Planning Permission For Timber Garden Buildings

TRJ Construction Ltd • 1 June 2020

 

All timber garden structures, including Garden Sheds, Summerhouses and Garages are subject to planning permission rules; however, the good news is that the majority of our buildings won't actually require planning permission for installation.

 


 

Whether you need planning permission or not will all depend on where you wish to place the building in your garden and if you should live in an area that has been designated as a national park or similar. Providing certain criteria are met and the building is considered permitted development, you can proceed without needing permission.

 

Garden Buildings are considered Permitted Development and do NOT require planning permission as long as:

 

- The building is to be placed less than 2.0m from the boundary of the property with a maximum overall height of no more than 2.5m from existing ground level. If you want a large building this close to the boundary, which, as a general rule, will have a taller roof height, we can lower the overall roof height of the majority of our apex roof buildings, and our garden buildings with pent roofs are all under 2.5m in height as well.

 

-The building is to be placed more than 2.0m from the boundary of the property. If this is the case, a single storey garden building can have a maximum eave height of 2.5m, which is a maximum overall height of 4.0m for a dual-pitched roof and 3.0m maximum overall height for a pent roofed building. If you would like the overall height to be taller than these roof heights, you will need to apply for planning permission.

 

-The building is not to be used as self-contained living accommodation or have an antenna*.

 

While this criterion is one of the rules for outbuildings, Crane Garden Buildings does NOT sell buildings for use as self-contained living accommodation; this is because buildings for this purpose need to comply with the strict rules of building regulations, which our buildings do not.

 

- No more than 50% of the area of land around the original house** should be taken up by garden buildings or other buildings .

 

-Outbuildings should not be closer to a road or public highway than the original house** itself.

 

-If your garden building does NOT meet the above criteria, e.g. if you want a garden building taller than 2.5m and situated less than 2.0m from a boundary of your property, then you would NEED to apply for planning permission.

 


 

If, however, your garden building DOES comply with the above criteria, you won't need to apply for planning permission and you can have a garden building up to 30m2 (internal size). Anything bigger than 30m2 will need to go through building regulations.

 

Special Considerations

 

Listed buildings are objects or structures that have been judged by Historic England and the Secretary of State for Culture, Media and Sport to be of national importance in terms of architectural or historic interest. These structures, once approved, feature on a dedicated register called the List of Buildings of Special Architectural or Historic Interest.

 

There are increased rules around listed buildings, so any garden building or outbuilding that is to be placed within the curtilage of a listed property will require planning permission. If you go one step further and require a structure to be built and attached to a listed property, you will need both listed building consent AND planning permission (although this is a service that Crane does not offer).

 

These restrictions should not put you off though, as we build a considerable number of garden buildings for customers with listed properties.

 

Designated Land 

 

There are also additional limitations if your property is located on designated land. Designated land is the term used to describe areas of interest such as: national parks, the Broads, World Heritage Sites, Areas of Outstanding Natural Beauty and conservation areas.

 

There are two main points to get your head around with designated land: one includes conservation areas, one does not:

 

1.Let's start with the first point (this point only refers to garden buildings that are to be placed in either national parks, World Heritage Sites, the Broads or Areas of Outstanding Natural Beauty. NOT conservation areas): the maximum area to be covered by garden buildings that are positioned more than 20m from any wall of the house is limited to 10m2. You can still have a garden building larger than 10m 2 in your garden if you wish, you would just need to obtain planning permission before you can do so.

 

2.The second point refers to designated land as a whole (so it INCLUDES conservation areas): on designated land you cannot have a garden building to the side of a property without requiring planning permission.

 

Once you have clarified these points and know that you are following the above criteria, you can refer to what we call, the 'normal planning rules'. These are the criteria that have been specified from the beginning of this article in the first.

 

Obtaining planning permission is not as difficult a process as popular myth would lead you to believe; our dedicated team are always on hand to advise and help if you should have any concerns or wish to check any information with us.

 

For further information, visit the Government Planning Portal website .

 


 


 


 


 


 


 


 

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Why Granny Annexes Are Trending in 2025 The demand for granny annexes has surged for several compelling reasons: Multi-Generational Living: Families are increasingly choosing to live closer together, providing support for elderly parents while maintaining independence and privacy for everyone. Property Value: A quality granny annexe can add 20-30% to your property's value, making it an excellent return on investment. Rental Income: Many homeowners use granny annexes as rental properties, generating steady income that can help with mortgage payments or retirement savings. Aging in Place: Rather than moving to care facilities, elderly parents can stay close to family while maintaining their independence in a purpose-built, accessible space. Home Office Evolution: Some families initially build annexes as home offices or creative studios, with the flexibility to convert them later. Planning Permission and Building Control: What You Need to Know One of the first questions homeowners ask is: "Do I need planning permission?" Permitted Development Rights: In many cases, granny annexes fall under permitted development rights, meaning you may not need full planning permission if your annexe meets specific criteria: • The annexe is within your property boundary • It doesn't exceed 50% of the land around your original house • Maximum height restrictions apply (2.5m for annexes within 2m of a boundary, 4m elsewhere) • The building is single-storey • It's used in connection with the main dwelling (not as an independent dwelling) When You Need Planning Permission: • If your property is in a conservation area or listed building • If the annexe will be used as a completely separate dwelling with its own utilities • If your site has had previous extensions that used up permitted development rights Building Control is Always Required: Even if you don't need planning permission, you must comply with building regulations. This includes: • Structural stability • Fire safety • Insulation and energy efficiency standards • Drainage and ventilation • Electrical and plumbing safety Pro Tip: Work with an experienced construction company that handles building control submissions—it will save you time, stress, and potential costly mistakes. Modern Construction Methods: SIP Panels vs Traditional Build The construction method you choose significantly impacts your annexe's energy efficiency, build time, and overall cost. SIP (Structural Insulated Panel) Construction: SIP construction has revolutionized granny annexe building. These foam-injected panels offer exceptional benefits: Advantages: • Superior Insulation: SIP panels provide significantly better thermal performance than traditional builds, reducing heating costs by up to 60% • Faster Build Time: A SIP annexe can be weathertight in days rather than weeks • Precision Engineering: Panels are manufactured to exact specifications, ensuring perfect fit and minimal waste • Airtight Construction: Dramatically reduces heat loss and improves comfort • Year-Round Comfort: Stays warm in winter, cool in summer Traditional Brick and Block Construction: Traditional methods remain popular and offer their own advantages: Advantages: • Familiarity: Many builders are experienced with traditional techniques • Aesthetic Match: Easier to match existing property appearance • Flexibility: Changes can be made more easily during construction • Perception: Some homeowners prefer the "solid" feel of brick Our Recommendation: For granny annexes, SIP construction offers the best balance of energy efficiency, build speed, and cost-effectiveness. The superior insulation is particularly important for elderly occupants who need consistent, comfortable temperatures. Real Project Example: Our Cheshunt Granny Annexe To illustrate what's possible, here's a recent project we completed in Cheshunt, Hertfordshire: Project Overview: • Modern self-contained granny annexes using SIP construction • Screw pile foundations (minimal ground disturbance) • Composite cladding with K render finish • Fully equipped with kitchenette, bathroom, and air conditioning • Full building control compliance achieved Timeline: Completed within agreed schedule Result: A warm, energy-efficient, self-contained living space that exceeded the client's expectations The client told us: "I couldn't be happier with the Granny Annex and it has far exceeded my expectations! From the initial planning stage right through to the day I got the keys Costi and his team were there." Cost Breakdown: What to Budget Granny annexe costs vary based on size, specification, and construction method, but here's a realistic UK budget guide for 2025: Basic Granny Annexe (20-30m²): • Budget Range: £40,000 - £60,000 • Includes: Basic kitchen, bathroom, living/sleeping area • Construction: Standard insulation, basic finishes Mid-Range Granny Annexe (30-40m²): • Budget Range: £60,000 - £90,000 • Includes: Full kitchen, separate bathroom, bedroom, living area • Construction: SIP panels, quality finishes, good insulation High-Specification Granny Annexe (40-50m²): • Budget Range: £90,000 - £120,000+ • Includes: Luxury fittings, underfloor heating, air conditioning • Construction: Premium SIP construction, designer finishes Additional Costs to Consider: • Professional fees (architect, structural engineer): £2,000 - £5,000 • Building control fees: £500 - £1,500 • Utility connections: £1,000 - £5,000 • Landscaping and access: £2,000 - £8,000 Design Considerations for Comfort and Accessibility A granny annexes should prioritize comfort, safety, and accessibility: Layout Essentials: • Open Plan: Maximizes space and ease of movement • Level Access: No steps between rooms or to entrances • Wide Doorways: Minimum 800mm for wheelchair access • Wet Room: Safer than traditional bathrooms, with level access shower Heating and Ventilation: • Underfloor heating provides even warmth without radiators • Mechanical ventilation with heat recovery (MVHR) ensures fresh air • Air conditioning for summer comfort (especially important for elderly) Safety Features: • Non-slip flooring throughout • Adequate lighting (especially at night) • Emergency call system linking to main house • Grab rails in bathroom • Level threshold entrances Future-Proofing: • Design for potential mobility aids • Install extra electrical sockets at accessible heights • Consider wider spaces for future wheelchair use Key Takeaways Building a granny annexes is a rewarding project that enhances your property, provides valuable living space, and supports multi-generational family life. Here's what to remember: 1. Check Planning Requirements Early: Understand permitted development rights and building control requirements before you start 2. Choose Modern Construction: SIP construction offers superior energy efficiency and faster build times 3. Budget Realistically: Factor in all costs including professional fees and utilities 4. Prioritize Accessibility: Design for current and future mobility needs 5. Work with Experienced Professionals: A specialist construction company will navigate regulations and deliver quality results With careful planning, the right construction partner, and attention to design details, your granny annexes can become a beautiful, functional space that serves your family for generations to come. With over 25 years of experience in the UK construction industry, TRJ Construction delivers quality projects across Hertfordshire and beyond. For more information about granny annexes construction or to discuss your project, contact us costi@trj-construction.co.uk or call +44 7966 800519.