Building Regulations: Full Plans vs Building Notice vs Regularisation Explained

Building Regulations approval is one of the most important — and most misunderstood — aspects of home improvement projects in England and Wales. Homeowners regularly confuse it with planning permission, assume a competent builder will take care of it automatically, or discover only when they come to sell that vital certificates are missing. This guide explains what Building Regulations approval actually means, the three routes available to you, what inspections are carried out, and why the completion certificate is so important for mortgage lenders and conveyancers.

What Building Regulations Approval Actually Means

Building Regulations are a set of minimum technical standards that ensure buildings are safe, healthy, energy-efficient, and accessible. They cover everything from structural stability (Part A) and fire safety (Part B) to ventilation (Part F), thermal performance (Part L), drainage (Part H), and electrical safety (Part P). Approval means that a Building Control body — either the Local Authority Building Control (LABC) or a Registered Building Control Inspector (RBCI, formerly known as an approved inspector) — has accepted that the work meets those minimum standards.

Building Regulations are entirely separate from planning permission. Planning permission governs what you build, where, and how it looks; Building Regulations govern how safely and to what technical standard it is built. Many projects need both; some need only one; a few require neither. Most extensions, loft conversions, garage conversions, new electrical circuits, structural alterations, replacement boilers, and drainage work all require Building Regulations approval even when they are permitted development and require no planning permission whatsoever. For a clear explanation of how the two systems relate, see our Building Regulations vs Planning Permission guide.

The Three Routes to Building Regulations Compliance

Route 1: Full Plans

The Full Plans route is the most thorough and provides the greatest legal certainty. You (or your architect or designer) submit detailed drawings and specifications to Building Control before work begins. The Local Authority has a five-week target (extendable to two months by agreement) to check the drawings and either approve them, conditionally approve them, or reject them with a written notice identifying the shortcomings.

Once approved, the contractor can commence work knowing the design has been vetted in advance. The Building Control officer then carries out site inspections at key stages (see below). If work is carried out in accordance with the approved plans, a Completion Certificate is issued on satisfactory final inspection.

Best for: extensions, loft conversions, new dwellings, or any project where design certainty, phased work, or resale value justifies the upfront investment in detailed drawings.

Advantages:

• Design errors are identified before expensive construction begins
• Approved plans provide a legal record protecting homeowner and contractor
• Completion certificate is issued as a matter of course
• Suitable for all project types including commercial and fire-safety-sensitive work

Disadvantages:

• Requires fully detailed drawings before work can start
• Lead time of 5–8 weeks from submission to approval

Route 2: Building Notice

The Building Notice route allows work to begin with two clear working days' notice to the Local Authority — no drawings are submitted in advance. The Building Control officer visits the site at key stages, assesses the work as it progresses, and advises on compliance. This route is faster to initiate and suits straightforward projects where the builder is experienced with standard construction and the work is not highly complex.

Critical restrictions: a Building Notice cannot be used for:

• Commercial or industrial premises
• Buildings to which the Fire Safety Order 2005 applies
• Work within 3 metres of a public sewer
• Buildings covered by the Regulatory Reform (Fire Safety) Order 2005

Under the Building Notice route, no formal approval of drawings is issued and, traditionally, no completion certificate is automatically issued. The Local Authority may issue a written acknowledgement but this is not the same as a formal completion certificate. Some LABC bodies now issue completion certificates for Building Notice work, but practice varies — confirm with your local authority at the outset.

Best for: relatively straightforward domestic work (a simple extension or bathroom refit) where the builder is confident of compliance and the homeowner understands that design responsibility lies with the contractor rather than being pre-approved.

Advantages:

• Fast to start — 48 hours' notice only
• Lower upfront design cost (no full drawings required)

Disadvantages:

• No advance confirmation that the design complies — compliance risk sits with the contractor and owner
• Cannot be used for work involving certain fire safety situations, commercial premises, or near public sewers
• Completion certificate position varies by authority — clarify before starting

Route 3: Regularisation

Regularisation is the retrospective route — used when building work has been carried out without Building Regulations consent, or without following the approved plans, and now needs to be formally regularised. This commonly arises when:

• A homeowner carried out work without realising approval was needed
• A previous owner's work was never signed off
• Work was completed but the final inspection was never called
• Solicitors on a property sale identify missing certificates

The process: you submit a Regularisation application (with or without drawings, depending on what evidence is available). The Building Control officer inspects the work and will almost certainly require opening up — removing floor coverings, exposing structural elements, opening stud walls — to verify that concealed work meets the standards. The authority then either accepts the work, requires remediation, or in the worst case refuses to regularise it if the work cannot be demonstrated to comply.

The Regularisation route carries a higher fee (typically around 25% more than the equivalent Full Plans fee), an eight to twelve-week process (often longer in practice), and critically, no guarantee of approval. If the work is found to be non-compliant and remediation is not feasible, the Local Authority can serve an enforcement notice requiring demolition or alteration.

Best for: inherited problems at purchase, historic works without paperwork, or last-resort situations where indemnity insurance is not an acceptable alternative.

Typical Fee Comparison

Fees are set by each Local Authority and vary. The figures above are indicative for England. Many authorities use a works-value-based scale. Registered Building Control Inspectors (RBCIs) may offer competitive fees — obtain quotes from both LABC and an RBCI for larger projects.

Inspection Stages

For Full Plans projects, Building Control will inspect at the following key stages (you must give appropriate notice before covering each):

1. Commencement — notify within two days of starting work
2. Foundation excavation — before concrete is poured
3. Foundation concrete — before backfilling
4. Oversite/damp proof membrane — before concrete slab is poured
5. Damp proof course — before covering
6. Structural frame / wall plate — for timber frame, inspect before boarding
7. Roof structure — before tiling
8. Drainage — before backfilling trenches
9. Insulation — before covering
10. Final completion — all works complete, ready for occupation

The Completion Certificate: Why It Matters

A Completion Certificate is the formal written confirmation that all inspected work has been found to comply with the applicable Building Regulations. It is issued by the Local Authority (or RBCI) following a satisfactory final inspection.

The completion certificate matters because:

• Conveyancers routinely request it when you sell or remortgage. Missing certificates are one of the most common causes of delays and complications in property transactions.
• Mortgage lenders will not lend on properties where significant work lacks a completion certificate unless indemnity insurance is obtained — and not all lenders accept indemnity insurance as a substitute.
• Home insurance policies may be affected if work was carried out without Building Regs approval — check your policy wording.

If certificates cannot be located, your first step is to check with the Local Authority (they retain records indefinitely). If records have been lost or work was never inspected, you will likely need indemnity insurance to facilitate a sale, which typically costs £150–£500 for a single project.

Local Authority vs Registered Building Control Inspector

Since April 2024, private sector building control professionals have operated as Registered Building Control Inspectors (RBCIs) under the Building Safety Act 2022, regulated by the Building Safety Regulator. Either an LABC or an RBCI can be used for most domestic projects. RBCI services are competitive and often provide a more responsive service; LABC fees are set locally. For Higher Risk Buildings (buildings over 18 metres or 7 storeys), mandatory Gateway processes apply and the Building Safety Regulator is the Building Control Authority.

Consequences of Not Getting Approval

Proceeding without Building Regulations approval, or failing to obtain a completion certificate, carries real risks:

• Enforcement notice: the Local Authority has powers to require alteration or demolition of non-compliant work
• Time limits: for most dwellinghouse work, enforcement action can be taken for up to ten years after completion (two years for building operations, longer for change of use and fire safety)
• Sale complications: missing certificates delay or block conveyancing and may require indemnity insurance
• Safety risks: unchecked structural work, drainage, or electrical installations may present genuine hazards to occupants

Summary Checklist

• ✅ Building Regulations are separate from planning permission — most building work needs both
• ✅ Full Plans: submit drawings in advance, get formal approval, most certainty — best for extensions and loft conversions
• ✅ Building Notice: fast start, no drawings, but cannot be used for commercial, fire-safety-sensitive, or sewer-adjacent work
• ✅ Regularisation: retrospective route for historic work without consent — more expensive, slower, no guarantee of approval
• ✅ Always obtain a Completion Certificate — keep it safe, it will be needed when you sell
• ✅ Missing certificates: check LABC records first, then consider indemnity insurance (£150–£500)
• ✅ Notify Building Control before covering up work — failure to do so may require expensive opening up

Further Reading

• Building Regulations vs Planning Permission: What's the Difference? — the two regimes compared side by side, with a full project-type decision table
• Permitted Development Rights: The Complete UK Homeowner's Guide — PD rights grant planning consent; you still need Building Regulations approval separately
• Timber Frame vs Brick and Block UK — both structural systems follow the same Building Regs inspection regime; the pre-boarding inspection is critical for timber frame