One of the most common questions we hear is: 'Do I need planning permission for a granny annexe?' The answer isn't always straightforward, but understanding your options can save you time and money. This guide explains the two main routes: permitted development and the Caravan Act.
The Short Answer
It depends on your property, location, and which route you choose. There are two main options:
- Build under permitted development rights (subject to size and location restrictions)
- Build under the Caravan Act as a mobile home (often no planning required)
Permitted Development Rights
Under permitted development, you can build outbuildings without planning permission if you meet certain criteria:
- The annexe covers no more than 50% of your garden
- It's no higher than 4m (2.5m if within 2m of boundary)
- It's not in front of the principal elevation
- You're not in a conservation area, AONB, or listed building
- The building is for 'incidental' use to the main house
The Caravan Act Route
This is often the better option for granny annexes. Under the Caravan Sites and Control of Development Act 1960, a structure can be classified as a mobile home if:
- It's designed to be movable (in one or two sections)
- It meets caravan dimensions (max 20m x 6.8m)
- It's for residential use ancillary to the main dwelling
- It's occupied by family members or dependents
Benefits of the Caravan Act Route
There are significant advantages to building under the Caravan Act:
- Often no planning permission required
- Zero VAT (saving 20% on the build cost)
- Faster installation (no waiting for planning)
- Can be relocated if needed
- Less bureaucracy and lower costs
When You Will Need Planning
Some situations always require planning permission:
- If you want a permanent, non-movable structure
- If the annexe will have a separate postal address
- In conservation areas or near listed buildings
- If you're in an Area of Outstanding Natural Beauty
- If the occupant isn't a family member or dependent
How We Can Help
At Grannexe, we handle all the planning complexity for you. We'll assess your property, advise on the best route, and manage all applications or certifications required. Our experience means we know what works and what doesn't, saving you time and stress.
Conclusion
The planning question isn't always simple, but with the right guidance, it's manageable. The Caravan Act route offers significant benefits for most families, including zero VAT and often no planning permission. We'll help you choose the right path for your property and handle all the details. Contact us for a free consultation and we'll explain your options clearly.