sits with whoever controls the design. What matters is that the appointments are made deliberately, in writing, to competent people.

Where can I read the official guidance?

Welsh Government publishes guidance for domestic clients, and your local authority building control team can advise. I'll point you to the right pages as part of any engagement.

Not sure what help you need?

Tell me about your project and I'll tell you honestly whether you need me.

Book a free 20-minute call07714 198743