Planning Permission Rules for Single-Storey Extensions in Cardiff: Your Complete Guide
Thinking about adding a single-storey extension in Cardiff? You’ll want to get a handle on consent, regulations, and how it all fits with your home’s look. Getting the right approvals means a smoother build, protects your investment, and keeps your plans compliant from day one. This guide breaks down the essentials of planning permission, permitted development rights, how to apply, building regulations, costs, and other key things to consider. If you’re still weighing up different ways to add space, start with our main guide to home extensions for a clear overview of the options.
Understanding Planning Permission and Permitted Development Rights for Single-Storey Extensions in Cardiff
Planning permission is essentially official approval for specific building works, ensuring your project aligns with local policies and considers neighbour impact. Permitted development rights, on the other hand, offer automatic consent for certain extensions that meet predefined limits, which can significantly speed up your project and cut down on fees. Knowing the ins and outs of both systems will help you choose the most efficient approval route and steer clear of any enforcement issues.
What is Planning Permission, and When Do You Need It?
Planning permission is the formal consent you get from the local authority confirming that your proposed building project aligns with relevant planning policies. You’ll need it if your extension goes beyond the limits set by permitted development rights, if your property is affected by restrictions, or if the proposed changes create a clear planning impact. For a broader explanation of when consent is required, see our guide to planning permission for extensions.
How Do Permitted Development Rights Apply to Single-Storey Extensions in Wales?
Permitted development rights (PDR) are part of national planning rules that allow certain home improvements without requiring a full planning application. For many single-storey extensions, PDR means you automatically have consent, provided you stick to the specified limits on size, height, boundaries, and materials. If you want a clearer breakdown of what’s typically allowed, you can also read our explainer on permitted development rights.
What Are the Key Conditions for Permitted Development Rights on Cardiff Extensions?
Here’s a rundown of the main PDR criteria for single-storey additions across Wales:
- Maximum projection from the rear wall: 4 metres for detached homes, 3 metres for others
- Maximum eaves and ridge height: 3 metres for eaves if within 2 metres of a boundary, 4 metres for the ridge on dual-pitched roofs
- Overall site coverage: Your extension shouldn’t take up more than 50% of the original garden area
- Materials: they should be similar in appearance to the existing house
- Projections: verandas, balconies, or raised platforms are not allowed under PDR
Planning permission: extensions
Official guidance from the Welsh Government details the conditions for permitted development rights for single-storey extensions. These include limits on rear projection (up to 4 metres), overall height (not exceeding 4 metres), and eaves height (not exceeding 3 metres if within 2 metres of a boundary). The guidance also clarifies that verandas, balconies, or raised platforms are not permitted under these rights.
Sticking to these conditions means you may not need full planning permission. However, it’s still a good idea to apply for a Certificate of Lawfulness to officially confirm the works are lawful before you start on site.
Specific Rules for Rear Single-Storey Extensions
Rear extensions often benefit the most from PDR, but you must ensure they don’t compromise your neighbours’ light and privacy. The key requirements include:
- Projection limits of 3 metres (semi-detached/terraced) or 4 metres (detached)
- Eaves no higher than 3 metres if the extension is within 2 metres of a side boundary
- No step-downs or cantilevered upper sections
- Keep boundary treatments sensible to avoid neighbour conflict
Specific Rules for Side Single-Storey Extensions
Side extensions built under PDR shouldn’t negatively affect the street scene or building lines. The conditions include:
- The width shouldn’t be more than half the original house frontage
- Maximum height is 4 metres for dual-pitched roofs or 3 metres for flat roofs
- Side-facing windows close to a boundary may need obscure glazing
- The roof pitch and materials should be in keeping with the main house
When Are Permitted Development Rights Restricted or Removed in Cardiff?
Your permitted development rights can be limited or removed in several situations:
- Conservation areas
- Listed building status
- Article 4 Directions
- Original planning conditions that restrict household development
In any of these cases, you’ll usually need to apply for full planning permission (and sometimes additional consents).
When Full Planning Permission is Necessary for Single-Storey Extensions in Cardiff
You’ll need to apply for full planning permission whenever your extension exceeds the PDR limits or is located in a protected/restricted context. This ensures a proper review of design, neighbour impact, and site constraints.
Which Properties and Situations Require Full Planning Permission?
You’ll typically need full consent if:
- Your rear projection goes beyond 4 metres (detached) or 3 metres (other house types).
- The roof height exceeds typical PDR maxima.
- Your home is affected by conservation controls or other restrictions.
- Previous planning conditions remove permitted development rights.
How Do Cardiff Council’s Local Development Plan and Policies Affect Extensions?
Local planning policies influence what’s acceptable in terms of design quality, neighbourhood character, and how the extension sits on the plot. Even where development is possible in principle, poorly proportioned designs or unsuitable materials can cause delays or refusals.
What is the Role of Article 4 Directions in Removing Permitted Development Rights?
Article 4 Directions are tools that can remove permitted development rights in specific areas, meaning certain works require planning permission even if they’d normally be allowed. If you suspect restrictions apply, it’s sensible to confirm early to avoid designing something you can’t build.
Navigating the Planning Application Process
Submitting a planning application involves a clear set of steps designed to manage expectations around documentation, consultation, and decision timelines.
What is Pre-Application Advice and Why Is It Important?
Pre-application advice helps identify likely issues early (neighbour impact, scale, design approach, documentation). It can reduce the risk of refusal and cut down on back-and-forth during the formal process.
How Do You Submit a Planning Application for a Single-Storey Extension?
Applications usually require drawings, plans, and supporting documentation. If you want an idea of what the process looks like from start to finish (including what’s typically prepared and submitted), you can also view our planning application process.
What Are the Typical Decision Timelines and Outcomes?
Householder applications are commonly decided within the standard determination period once validated. Outcomes include approval (sometimes with conditions), refusal (with reasons), or approval subject to minor amendments.
What is a Certificate of Lawfulness and When Should You Apply?
A Certificate of Lawfulness is official confirmation that your proposed works qualify under permitted development rights. It’s particularly useful when your plans are close to limits, when previous alterations complicate the situation, or when you want paperwork for future sale/valuation.
Building Regulations for Single-Storey Extensions in Cardiff
Building regulations are separate from planning permission and focus on ensuring structural safety, energy efficiency, ventilation, drainage, and fire protection for your extension.
What Are the Key Building Regulation Requirements for Single-Storey Extensions in Wales?
- Foundations and load-bearing walls
- Thermal performance (insulation and glazing)
- Drainage and ventilation
- Fire safety
- Electrical and plumbing compliance and certification
How Does the Building Control Approval Process Work in Cardiff?
- Submit either a building notice or a full plans application.
- Receive feedback / acceptance.
- Book inspections at key stages.
- Receive a completion certificate after final sign-off.
How Do Building Regulations Differ from Planning Permission?
Planning focuses on policy and neighbour/street impact; building regulations focus on technical safety and performance. You often run both processes alongside each other, but they are separate approvals.
Costs Associated with Planning Permission and Building Control for Extensions
Understanding fees early helps you set a realistic budget and avoid surprises.
How Much Does a Planning Application Cost in Cardiff?
| Fee Type | Cost | Applies To |
|---|---|---|
| Householder planning consent | £206 | Extensions, conservatories, and other alterations to a single dwelling |
| Lawful development certificate | £103 | Confirmation of permitted development rights for proposed works |
A Guide to the Fees for Planning Applications in Wales
Official guidance on planning application fees in Wales indicates that a householder planning consent for extensions or alterations to a single dwelling costs £206. For a Certificate of Lawfulness for proposed works, the fee is £103 based on the householder application fee.
What Are Typical Architectural and Professional Fees?
Fees for architectural design and consultancy services for single-storey extensions typically range from 5% to 10% of the total construction cost. These professional services can include concept design, technical drawings, planning submissions, and building regulations information.
What Are Building Control Fees and Other Associated Costs?
Building Control charges are usually based on the estimated cost of your project. You might also incur additional costs for structural engineer calculations, party wall awards, or surveys.
Key Considerations for Homeowners Before Starting a Single-Storey Extension
A successful extension project balances technical compliance with good neighbourly relations and seamless aesthetic integration.
How Do Neighbour Consultation and the Party Wall Act Affect Your Extension?
Having informal chats with neighbours before submitting can reduce objections. If your planned works affect shared walls or boundaries, you may need a formal party wall process — handle it early to avoid delays and disputes.
Why is Matching Design and Materials Important for Planning Approval?
Using materials and proportions that sit well with the existing house improves the chances of a smooth planning decision and helps the extension look “like it belongs”.
What Are Common Pitfalls and How Can You Avoid Them?
- Boundary encroachments: double-check measurements and ownership lines.
- Drainage/soakaway needs: confirm requirements early.
- Restrictions: check whether conservation controls or similar constraints apply.
- Inspection timing: book Building Control visits in advance.
Frequently Asked Questions
Do I Need Planning Permission for a Single-Storey Extension?
Many single-storey extensions can be done under permitted development rights if they stay within size/height limits and your property isn’t restricted. Where it’s close to the limits, a Certificate of Lawfulness can give you confidence.
How Close Can My Extension Be to the Boundary Under Permitted Development?
Where an extension is within 2 metres of a boundary, the eaves height is commonly restricted to 3 metres under permitted development rules.
Can I Build a Veranda or Raised Platform Without Permission?
Verandas, balconies, and raised platforms are excluded from permitted development rights and typically need planning permission.
How Long Does the Planning Permission Process Take?
Householder applications are commonly decided within the standard determination period once validated, though complexity and requests for clarification can affect timings.
What Happens If My Planning Application Is Refused?
You can revise the proposal to address the reasons for refusal and resubmit, or appeal. Good feasibility checks and a clear submission reduce the chances of refusal.
By planning carefully, following official guidance, and getting the right support, you’ll be in the best position for approval, cost certainty, and a well-executed build.
