Building Act 1984

Reviewed by Bradley Askew, Solicitor (non-practising), England & Wales. Reviewed 15 July 2026.

The Building Act 1984 is the principal statute governing building control in England and Wales. It gives the Building Regulations their legal force and sets out how building work is checked, approved, and enforced. If you are a landlord planning an extension, loft conversion, HMO conversion, or structural alteration, this Act determines whether you need building regulations approval, which route you use to get it, and what happens if you build without it. Since the Building Safety Act 2022 amended the enforcement provisions, unauthorised building work carries an unlimited fine and up to two years' imprisonment, and the local authority can act against it for up to ten years after completion — a substantial tightening from the position under the original 1984 Act.

Key takeaways

• The Building Act 1984 itself contains little technical detail. It empowers the Secretary of State (and Welsh Ministers, for Wales) to make Building Regulations, and creates the approval and enforcement framework. The technical standards live in the Building Regulations 2010 and the Approved Documents.
• There are three formal routes to building regulations approval: full plans (local authority), building notice (local authority), and using a Registered Building Control Approver (RBCA) — the private-sector route that replaced "Approved Inspectors" from 6 April 2024. A separate mechanism, competent person self-certification, lets registered installers sign off specified work (electrics, gas appliances, replacement windows) without a building control application at all.
• Carrying out building work without the required approval is a criminal offence under section 35 of the Act. Since the Building Safety Act 2022 amendments (in force from 6 April 2023), the maximum penalty is an unlimited fine and/or up to two years' imprisonment — up from the original £5,000 fine with a £50-a-day continuing penalty.
• The local authority can serve a notice under section 36 requiring non-complying work to be pulled down or altered, and — since the Building Safety Act 2022 — it can do so for up to ten years after completion (previously 12 months).
• "Higher-risk buildings" (broadly, residential buildings at least 18m tall, or with at least 7 storeys, containing 2 or more residential units) sit outside the ordinary building control system. They are regulated by the Building Safety Regulator through a three-Gateway process under the Building Safety Act 2022, not by a local authority or RBCA.
• If work was carried out without approval, a regularisation certificate can retrospectively confirm compliance — but only through the local authority, and only if the work can be shown (sometimes by opening it up) to meet the regulations that applied when it was built.

What the Act does

The Building Act 1984 is the legislative skeleton of the building control system in England and Wales. On its own it says relatively little about how buildings should actually be built. Instead, it:

• gives the Secretary of State (in England) and Welsh Ministers (in Wales) the power to make Building Regulations;
• creates local authority building control departments and gives them enforcement powers;
• allows private-sector building control bodies to operate alongside local authorities;
• sets out the criminal offences and enforcement notices used against non-compliant or unauthorised work.

The substantive technical requirements — fire safety, structural safety, energy efficiency, access, sanitation, ventilation — are set out in the Building Regulations 2010 and the accompanying Approved Documents, covered below. The Act has been amended repeatedly since 1984, most significantly by the Building Safety Act 2022, which followed the Grenfell Tower fire and created an entirely new regulator and approval regime for higher-risk residential buildings.

For most landlords, the Act's relevance is indirect — you are operating an existing building, not constructing one. It becomes directly relevant whenever you carry out work that meets the statutory definition of "building work": extensions, conversions, structural alterations, changes of use, or the installation or replacement of controlled services such as electrics, heating, or drainage.

When building regulations approval is required

Building regulations approval is required whenever "building work" within the statutory definition is undertaken. The main categories:

• Erection or extension of a building — new construction, extensions, conservatories above a defined size, garage conversions, loft conversions.
• Material alteration of a building — structural changes, removal of load-bearing walls, replacement of major systems.
• Provision or extension of a controlled service or fitting — heating systems, plumbing, electrical installations, drainage, ventilation.
• Material change of use — converting a single dwelling into multiple units (an HMO conversion), converting commercial premises to residential, or changing a property to a different residential category.
• Underpinning of foundations.
• Insertion of insulation into cavity walls.

Some minor works are exempt — small porches, purely cosmetic internal work, and repairs that do not affect controlled services. The exemptions are narrowly drawn and have tightened over time, so always check with your local authority or a Registered Building Control Approver before assuming a project is exempt, rather than relying on general guidance.

The routes to approval

The Act allows three formal ways to obtain building regulations approval, plus a separate self-certification mechanism for specified trades.

1. Full plans submission

The most thorough route. Detailed plans, specifications, and (where relevant) structural calculations are submitted to the local authority's building control department before work starts. The authority reviews the submission and approves it, sometimes with conditions, then inspects the work at key stages — foundations, drainage, structure, completion — issuing a completion certificate once all inspections pass.

Full plans is generally preferred for substantial projects, because errors are identified before construction begins rather than discovered mid-build. Timescales and fees vary by local authority and project size — check current charges with your building control body before budgeting.

2. Building notice

A simpler route for smaller, more straightforward projects. You notify the authority that work is intended, without submitting detailed plans in advance. There is no formal pre-construction approval; inspections happen as the work proceeds, and any problems are identified and addressed in real time. It suits small extensions, simple alterations, and single-room loft conversions, but is riskier for anything complex, since a defect found mid-build can mean expensive remedial work.

3. Registered Building Control Approver (RBCA)

A private-sector alternative to the local authority. From 6 April 2024, the previous "Approved Inspector" system was replaced by Registered Building Control Approvers — private companies registered with, and overseen by, the Building Safety Regulator under a statutory code of conduct. An RBCA carries out the same core function as a local authority building control department: reviewing plans, inspecting work, and issuing the completion certificate. RBCAs can supervise work on buildings that are not "higher-risk" (see below); higher-risk building work must go through the Building Safety Regulator directly.

If you have older guidance, contracts, or professional correspondence referring to an "Approved Inspector", that terminology has been superseded — the correct current term is Registered Building Control Approver.

Competent person self-certification

Separate from the three routes above, competent person schemes (also called self-certification schemes) let installers registered with an authorised scheme certify their own work as compliant, for specified categories such as electrical installations (Part P), gas appliances, oil heating, and replacement windows and doors. No building control application is needed for that specific work; the installer notifies the scheme, which notifies the local authority, and issues you a compliance certificate — normally within around eight weeks of completion. Membership of a scheme is the installer's choice, not yours: you can still use a local authority or RBCA route instead if your installer isn't registered with a scheme.

Higher-risk buildings: the Building Safety Act 2022 regime

The Building Safety Act 2022 created a parallel building control system for higher-risk buildings — broadly, residential buildings that are at least 18 metres tall or have at least 7 storeys, and contain at least two residential units (certain buildings such as hospitals and care homes are also captured during design and construction). For these buildings, ordinary building control does not apply:

• The building control authority is the Building Safety Regulator (BSR), not a local authority or RBCA.
• Approval runs through three Gateway checkpoints: Gateway 1 at the planning stage (a fire statement, in force since August 2021), Gateway 2 before construction starts (the BSR approves the detailed plans), and Gateway 3 before the building can be occupied (a completion certificate).
• The building's design, construction and ongoing safety information must be kept as a continuously updated "golden thread" of records.
• Once occupied, a Principal Accountable Person must register the building with the BSR and take ongoing responsibility for managing building safety risks.
• The BSR has substantial enforcement powers, including the ability to halt construction.

Most landlord-owned residential property falls well below the 18m/7-storey threshold and is unaffected by this regime — but it matters for landlords with interests in blocks of flats, larger converted buildings, or mixed-use developments that meet the threshold. See our Building Safety Act 2022 guide for the higher-risk regime in full, including accountable person duties and resident engagement requirements.

Wales note: the Building Act 1984 applies in both England and Wales, but the Building Safety Regulator and Gateway regime were implemented for England; Wales has its own arrangements for higher-risk buildings, developed separately by the Welsh Government. If you have a higher-risk building in Wales, check Welsh Government guidance rather than assuming the English regime applies unchanged.

The Approved Documents

Building Regulations are supported by Approved Documents — official technical guidance on how to satisfy each Regulation. The current Approved Documents are:

• Approved Document A — Structure.
• Approved Document B — Fire safety. The most relevant to landlords; covers fire compartmentation, escape routes, and fire-resistant construction. Significantly tightened since 2018, including the ban on combustible materials in the external walls of relevant buildings over 18m.
• Approved Document C — Site preparation and resistance to contaminants and moisture.
• Approved Document D — Toxic substances.
• Approved Document E — Resistance to sound.
• Approved Document F — Ventilation.
• Approved Document G — Sanitation, hot water safety and water efficiency.
• Approved Document H — Drainage and waste disposal.
• Approved Document J — Combustion appliances and fuel storage systems.
• Approved Document K — Protection from falling, collision and impact.
• Approved Document L — Conservation of fuel and power. Covers insulation, glazing, and energy efficiency.
• Approved Document M — Access to and use of buildings.
• Approved Document O — Overheating. Introduced in 2022 for new residential buildings.
• Approved Document P — Electrical safety.
• Approved Document Q — Security in dwellings.
• Approved Document R — Physical infrastructure for high-speed electronic communications.
• Approved Document S — Infrastructure for charging electric vehicles. In force since June 2022 for most new residential development with parking.

Following an Approved Document is one way to satisfy the corresponding Regulation, but not the only way — alternative approaches that meet the same standard are permitted. In practice, most building control bodies expect Approved Document compliance unless there is a specific, evidenced justification for an alternative.

Enforcement and penalties for unauthorised work

Carrying out building work without the required approval, or in a way that contravenes the Building Regulations, is a criminal offence under section 35 of the Act. The Building Safety Act 2022 substantially strengthened this regime, in force from 6 April 2023:

• Penalty: an unlimited fine and/or up to two years' imprisonment on conviction, replacing the previous cap of £5,000 with a £50-a-day continuing fine.
• Compliance and stop notices: new powers under sections 35B–35D of the Act let the building control authority require someone to stop contravening, or stop work entirely, without waiting for a prosecution.
• Section 36 enforcement notice: the authority can require unauthorised or non-complying work to be pulled down or altered. This can now be served for up to ten years after completion of the work — extended from 12 months by the Building Safety Act 2022.
• Local authority remediation at the owner's expense where an enforcement notice is not complied with, typically at a marked-up cost.

If work was carried out without approval and you now want to resolve it, a regularisation certificate is often available — a retrospective application to the local authority (not an RBCA) covering work from 11 November 1985 onwards. The authority inspects the work, sometimes requiring exposure of hidden elements, and issues a certificate only where the work meets — or is made to meet — the standards that applied when it was built.

Beyond the direct legal exposure, unauthorised work creates practical problems that often matter more to a landlord day to day:

• Mortgage lenders frequently refuse to lend, or attach conditions, where a property has unresolved building regulations issues.
• Property sales are routinely delayed or fall through when buyers' searches reveal unauthorised works.
• Insurance claims for damage connected to unauthorised work may be refused.
• HMO licence applications can fail where the property has unresolved unauthorised works, particularly around fire safety.

Common mistakes landlords make

• Assuming planning permission covers building regulations, or vice versa. They are separate systems with separate applications, separate fees, and separate consequences for non-compliance.
• Treating an HMO conversion as purely a licensing matter. A material change of use can trigger a separate building regulations obligation on top of the HMO licence requirement under the Housing Act 2004.
• Relying on a builder's assurance that "it's all sorted" without seeing the completion certificate. Ask for, and keep, the paperwork — you will need it on sale, remortgage, or insurance claim.
• Assuming a small job is automatically exempt. The exemptions are narrow and specific; check before you start, not after.
• Doing nothing about historic unauthorised work discovered on a property you already own. A regularisation certificate is usually a better path than waiting for it to surface in a sale.

Next step

This page explains the general law of England and Wales — it is legal information, not a substitute for advice on your specific project or property. If you are planning building work, converting a property, or have discovered unauthorised work on a property you own or are buying, speak to your local authority building control team or a Registered Building Control Approver about the approval route, and to a regulated adviser if the situation is disputed, high-value, or time-critical. This site is not a law firm and is not regulated by the Solicitors Regulation Authority; reading this page does not create a solicitor–client relationship.

Authoritative sources

• Building Act 1984.
• Building Act 1984, section 35 — offence of contravening building regulations.
• Building Act 1984, section 36 — removal or alteration of offending work.
• Building Safety Act 2022.
• Building Regulations 2010.
• Approved Documents (GOV.UK).
• Competent person schemes (GOV.UK).
• Criteria for a higher-risk building (GOV.UK).
• Regularisation — retrospective building control approval (Planning Portal).
• Our Building Safety Act 2022 guide — for higher-risk buildings in full.
• Our HMO setup guide — for HMO conversion building regulations.