An easy-to-understand guide to UK building regulations in 2026, explaining energy efficiency, ventilation, overheating and fire safety rules for extensions and loft conversions.
Building Regulations in 2026: What’s Changed and Why It Matters
Building regulations exist to ensure homes are safe, energy-efficient and comfortable to live in. In 2026, regulations place greater emphasis on energy performance, indoor air quality, overheating prevention and fire safety—particularly for extensions and loft conversions.
- Stricter energy efficiency standards (Part L)
- Improved ventilation requirements (Part F)
- Mandatory overheating risk control (Part O)
| Key Building Regulations Affecting Home Extensions |
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Part L – Energy efficiency and insulation Part F – Ventilation and indoor air quality Part O – Overheating prevention Part B – Fire safety and escape routes |
Building regulations approval is required regardless of whether planning permission is needed. For most projects, early coordination between design, structure and compliance prevents costly redesigns later.
Learn more about compliance support on our building regulations service page or explore compliant designs for conversions on our loft conversion services page.
Building Regulations FAQs
Common questions homeowners ask about building regs in 2026.
Do building regulations apply to permitted development?
Yes. Even if planning permission is not required, all structural works must comply with building regulations.
What is Part L of the building regulations?
Part L focuses on energy efficiency, requiring higher insulation standards and improved thermal performance.
Why is Part O important?
Part O reduces overheating risk by requiring better shading, glazing control and ventilation strategies.
Do loft conversions need fire upgrades?
Yes. Fire doors, protected staircases and escape routes are often required for loft conversions.
Who signs off building regulations?
Approval is given by building control, either through the local authority or an approved inspector.
Can poor compliance affect resale value?
Yes. Missing completion certificates can delay or derail property sales.
