The Beginner’s Guide to UK Planning Permission: What You Can and Can’t Do

If you’ve ever looked at a property and thought “I could turn that garage into a loft” or “What if I split this house into two flats?”, the first question you’ll hear is: “Do I need planning permission?”

In the UK, planning permission is the tool local councils use to control how land and buildings are developed. Getting it right (or knowing when you don’t need it) can save you months of delay, money, and a hefty dose of frustration. This guide breaks down the basics, the do‑and‑don’ts, and the steps you need to follow, all written in plain English for absolute beginners.

1. Planning Permission 101 – What Is It, Anyway?

Term	What It Means	Why It Matters
Planning Permission	Formal consent from your Local Planning Authority (LPA) to carry out a specific development (new building, extension, change of use, demolition, etc.).	Without it, you could be forced to halt works, undo them, or even face a fine.
Permitted Development (PD)	A set of nationally‑approved rights that let you carry out certain works without applying for full planning permission (e.g., most single‑storey rear extensions).	Saves time and paperwork, but you still need to respect size, height and other limits.
Building Regulations	Technical standards for health & safety, energy efficiency, fire safety, etc. Separate from planning permission.	You may need both planning permission and a building regulations approval, or just the latter.
Local Planning Authority (LPA)	Usually your district, borough, or city council’s planning department.	They decide whether your proposal meets local policies and national law.

Quick Takeaway

• Planning permission = “Can I do it?”
• Permitted development = “I can do it, as long as I stay within limits.”
• Building regulations = “How do I do it safely?”

2. When Do You Definitely Need Planning Permission?

Development Type	Typical Scenarios	Why Permission Is Required
New buildings	Adding a new house, garage, or outbuilding > 15 m² (or 30 m² in a conservation area).	Impacts land use, visual character, and local infrastructure.
Major extensions	Two‑storey rear or side extensions, or any addition that exceeds PD size limits.	Alters the building’s footprint and may affect neighbours.
Change of use	Turning a shop into a dwelling, a house into a B‑class office, etc.	Different uses have different impacts (traffic, noise, services).
Demolition	Removing a house or any structure > 10 m².	Affects heritage, open space, and community character.
Listed buildings & Conservation Areas	Any alteration to a listed building or works that affect the external appearance of a property within a designated conservation area.	Extra historic protection; the LPA will scrutinise heavily.
Large commercial projects	New shops, restaurants, industrial units, or sizable refurbishments.	Significant effect on employment, traffic, and local economy.

Rule of thumb: If the work adds something new, changes the use, or significantly alters the size/height of an existing structure, you’ll probably need full planning permission.

3. The Most Common Permitted Development Rights (What You Can Usually Do)

Note: PD rights are subject to “Article 4 Directions” – local councils can remove PD rights in specific areas (e.g., historic town centres). Always double‑check your LPA’s website.

PD Right	Typical Limits (England)	Example Projects
Single‑storey rear extensions	Up to 4 m from the rear wall (or 3 m if the house is at the rear boundary). Max height 4 m.	Kitchen extension, garden office.
Two‑storey rear extensions (house only)	No rear extension exceeding 3 m from the original rear wall (or 2 m if within 2 m of a neighbour’s property). Max height 4 m.	Adding a second floor at the back.
Side extensions	Max height 4 m (or 3 m for a side extension that is also a rear extension).	Extending the side of a bungalow to a larger living room.
Loft conversions	No more than 40 % of the roof space can be converted if the building is a house; 50 % for flats. Max volume 40 m³.	Adding a bedroom under the roof.
Outbuildings	Up to 50 % of the total area of the original house (or 30 % for a listed building). Max height 2.5 m for a single storey, 4 m for a two‑storey (if not within 20 m of the house).	Garden sheds, detached garages, small summer houses.
Change of use (domestic)	“Use class C3 (dwelling houses)” to “C4 (houses in multiple occupation)” – subject to size & fire‑safety checks.	Turning a single‑family home into a small HMO.
Small commercial changes	Certain limited changes of use (e.g., from a shop to a café) can fall under PD if floor area < 280 m².	Converting a corner shop to a coffee shop.

How to Check If You’re Within PD Limits

1. Measure – Get accurate dimensions of your property, the proposed addition, and distances to boundaries.
2. Use the LPA’s PD calculator – Most councils have an online “Permitted Development Right” checker.
3. Check for any Article 4 directions – Look under “Planning Policy” on the council website.

4. The Planning Permission Process – Step by Step

Step	What You Do	Approximate Timescale
1. Pre‑application enquiry (optional)	Contact the planning department with sketches; they’ll give informal feedback.	1‑2 weeks (if you request).
2. Prepare a full application	Complete the Planning Application Form (PINS 1), pay the fee (£462 for a house, £206 for a small extension, plus any additional fees). Provide: • Site plans • Elevations • Design & Access Statement (if required) • Supporting documents (e.g., heritage statements).	–
3. Submit	Online via the Planning Portal (or paper to the LPA).	Immediate receipt confirmation.
4. Validation	LPA checks the application is complete. If anything’s missing, they’ll ask for clarification.	Usually within 5 working days.
5. Public consultation	Notice is posted on the site; neighbours (within 300 m) are invited to comment.	21 days for most residential applications.
6. Decision	Council’s planning officers (or a planning committee for larger schemes) decide.	Statutory 8‑week period (8 weeks for most applications, 13 weeks for major ones).
7. Decision notice	You receive a written notice – either grant, conditional grant, or refusal.	–
8. If granted – Start work	You have 3 years (or 4 for change‑of‑use) to begin development, otherwise permission lapses.	–
9. Appeal (if refused)	Submit an appeal to the Planning Inspectorate within 6 weeks of the decision.	Typically 8‑12 weeks for the inspectorate to decide.

Pro‑Tip: Keep a Timeline Sheet

Milestone	Target Date	Status
Pre‑app enquiry	10 Mar 2026	Done
Submit full app	30 Mar 2026	Pending
Validation deadline	7 Apr 2026	–
Public consultation ends	28 Apr 2026	–
Decision due	26 Jun 2026	–

Having a visual schedule helps you stay on top of deadlines and prevents permission from lapsing.

5. What Happens If You Build Without Permission?

Consequence	Typical Scenarios
Enforcement notice	Council orders you to stop work or demolish the unauthorised part.
Legal action	You could be taken to court and fined up to £20,000 (or more for serious breaches).
Impact on resale	A property with unauthorised works can be difficult to sell; buyers and lenders often demand retrospective planning consent.
Insurance problems	Many insurers will refuse a claim for damage to unauthorised structures.
Neighbour disputes	Unapproved extensions often spark neighbour complaints, leading to legal headaches.

Bottom line: Never assume “nobody will notice.” The LPA regularly carries out spot checks, and neighbours can report you at any time.

6. Special Situations You Need to Know

Situation	What You Can (or Can’t) Do	Key Advice
Listed buildings	Almost any alteration needs full planning permission and listed building consent.	Contact the Historic England guidance and your LPA early.
Conservation Areas	PD rights are more restrictive – e.g., side extensions often need permission.	Check the council’s Conservation Area Appraisal.
Article 4 Directions	PD rights are withdrawn in designated zones (often historic town centres).	Assume you need permission unless the council explicitly confirms otherwise.
House in Multiple Occupation (HMO)	Converting a house to an HMO > 5 tenants requires full planning permission (use class C4).	Also check HMO licensing requirements.
Agricultural land	Building a barn or storage may need full permission unless it qualifies as a ‘temporary structure’.	Talk to the Rural Development Service of your LPA.
Temporary structures (e.g., garden sheds, portable cabins)	Usually exempt if < 15 m², < 2.5 m high, and used for < 28 days a year.	Keep a written record of dates and dimensions in case of inspection.

7. Frequently Asked Questions (FAQ)

Q1. I just want a small shed. Do I need permission?
If it’s under 15 m², under 2.5 m high, and not within 2 m of the main house (or a listed building), it’s generally exempt. Still check for any local Article 4 directions.

Q2. My neighbour says I need permission for my rear extension, but I think it’s PD. Who’s right?
Check the exact measurements against the PD limits. If you’re within limits, you’re legally allowed. However, you must still comply with building regulations and party wall obligations under the Party Wall Act 1996.

Q3. The council gave me a conditional planning permission. What does that mean?
A conditional permission means the council will grant approval once you satisfy certain conditions (e.g., submit a detailed design, provide a drainage plan). You must meet those before starting work, otherwise the permission lapses.

Q4. I’m buying a house that already has an extension. Do I need to get permission again?
Only if the extension was built without permission or outside the PD rights. Ask the seller for the planning permission documents and check the LPA’s planning portal for any enforcement notices. If the work was illegal, you may need to regularise it after purchase.

Q5. Can I appeal a decision that I think is unfair?
Yes – within 6 weeks of the decision notice, you can submit an appeal to the Planning Inspectorate. You’ll need to state why the decision was wrong and provide supporting evidence.

8. Quick Checklist – “Do I Need Planning Permission?”

1. What is the work? (new build, extension, change of use, demolition)
2. Measure it. Compare to PD limits.
3. Check your LPA’s website for:
   • PD rights table (usually under “Planning Policy”)
   • Article 4 directions for your postcode
   • Conservation area or listed building status
4. Consult the Planning Portal – use the “Check if you need planning permission” wizard.
5. If still unsure, make a pre‑application enquiry (free or low‑cost).

9. Where to Get Help

Resource	What It Offers
Planning Portal (www.planningportal.co.uk)	Online forms, fee calculator, PD checker, guidance notes.
Your Local Planning Authority website	Area‑specific policies, Article 4 maps, contact details for the Planning Service.
Citizen Advice Bureau	Free advice on planning disputes and enforcement notices.
Chartered Surveyors / Planning Consultants	Professional advice, especially for larger schemes or where PD rights are ambiguous.
Neighbourhood Planning Groups	Community‑led plans can affect what’s allowed in your area.

10. Final Thoughts – Take the Fear Out of Planning Permission

Planning permission can feel like a bureaucratic maze, but remember:

• Most everyday home improvements are covered by Permitted Development.
• If you’re close to the limits, or the property is in a special area, it’s worth double‑checking.
• The earlier you talk to your LPA, the smoother the process.

By understanding the basics, measuring carefully, and following the steps outlined above, you’ll be able to turn your home‑improvement ideas into reality—legally, safely, and without nasty surprises.

Ready to get started?

1. Grab a tape measure and sketch your idea.
2. Use the Planning Portal PD checker now (it takes 2‑3 minutes).
3. If you hit a red flag, book a quick phone call with your council’s planning officers.

Happy planning, and may your next extension be the talk of the neighbourhood—for all the right reasons!