Planning & Regulations
The rules, regulations, and tax benefits you need to know about before building a granny annexe.
Planning Permission
Often not required under Permitted Development
Caravan Act
Classification that means zero VAT and simpler planning
Zero VAT
Save 20% immediately on your build cost
Building Regs
Different requirements for mobile structures
Planning Permission
Most granny annexes can be built under Permitted Development rights, which means you don't need full planning permission. However, you must meet specific criteria.
Permitted Development Requirements
- Size limit: Annexe + other outbuildings cannot exceed 50% of garden area
- Height limit: Maximum 2.5m if within 2m of boundary, 4m elsewhere
- Ancillary use: Must be incidental to main dwelling (for family, not rental)
- No separate dwelling: Cannot have separate address or be sold separately
When Full Planning Is Required
You'll need to apply for full planning permission if:
- Your property is in a Conservation Area
- Your home is a listed building
- You're in an Area of Outstanding Natural Beauty (AONB)
- Your property is in a National Park
- Permitted Development rights have been removed
Certificate of Lawfulness
Even under Permitted Development, we recommend applying for a Certificate of Lawful Development (£200-£500). This confirms your build is compliant and provides official documentation for mortgage/insurance purposes.
The Caravan Act 1960
The Caravan Act 1960 classifies certain mobile structures as "caravans" rather than buildings. This offers significant financial and planning advantages.
Benefits
- Zero VAT: Save 20% on build cost
- Easier planning: Often falls under PD
- Flexibility: Technically movable
- Property value: Can relocate if you move
Requirements
- Maximum 20m x 6.8m dimensions
- Deliverable in max 2 sections
- Must be movable (even if disassembled)
- For human habitation
VAT Savings Example
Building Regulations
Structures complying with the Caravan Act have different Building Regulations requirements than permanent buildings.
What We Provide
- High standards: Built to exceed building regulations for insulation, structure, and safety
- Electrical certification: Full Part P compliance with certified electrician
- Gas Safe: All gas work certified by Gas Safe registered engineers
- Structural warranty: 10-year guarantee on build quality
Note: Groundworks (foundations, drainage) may require Building Control notification depending on your local authority. We handle all necessary applications on your behalf.
We Handle the Paperwork
Planning and regulations are our job, not yours. Here's what we take care of.
Free Site Assessment
We'll determine if your project qualifies for Permitted Development or needs full planning
Application Submission
We prepare and submit all Certificate of Lawfulness or planning applications
Council Liaison
We communicate directly with your local planning authority on your behalf
Full Documentation
We provide all necessary certificates, warranties, and compliance documentation
Have Questions About Planning?
Every property is different. Get in touch for a free consultation and we'll tell you which planning route applies to your situation.