🏗️ 2022 Changes to Building Regulations Part L for Home Extensions **Updated**
By Kieran Atherton, Director of Melrose Designs
Wigan-based architectural designer specialising in home extensions, loft conversions, and Building Regulations drawings across the North West.
—
📘 Pillar Page: Understanding Building Regulations for Home Extensions (2022 Updates)
If you’re planning a home extension or renovation, it’s essential to understand how the 2022 changes to Building Regulations Part L affect your project.
These updates are part of the government’s drive towards net-zero carbon homes and have major implications for insulation, energy efficiency, and building design.
To help you navigate the changes, we’ve created a comprehensive Building Regulations hub:
Part L Explained: Energy Efficiency for Extensions
Understanding Part F – Ventilation Requirements
How Part O Prevents Overheating in Modern Homes
These pages link together as part of our Building Regulations Pillar Series, designed to give homeowners and builders clear, compliant information in one place.
—
🧱 What Is Building Regulations Part L?
Building Regulations Part L sets the standards for thermal performance and energy efficiency in UK buildings.
The 2022 update introduced stricter targets to reduce heat loss and carbon emissions — a vital step towards the Future Homes Standard (2025).
Why Were the Rules Changed?
- Support the UK’s net-zero by 2050 target
- Cut energy use and carbon emissions from homes
- Improve thermal comfort and reduce fuel bills
—
📊 Key 2022 U-Value Updates for Extensions
A U-value measures how much heat escapes through an element — the lower, the better.
| Building Element | Old U-Value (W/m²K) | New U-Value (W/m²K) (July 2022 Update) |
|---|---|---|
| Roofs | 0.18 / 0.16 (depending on type) | 0.15 |
| Walls | 0.28 | 0.18 |
| Floors | 0.22 | 0.18 |
| Windows | 1.6 | 1.4 |
| Glazed Doors | 1.8 | 1.4 |
| Rooflights | 2.20 | 2.20 |
What This Means:
- Thicker insulation in walls, floors, and roofs
- Better glazing performance
- Improved airtightness (now mandatory testing)
- Compatibility with low-carbon heating systems
—
🧰 Real-World Example: How These Changes Affect a Typical Extension
Before July 2022, a standard single-storey brick extension could achieve compliance with:
- 100 mm cavity wall
- 50 mm insulation
- Under the new regulations, the same design now needs:
- 140 mm cavity with 90 mm insulation
- 50 mm extra insulation under rafters
- Longer wall ties and deeper reveals
👉 These adjustments improve energy efficiency but slightly increase build costs and wall thickness.
—
💡 How the Changes Impact Homeowners & Builders
Impact Description
💷 Higher Costs More insulation materials and thicker wall construction
⏱️ Longer Approval Times Building Control requires more detailed drawings
🌿 Better Energy Performance Lower heating bills and improved comfort
At Melrose Designs, we translate these complex requirements into clear, compliant drawings for approval by Wigan, St Helens, and local councils.
—
🔍 Related Building Regulation Updates (2022)
- Part F – Ventilation Standards
- Improved extraction in kitchens and bathrooms
- Balanced airflow to reduce condensation and mould
- Part O – Overheating Prevention
- Thermal modelling for overheating risk
- Solar-gain limits for south-facing glazing
- Part S – EV Charging
- New builds and extensions must include 7 kW untethered chargers
- Ducting infrastructure required for future-proofing
—
🏗️ How to Get Building Regulations Approval (Step-by-Step)
- Consultation – Discuss your plans with a Building Regulations expert
- Measured Survey – Gather precise property data
- Technical Drawings – We prepare compliant Part L drawings
- Submission – Send to your local authority or private inspector
- Construction Stage Inspections – Verify compliance during the build
—
🧠 Why Choose Melrose Designs?
Melrose Designs provides architectural design services and Building Regulations drawings for home extensions across Wigan, St Helens, Warrington, and the North West.
What We Offer
✅ Expert advice on Part L compliance and insulation design
✅ Fast, affordable Building Regulations drawings
✅ Builder-ready plans for accurate pricing
✅ Step-by-step support until approval
Get Your Building Regulations Drawings Approved Today!
Planning an extension or renovation? Need Building Regs drawings in St Helens? Our team at Melrose Designs ensures your project meets all new 2022 Building Regulations standards.
Contact us today for expert guidance and a free consultation!
“Our goal is to make home design simple, affordable, and fully compliant — so you can build with confidence.”
— Kieran Atherton, Director of Melrose Designs.