With property prices rising and multigenerational living on the rise, more people across the UK — especially in the North West — are building granny annexes. But one wrong assumption can delay your build, cost you thousands, or lead to planning refusal.

This expert-backed guide breaks down the 2025 rules, including:

• What counts as a granny annexe
• Whether you need planning permission (or not)
• What Permitted Development (PD) allows
• The most common mistakes people make

Let’s help you build smart, legal, and profitably.

👵 What Exactly Is a Granny Annexe?

A granny annexe is a self-contained living space built within your property’s garden (the “curtilage” of your dwelling). It usually includes:

• A bedroom
• A bathroom
• A kitchenette or compact kitchen
• A small lounge area

It can be attached to your main house or standalone — but once it becomes independent accommodation, it moves into more complex planning territory.

💡 Why Are More Investors and Homeowners Building Them?

For Homeowners:

• Accommodate elderly parents or returning adult children
• Create a private guest space or home office
• Future-proof your home for changing needs

For Property Investors & Developers:

• Boost resale value by 7–12%
• Attract buyers looking for multigenerational setups
• Add rental income potential (where legally allowed)

Especially in locations like Cheshire, Hale, and South Manchester, this flexibility is a highly marketable asset.

📜 Do You Need Planning Permission in 2025?

In most cases: yes, especially if:

• The annexe is intended for independent living (i.e., sleeping, cooking, and washing)
• It includes a bathroom or kitchen
• It will be occupied full-time (by anyone other than guests or your household)

But there’s a big exception: some garden buildings qualify under Permitted Development (PD) rights — if strict conditions are met.

✅ Permitted Development Rules for Outbuildings (Class E, 2024)

If your proposed granny annexe is a non-self-contained outbuilding, used only for purposes “incidental to the enjoyment of the dwellinghouse”, it may qualify as Permitted Development — no planning application required.

⚠️ But every one of these rules must be met:

📍 Location Rules

• Must be within the curtilage of the dwellinghouse (your legal garden boundary)
• Must be to the rear or side — not forward of the principal elevation
• Cannot be to the side if the property is in a designated area (AONB, National Parks, World Heritage Sites, Conservation Areas)

📏 Size & Height Limits

• Single storey only
• Maximum eaves height: 2.5m
• Maximum overall height:
  • 4m with dual-pitched roof
  • 3m with flat roof or any other roof type
    
• If within 2m of a boundary, height must not exceed 2.5m
• Cumulative area of outbuildings + extensions must not cover more than 50% of the original garden land

🧱 Use Restrictions

• The outbuilding cannot be self-contained accommodation (i.e., no sleeping, bathroom, or full kitchen)
• Must not include:
  • Balconies or verandas
    
  • Microwave antenna (satellite dishes)
  • Platforms or decking higher than 300mm

🛑 Special Exceptions (No PD Rights)

• Properties that are listed buildings
• Flats, maisonettes, or commercial buildings
• Locations affected by Article 4 Directions (PD rights removed by council)
• Designated land (as above): stricter limits apply
  • Outbuildings more than 20m from house limited to 10sqm
    

⚠️ Common Pitfalls to Avoid

• Mistaking “garden room” for annexe: Self-contained annexes nearly always need permission
• Assuming your garden has no previous extensions (check what counts towards your 50%)
• Failing to get a Lawful Development Certificate — even if PD applies, this proof is vital for resale
• Not checking Article 4 Directions on your street (common in conservation areas)
  

🧭 How to Stay Legal and Build Without Stress

Here’s how to approach your annexe project the smart way:

1. Identify the Type of Use

• Incidental use = hobby room, office, gym, studio → may qualify under PD
• Primary living accommodation = granny annexe → usually needs full planning
  

2. Speak to Your Local Planning Authority (LPA)

Every council interprets PD slightly differently. Get written guidance.

3. Apply for a Lawful Development Certificate

If you’re using PD rights, this protects your project legally — especially during sales, remortgage, or enforcement disputes.

4. Work With an Experienced Architect

An expert architect (like our team at Studio Tashkeel) can:

• Confirm eligibility
• Prepare drawings for your LPA
• Optimise layout and buildability
  
• Future-proof your design for resale

💰 Will a Granny Annexe Add Value?

Yes — when designed and built properly. Here’s how:

• Boosts resale by 7–12% depending on location and finish
• Creates flexibility for multigenerational buyers
  
• Can function as a home office, guest suite, or rental (if legally approved)

According to the Office for National Statistics, over 2.5 million UK households include multiple generations — a demand trend that’s only growing.

✅ Quick Summary Checklist

 

✅  Requirement	PD-Compliant?
Within rear garden?	✔️
Under 2.5m eaves (or 2.5m near boundary)?	✔️
Not forward of main house elevation?	✔️
Non-self-contained (no bathroom/kitchen)?	✔️
Covers <50% of garden space?	✔️
Not in AONB/listed/conservation?	Depends
Sleeping/cooking facilities?	❌ Needs planning

🙋‍♀️ FAQ: Your Top Annexe Questions Answered

Can I live in an annexe full-time without planning permission?

Not under PD. If it’s a living unit, planning permission is required.

What if I already have an extension — does that count against my 50% garden rule?

Yes. Extensions, garages, and other outbuildings all count toward y

our 50% PD limit.

Do I need building regulations approval?

Often yes — especially for insulation, drainag

e, and electrics. Always check with your local Building Control.

✨ Thinking of Building a Granny Annexe in 2025?

If you’re planning a garden annexe in South Manchester, Cheshire, or anywhere in the North West, our architectural team can guide you every step — from concept to completion.

👉 Book Your FREE 15-Minute Design Call
🌐 Visit Studio Tashkeel
📩 Download the Starter Pack