Granny Annexe Certificate of Lawful Development: A Step-by-Step Guide
- Mobile Annexe
- 5 hours ago
- 4 min read
If you've read our previous post on planning permission, you'll know that most granny annexes and garden annexes don't need full planning consent — instead, they're built under the Caravan Act and need a Certificate of Lawful Development (CLD) from your local council. That's the good news. The next question we usually get is: okay, so how does that actually work in practice?
Here at Mobile Annexe Ltd, we've taken this process from start to finish for clients across Essex and Hertfordshire, as well as the rest of the UK, and we currently have a 100% success rate obtaining a CLD on behalf of our clients. Here's what the process actually looks like, step by step.
What is a Certificate of Lawful Development?
A Certificate of Lawful Development is a formal, legally binding document issued by your local council confirming that a specific use or development of your property is lawful and doesn't require planning permission. For a granny annexe or garden annexe built under the Caravan Act, this is the document that gives you peace of mind — and proof, should you ever need it (for example, when selling the property) — that everything was done correctly.
It's not a rubber stamp. The council will genuinely check your proposal against the relevant rules before issuing it. But unlike a full planning application, there's no public consultation, no committee vote, and no waiting to see if a neighbour objects.
Step 1: Site survey and initial assessment
Before anything goes near the council, we carry out a full site and garden survey of your plot. This establishes:
The groundworks required for your annexe
The logistics of connecting power, water and sewage
Access to the site for tools, materials and machinery
Whether your proposed annexe size and design will fall within Caravan Act limits
This stage matters because it's where most potential problems get caught early — long before you're relying on a council decision.
Step 2: Design and specification
Once we know what your plot can support, we work through your design requirements together — layout, bedrooms, kitchen and bathroom specification, cladding, doors and windows, heating and lighting. All of this needs to be finalised (or at least clearly defined) before the CLD application goes in, since the council is assessing the lawfulness of a specific proposal, not a vague concept.
This is also the stage where we make sure the annexe stays within the size and construction rules that keep it classed as a caravan under the Act — up to 136m², depending on your plot and requirements.
Step 3: Preparing the application
The CLD application itself needs to clearly demonstrate that your proposed annexe meets the relevant legal tests — principally that it's a transportable structure under the Caravan Act, and that its use will be incidental to the main house (for example, housing an elderly parent or adult child, rather than functioning as a fully independent separate dwelling).
We prepare and submit this application on your behalf, including the supporting plans and documentation the council needs to make a decision. Because we've done this many times across different councils in Essex and Hertfordshire, as well as the rest of the UK, we know what each planning department typically expects to see — which helps avoid delays caused by incomplete or ambiguous submissions.
Step 4: Council assessment
Once submitted, your local planning authority will review the application against the rules. Timescales vary by council, but this process is generally significantly faster than a full planning application, since there's no requirement for public consultation or committee scrutiny — it's a legal determination based on the facts of the proposal, not a judgement on whether the council "likes" the plans.
Step 5: Certificate issued
If the council agrees your proposed granny annexe or garden annexe meets the criteria, they'll issue the Certificate of Lawful Development. At that point, you have formal, legal confirmation that your build doesn't require planning permission — and construction can proceed.
We keep a copy on file and provide one to you, since it's a document worth holding onto for the life of the property (mortgage lenders, buyers and solicitors may all want to see it in future).
What can cause an application to be refused or delayed?
In our experience, the most common issues are:
Ambiguous intended use. If it isn't clear the annexe will be incidental to the main house, the council may query whether it should instead be treated as a separate dwelling requiring full planning permission.
Size or design outside Caravan Act limits. Get this wrong at the design stage and it can hold up the whole application.
Incomplete documentation. Applications that don't clearly answer the council's questions the first time round inevitably take longer.
This is really the case for using an experienced company such as Mobile Annexe Ltd rather than attempting the process yourself — most of these issues are avoidable if the application is prepared properly from the outset.
Does every council treat this the same way?
Broadly, yes — the legal framework is national. But in practice, different local planning authorities can vary slightly in how they interpret and apply the rules, and in how quickly they process applications. Having worked with councils across Essex and Hertfordshire on a regular basis, we've built a good understanding of how individual planning departments tend to approach granny annexe and garden annexe applications, which helps set realistic expectations from day one.
The bottom line
Getting a Certificate of Lawful Development is usually a far simpler and faster route than full planning permission — but it still needs to be done properly, with a clear, well-documented application that leaves no room for ambiguity. Getting the site survey, design and application stages right the first time is what keeps the whole process quick and stress-free.
Ready to start your granny annexe or garden annexe project? Get in touch with Mobile Annexe Ltd for a free consultation. We cover Essex, Hertfordshire and the rest of the UK, and we'll handle your Certificate of Lawful Development application from start to finish.
📞 07770 365734 ✉️ enquiries@mobileannexe.com
Comments