Building Regulations Approval Explained – What Every Homeowner Must Know

UK homeowner discussing building plans with a Building Control officer in front of a home extension under construction, illustrating the Building Regulations Approval process.

Building Regulations Approval is one of those phrases that can make any homeowner pause — especially if you’re planning an extension or loft conversion. But don’t worry. Once you understand what’s required, getting approval isn’t as complex as it sounds. This guide walks you through exactly what Building Regulations Approval means, why you need it, and how to get it right first time.

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What is Building Regulations Approval?

Building Regulations Approval confirms that your extension, loft conversion, or internal alteration meets the safety, energy efficiency, and accessibility standards set by the UK Government. These rules protect you, your family, and any future occupants — ensuring that every structure built in England and Wales is safe and compliant.

Note: Building Regulations Approval is completely separate from planning permission. Even if your project doesn’t need planning consent, it almost always needs Building Regulations Approval.

Why it matters for extensions and conversions

If you’re adding space to your home — whether that’s a rear extension, garage conversion, or loft conversion — Building Regulations Approval ensures:

  • Structural safety (e.g., beams, walls, and foundations are correctly sized)
  • Fire safety and escape routes meet Part B requirements
  • Thermal performance meets Part L energy standards
  • Proper drainage and ventilation systems are installed
  • Electrical and plumbing work is safely designed and certified

Failing to get approval can cause serious problems later — from failed Building Control inspections to delays when selling your home. Mortgage lenders and solicitors will ask for your Completion Certificate before completing any sale.

The two main routes to Building Regulations Approval

Homeowners can apply for Building Regulations Approval through one of two routes:

1. Full Plans Application

This is the most common route for extensions and conversions. You submit detailed Building Regulations drawings for review before starting work. The Building Control officer checks your design for compliance with all relevant parts of the regulations. Once approved, you’ll receive a formal notice confirming permission to begin.

Tip: This route gives peace of mind — problems are identified before work starts, reducing delays and costly changes later.

2. Building Notice

For smaller works (like non-structural alterations), you may choose a Building Notice. You don’t need to submit full drawings, but your builder must follow the rules carefully as inspections happen throughout construction. This route is faster but riskier, as any non-compliance could require corrections after the fact.

Important: Building Notices aren’t usually accepted for extensions close to sewers or boundary walls. Always check with your local Building Control before choosing this route.

Not sure which approval route to take?

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What drawings and documents you’ll need

To obtain Building Regulations Approval, you’ll need detailed technical drawings showing how your extension or conversion will comply with the rules. These usually include:

  • Existing and proposed floor plans, elevations, and sections
  • Structural calculations (if new beams or openings are involved)
  • Thermal and insulation details
  • Drainage layouts and specification notes
  • Construction notes that reference each Part of the Building Regulations

At Plans Made Easy, we prepare all these drawings and submit them directly to Building Control for you — ensuring everything meets national standards from the outset.

Typical timelines and costs

Note: Timescales vary by council, but generally:
  • Full Plans Approval: 3–6 weeks for review and decision
  • Building Notice: Can begin within 48 hours of submission

Fees depend on the size and type of project. Most local authorities charge between £200–£700 for extensions, and private Building Control bodies often quote fixed packages. The design stage (drawings and notes) is usually handled by your designer or planning consultant.

Common mistakes homeowners make

  • Starting work before approval is issued
  • Using “old” drawings that don’t reflect the build
  • Ignoring Building Control site inspections
  • Not keeping copies of certificates (especially for electrics and gas)
  • Assuming “permitted development” means “no regulations needed”
Gotcha: Even if your project qualifies under Permitted Development, it must still comply with the Building Regulations. Skipping this step can result in enforcement action or expensive retrospective applications.

How to get Building Regulations Approval step-by-step

  1. Contact your designer (or us) for compliant Building Regulations drawings.
  2. Submit your Full Plans or Building Notice application to Building Control.
  3. Wait for confirmation that your application has been validated.
  4. Start work only after you’ve received approval or acknowledgment to proceed.
  5. Book inspections at key stages — foundation, drainage, insulation, and final completion.
  6. Receive your Completion Certificate once work passes final inspection.
Quick Costs Snapshot
  • Typical Approval Fee:£200–£700 (depending on council and project size)
  • Average Timescale:3–6 weeks (Full Plans route)
  • Documents Required:Plans, sections, construction notes, structural calcs, insulation details
  • Completion Certificate:Issued after final inspection and approval

Frequently Asked Questions

Do I need Building Regulations Approval for a small extension?

Yes — almost all extensions require approval, even if they fall under permitted development rights. The regulations focus on how it’s built, not how big it is.

Can I use private Building Control instead of the council?

Yes, Approved Inspectors can handle your Building Regulations application. They’re often faster than councils but charge similar fees.

What happens if I skip Building Regulations Approval?

You risk enforcement action, insurance issues, and difficulty selling your property. Solicitors will require proof of compliance during conveyancing.

When should I apply for approval?

Before starting any structural work. Submitting early allows time for review and avoids site delays.

Next Steps & Useful Guides

Key Facts Snapshot – Building Regulations Approval
  • Applies to:Extensions, conversions, major structural or insulation changes
  • Legal requirement:Yes – under the Building Act 1984
  • Governing authority:Local authority Building Control or Approved Inspector
  • Typical timeframe:3–6 weeks for Full Plans approval
  • Final outcome:Building Regulations Completion Certificate

For further guidance, visit the Planning Portal or GOV.UK for national Building Regulations policy and requirements.

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Article review and update information:
Last updated: November 7, 2025

Published: November 8, 2025

✅ Reviewed by Stuart Cronshaw   

Stuart Cronshaw – Plans Made Easy

Written & Reviewed by Stuart Cronshaw

Stuart is the founder of Plans Made Easy and an experienced architectural consultant with over 30 years in planning drawings, building regulations, and residential development. He has prepared hundreds of successful applications across the UK, helping homeowners get projects approved quickly and with confidence.

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