How Extensions, Conservatories & DIY Electrics Affect an EICR (2025 UK Guide)
🏡 How Extensions, Conservatories & DIY Electrics Affect an EICR (2025 UK Guide)
Whether you’ve added a kitchen extension, conservatory, loft conversion, garage conversion or home office — your electrical system has changed. And during an EICR, these changes are inspected carefully.
Homeowners often ask:
“Will my extension or DIY wiring affect my EICR result?”
The answer is: yes — in a big way. Extensions are one of the most common reasons properties receive C2 (Unsatisfactory) EICR results in 2025.
📚 Contents
- 📌 Quick Answer
- 🔌 How Extensions Change Your Electrical System
- 🌞 Conservatories & Garden Rooms
- 🏠 Loft Conversions
- 🛠️ DIY Electrics & EICRs
- ❌ Common EICR Failures Linked to Extensions
- 📄 Do You Need Certificates for Extensions?
- 🏘️ Rules for Landlords
- 🔗 Related Guides
- ❓ FAQs
📌 Quick Answer
Yes — any extension, conservatory or DIY electrical work will be checked during an EICR.
Electricians look for:
- incorrect cable sizes
- overloaded circuits
- non-certified additions
- missing RCD protection
- unsafe junction boxes hidden in walls/floors
- incorrectly extended ring circuits
- loft and conservatory lighting faults
The more DIY or undocumented work, the higher the chance of a C2.
🔌 How Extensions Change Your Electrical System
Adding new rooms increases the electrical demand on your property. During an EICR, the electrician checks:
- whether circuits were safely extended
- whether the consumer unit can handle extra load
- if ring circuits have been broken
- if new sockets/lights comply with BS 7671
Most issues occur when extensions were added without certification.
For consumer unit checks, see:
Does an EICR Check the Consumer Unit?
🌞 Conservatories & Garden Rooms
Conservatories often contain:
- spur sockets
- DIY lighting
- underrated wiring
- outdoor-grade cabling
- heaters drawing high current
These are all inspected during an EICR.
Many conservatories fail due to:
- C2: no RCD on added sockets
- FI: inaccessible junction boxes buried in walls
- C2: spurs powering too many appliances
🏠 Loft Conversions
Loft conversions introduce new:
- lighting circuits
- additional sockets
- bathrooms (requiring RCD + IP compliance)
- fire alarm wiring (visual check)
Electricians also check:
- thermal insulation around cables
- junction boxes hidden under insulation
- wiring route through the loft structure
For more detail on loft wiring, see:
Does an EICR Check the Loft?
🛠️ DIY Electrics & EICRs
DIY wiring is one of the most common causes of C2 failures.
Examples include:
- socket fronts replaced without tightening terminals
- lights added using connector blocks
- extension leads wired into permanent circuits
- wrong cable type (0.75mm flex instead of T&E)
- incorrectly extended ring mains
DIY wiring is instantly obvious during an EICR — even if hidden.
❌ Common EICR Failures Linked to Extensions
- C2: No RCD on new sockets
- C2: Incorrect cable size for new circuits
- C2: Overloaded ring mains
- FI: Hidden junction boxes
- C2: Poorly run cables behind plasterboard
- C2: Bonding issues from new bathrooms
For fault explanations, see:
EICR Codes Explained.
📄 Do You Need Certificates for Extensions?
Yes — when you add a new circuit or modify an existing one, you should receive:
- EIC (Electrical Installation Certificate) — for new circuits
- MEIWC (Minor Works Certificate) — for small additions
- Building Control sign-off if applicable
Lack of certificates = likely FI or C2 during an EICR.
🏘️ Rules for Landlords (2025)
Landlords must ensure:
- all added sockets have RCD protection
- any loft or conservatory wiring is certified
- DIY tenant work is repaired immediately
- extensions do not overload existing circuits
- EICR every 5 years (or sooner if recommended)
🔗 Related EICR Guides
❓ Frequently Asked Questions
Will an extension make my EICR fail?
Not always — but uncertified or DIY wiring often leads to C2 faults.
Do conservatories need separate circuits?
Not always, but high-load devices may require them.
What if the extension was built years ago?
It is still inspected, regardless of age.
Does the electrician remove panels or insulation?
Only if safe and accessible — otherwise FI may be recorded.
Can I fix DIY wiring myself?
No — all remedial work must be carried out by a qualified electrician.
Extensions and DIY electrics are one of the biggest factors affecting EICR results in 2025 — understanding the rules helps ensure your property remains safe and compliant.