An extension or a loft brings in more people than the builder. Most of the letters after their names are memberships, not licences. Here’s what each one does and how to check them.
Architect
- What they do
- Designs it and draws it; can run the job
- Look for
- On the ARB register. RIBA is a membership
- Check on
- ARB register
Architectural technologist
- What they do
- Drawings for planning and building regs
- Look for
- MCIAT (chartered)
- Check on
- CIAT
Structural engineer
- What they do
- Sizes the steels, beams and foundations
- Look for
- A chartered member of IStructE
- Check on
- IStructE
Surveyor
- What they do
- Costs the job, checks the building, party wall awards
- Look for
- MRICS or FRICS; an RICS-regulated firm
- Check on
- RICS
Planning consultant
- What they do
- Planning applications and appeals
- Look for
- MRTPI (chartered town planner)
- Check on
- RTPI directory
Building control
- What they do
- Checks the work and signs it off
- Look for
- The council, or a registered approver
- Check on
- GOV.UK register
Builder
- What they do
- Builds it and runs the site
- Look for
- TrustMark, FMB or a CIOB chartered company
- Check on
- Each one’s search
| Who | What they do | Look for | Check on |
|---|---|---|---|
| Architect | Designs it and draws it; can run the job | On the ARB register. RIBA is a membership | ARB register |
| Architectural technologist | Drawings for planning and building regs | MCIAT (chartered) | CIAT |
| Structural engineer | Sizes the steels, beams and foundations | A chartered member of IStructE | IStructE |
| Surveyor | Costs the job, checks the building, party wall awards | MRICS or FRICS; an RICS-regulated firm | RICS |
| Planning consultant | Planning applications and appeals | MRTPI (chartered town planner) | RTPI directory |
| Building control | Checks the work and signs it off | The council, or a registered approver | GOV.UK register |
| Builder | Builds it and runs the site | TrustMark, FMB or a CIOB chartered company | Each one’s search |
What the law requires
- Only someone on the ARB register can call themselves an architect.
- A private building control company must be registered with the Building Safety Regulator.
- A party wall surveyor needs no particular title, but you can’t be your own.
- As a homeowner, your legal duties for health and safety on site pass to your builder; with more than one firm, to the main contractor, or to your architect if they agree in writing.
- Everything else (RIBA, RICS, MCIAT, CIOB, FMB, TrustMark) is a choice: a sign of standards, not a licence.
New floors and steels usually need an engineer to work out their sizes, and building control will want to see it.
What would your job cost?
Describe it, and see a typical price for your area. Then ask builders who do this work.
Read next
How we wrote this
Written by Structa. The rules come from the official pages below. General information, not legal advice.
- ARB: Information for the public (the Register of Architects) (checked 7 October 2026)
- RIBA: Find an architect (checked 7 October 2026)
- CIAT: Chartered Architectural Technologists (checked 7 October 2026)
- IStructE: Find a structural engineer (checked 7 October 2026)
- Planning Portal: Loft conversion, existing walls and foundations (checked 7 October 2026)
- RICS: Find a surveyor (RICS-regulated firms) (checked 7 October 2026)
- GOV.UK: Party walls, if you can’t agree (checked 7 October 2026)
- RTPI: Directory of planning consultants (checked 7 October 2026)
- GOV.UK: Find a registered building control approver (England) (checked 7 October 2026)
- HSE: CDM 2015 and domestic clients (checked 6 October 2026)
- TrustMark: for homeowners (checked 6 October 2026)
- FMB: Find a builder (checked 7 October 2026)
- CIOB: Directory of Chartered Companies (checked 7 October 2026)