Building regulations have teeth, mostly polite ones, occasionally sharp, and the homeowners who meet them usually do so by inheritance: the survey that finds the undocumented loft conversion, the sale that stalls on a missing completion certificate. Understanding the actual enforcement machinery turns a frightening letter into a manageable process.

The two main levers

Prosecution. Carrying out building work in breach of the regulations is an offence, committed by the person who did the work (builder) and potentially those who commissioned it.1 Since the Building Safety Act it can also be tried in the Crown Court, where the penalty is an unlimited fine, up to two years’ imprisonment, or both.1 The Act also removed the old two-year time limit on bringing a prosecution.2 Prosecution targets the doer; buying a house with dodgy work doesn’t make you prosecutable for it.

Section 36 notices. The property-facing power: the council requires the owner to alter or remove work that contravenes the regulations.3 This one does attach to you as current owner, whoever did the work. Non-compliance lets the council do the works and recover costs.3 The service window, traditionally 12 months from completion of the work, is now 10 years (in England since October 2023, in Wales since July 2026), so “it’s been a few years, they can’t touch it now” is a weaker comfort than it was.3

Dangerous structures run on separate, faster powers: where a building is dangerous, councils can seek an order requiring the owner to make it safe, or, where immediate action is needed, do the work themselves and recover the cost.4 That is the emergency lane, not the routine one.

The routine reality

Councils enforce with proportion: their goal is compliant buildings, not maximum prosecutions, and most cases resolve through the compliance routes below without a notice ever being served. The letter that opens “it has come to our attention…” is an invitation to engage, the expensive mistakes are ignoring it, or covering up work mid-project after a stop request. Engage early, and building control officers are generally constructive to deal with; our building regulations guide covers the approval process itself.

Inherited unauthorised work: your options

Found (or been found with) work that never went through building control?

  1. Regularisation, retrospective approval: the council inspects (some opening-up is normal), requires any upgrading needed, and issues a regularisation certificate. The clean fix, available for unauthorised work carried out on or after 11 November 1985; costs the application fee plus whatever compliance work is found.5 Right answer when you plan to stay, remortgage or sell without a cloud.
  2. Indemnity insurance, the conveyancing patch: a one-off premium insuring against the financial consequences of enforcement, not against the wall actually falling down. Standard in sales; understand what it does and doesn’t do before relying on it.
  3. Remedy or remove, where the work is genuinely poor, fixing it properly (with building control involved) is both the safe answer and the one that restores full value; a surveyor’s assessment tells you which category you’re in.

Live notice on the table? Take it seriously and take advice. An appeal against a section 36 notice must normally be brought within 28 days of the notice, for example on the ground that the work actually complies.6 In England the appeal goes to the First-tier Tribunal, and in Wales to the magistrates’ court.7 Agreeing a timetable for the remedial work with the council is often possible too.

If you’re the one who commissioned the work

The builder who assured you “we don’t need building control for this” on notifiable work has exposed you to exactly this machinery, and breached the competence and care you were owed.8 Enforcement costs, regularisation fees and remedial works are all claimable losses through the normal dispute routes; the red-flags guide exists so the assurance gets challenged before the plasterboard goes on, not after.

This guide is general information for homeowners in England and Wales, not legal advice.

References (8)

Figures in this note were checked against the sources below on 30 September 2026. Superscript numbers in the text point to them. Every source the site cites, by topic.

  1. 1technicalvery strongThe National Archives (legislation.gov.uk), legislation.RN-0GJHBJSection 35 of the Building Act 1984, as amended by the Building Safety Act 2022, makes contravening building regulations a criminal offence and sharply increased the punishment. A person who contravenes a provision of building regulations, or a requirement imposed by virtue of such a provision, commits an offence. Under subsection (4) a person guilty of the offence is liable on summary conviction to imprisonment for a term not exceeding the maximum summary term for either-way offences, or to a fine, or both; and on conviction on indictment to imprisonment for up to two years, or a fine, or both. After conviction, continued default attracts a further fine on summary conviction not exceeding level 1 on the standard scale for each day the default continues. Building regulations may exempt prescribed provisions from creating an offence or provide defences. Note the separate two-year enforcement time limit in section 35A and the section 36 power to require removal or alteration of offending work.
  2. 2technicalvery strongThe National Archives, guidance.RN-I1BFXOThe former time limit (two years from the offence) for prosecuting a building regulations breach in the magistrates' court. The page records its removal by the Building Safety Act 2022 from 1 October 2023 in England.
  3. 3technicalvery strongThe National Archives (legislation.gov.uk), legislation.RN-NKK4KZSection 36(1) lets the building control authority, without prejudice to prosecuting for a fine, serve notice on the owner requiring work that contravenes building regulations to be pulled down or removed, or at the owner's election altered so as to comply. Section 36(2) applies the same power where work was executed without an application for building control approval, despite refusal of one, or otherwise than in accordance with the requirements of a granted application. Section 36(3) gives the owner 28 days, or longer if the appropriate court or tribunal allows, before the authority may carry out the work itself and recover the reasonable expenses. Section 36(4) is the key protection: a section 36 notice may not be given after 10 years from the date the work was completed. Sections 36(5) and 36(5A) bar a section 36 notice where a building control approval application for work that is not higher-risk building work was granted and the work was executed in accordance with the approved plans and any requirement imposed.
  4. 4technicalvery strongThe National Archives, guidance.RN-I1BNGZSection 78 of the Building Act 1984, the emergency power for a council to act on a dangerous building and recover its costs (section 77 covers orders on the owner).
  5. 5technicalvery strongThe National Archives, legislation.RN-4MV2ZGRegulation 18 of the Building Regulations 2010, unauthorised building work. Where work was carried out on or after 11 November 1985 without approval, the owner may apply in writing for a regularisation certificate. This is the route out of discovering at sale that an extension or loft conversion was never signed off, and the date in it is why anything older is outside the process.
  6. 6technicalvery strongThe National Archives, guidance.RN-YC44EFSection 40 of the Building Act 1984, the right of appeal against a section 36 notice and its 28-day time limit (70 days where an expert report is obtained).
  7. 7technicalvery strongThe National Archives, guidance.RN-6OR2CNSection 126 of the Building Act 1984, defining the appropriate court or tribunal as the First-tier Tribunal in England and a magistrates' court in Wales.
  8. 8technicalvery strongThe National Archives (legislation.gov.uk), legislation.RN-F06Z1FSection 49(1), in Part 1 Chapter 4 of the Consumer Rights Act 2015, states that every contract to supply a service is to be treated as including a term that the trader must perform the service with reasonable care and skill. Section 49(2) directs the reader to section 54 for the consumer's rights when that implied term is breached. This is the single provision that makes poor workmanship by a builder a breach of contract without the homeowner having to prove anything was written down, and it cannot be excluded to the extent it would stop the section 54 to 56 remedies applying.

  1. Building Act 1984, section 35, The National Archives, accessed 30 September 2026. legislation.gov.uk

  2. Building Act 1984, section 35A, The National Archives, accessed 30 September 2026. legislation.gov.uk

  3. Building Act 1984, section 36, The National Archives, accessed 30 September 2026. legislation.gov.uk

  4. Building Act 1984, section 78, The National Archives, accessed 30 September 2026. legislation.gov.uk

  5. The Building Regulations 2010, regulation 18, The National Archives, accessed 30 September 2026. legislation.gov.uk

  6. Building Act 1984, section 40, The National Archives, accessed 30 September 2026. legislation.gov.uk

  7. Building Act 1984, section 126, The National Archives, accessed 30 September 2026. legislation.gov.uk

  8. Consumer Rights Act 2015, section 49, The National Archives, accessed 30 September 2026. legislation.gov.uk