A log cabin can still be permitted development on designated land, but the rules are tighter, and one popular fact — the 10 square metre limit — does not apply to conservation areas. Every conservation area, National Park, AONB (National Landscape) and World Heritage Site removes permitted development for a cabin sited to the side of the house. National Parks, the Broads, AONBs and World Heritage Sites go further and cap anything more than 20 metres from the house at 10 square metres. Conservation areas do not carry that particular cap, but they do get closer council scrutiny and are the most common home for an Article 4 direction that removes permitted development altogether.
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Quick Answer
| Designation | Extra rule that applies |
|---|---|
| National Park, the Broads, AONB/National Landscape, World Heritage Site | 10m² cap on anything more than 20m from the house, plus no siting to the side |
| Conservation area | No siting to the side, plus heightened design scrutiny — not the 10m² rule |
| Curtilage of a listed building | No permitted development at all — planning permission needed, possibly listed building consent too |
| Any of the above with an Article 4 direction | Permitted development can be removed entirely — check first |
| Away from all of these | Normal Class E outbuilding limits only (height, boundary, 50% garden rule) |
The GOV.UK householder technical guidance and the Planning Portal outbuildings guidance are the official references for the rules below.
What Counts as "Designated Land"
The GPDO calls it "article 2(3) land" — PlanWatch will just call it designated land. It covers:
- National Parks
- The Broads
- Areas of Outstanding Natural Beauty (AONBs), now branded National Landscapes
- Conservation areas
- World Heritage Sites
If your property sits inside any of these, some of the normal permitted development rights for outbuildings (Class E) are cut back. Start with our main guide if you haven't already: Do I need planning permission for a log cabin?
The 20m / 10m² Rule — and Where It Actually Applies
This is the rule most often misquoted, so it's worth being precise.
On National Parks, the Broads, AONBs (National Landscapes) and World Heritage Sites, an outbuilding is not permitted development if the total ground covered by buildings, enclosures, pools and containers more than 20 metres from any wall of the house would exceed 10 square metres.
- Within 20m of the house, this rule doesn't bite — the normal Class E limits apply instead (height, boundary distance, 50% garden rule).
- Beyond 20m, on these four designations, your cabin's footprint (added to anything else out there) must stay at or under 10m² to remain permitted development. Go bigger, and you need a planning application.
Conservation areas are not on this list. There is no automatic 10m²/20m cap for a log cabin in a conservation area. Don't let a seller or forum tell you otherwise — see the next section for what conservation areas actually restrict.
Conservation Areas: What Really Changes
Conservation areas are designated land, so they are not rule-free — but the specific restriction is different from the 10m² cap above.
- No siting to the side of the house. This is the rule that does apply in conservation areas (see below) — it removes permitted development for anything positioned between a side wall of the house and the boundary of the curtilage.
- Heightened scrutiny. Councils have a statutory duty to preserve or enhance the character and appearance of a conservation area. Even where a cabin is technically permitted development, expect closer attention to materials, visibility and impact if you ever need to apply, and less tolerance for anything borderline.
- Article 4 directions are common here. Conservation areas are the most frequent location for a council to have removed permitted development rights altogether — see below.
For the fuller picture on what a conservation area designation does and doesn't restrict, read Conservation areas and planning.
No Permitted Development to the Side — On All Designated Land
Separately from the 10m² rule, all designated land — National Parks, the Broads, AONBs, conservation areas and World Heritage Sites alike — removes permitted development for any outbuilding sited between a side wall of the house and the boundary of the curtilage.
In practice: on designated land, a cabin down the side return or side garden is not permitted development, whichever of the five designations applies. It needs to go behind the house, and even then a planning application may be required if it's beyond 20m and over 10m² on the four landscape designations above.
The baseline Class E limits — height, single storey, behind the front of the house, the 50% garden rule — still apply everywhere on top of these extra restrictions. Full detail: How big can a log cabin be without planning permission?
AONB → "National Landscape": Name Only
Areas of Outstanding Natural Beauty were re-branded National Landscapes on 22 November 2023. This is a name change, not a legal change — the statutory designation is still "Area of Outstanding Natural Beauty" under the relevant legislation and the GPDO, and the permitted development restrictions described above are unchanged. If your council or estate agent calls it a National Landscape, treat it exactly as an AONB for planning purposes.
Listed Buildings and Curtilage Listing
Permitted development for outbuildings is removed entirely within the curtilage of a listed building — a log cabin there needs planning permission regardless of size or siting.
It can go further than the main house itself:
- Curtilage listing. A structure can be treated as part of a listed building's protection if it is fixed to the building, or if it stands within the curtilage and has formed part of the land since before 1 July 1948. Whether a particular outbuilding or site counts is a question of fact and degree, ultimately decided by the council or the courts.
- Listed building consent. Building a new cabin in the curtilage of a listed building will generally need planning permission, and works that alter, attach to, or affect the setting of the listed building may also need listed building consent on top. Carrying out such works without consent can be a criminal offence.
See our dedicated guide for the full detail: Planning permission for listed buildings.
Article 4 Directions: Always Check Before You Order
A council can issue an Article 4 direction removing specific permitted development rights in a defined area — most commonly in a conservation area, but not only there. Where one is in force, work that would normally be permitted development needs a full planning application instead, even if it would otherwise meet every Class E limit.
Article 4 directions are property- and street-specific: a cabin that's fine two doors down can need permission at your address. Always check with the council's planning department, or search its conservation area and Article 4 pages, before ordering a cabin for a property on any of the designations above. For the wider permitted development picture, see Permitted development rights explained.
Practical Checks Before You Buy
- Confirm which designation, if any, applies — National Park, the Broads, AONB/National Landscape, conservation area, or World Heritage Site. Council mapping tools usually show this.
- If it's a National Park, the Broads, an AONB or a World Heritage Site, measure the distance from every wall of the house — over 20m, keep the footprint to 10m² or less.
- On any designated land, keep the cabin behind the house, not to the side.
- Check whether the property is listed, or sits in the curtilage of a listed building.
- Ask the council whether an Article 4 direction applies to the property.
- Still check the standard limits — height near the boundary, single storey, behind the front elevation, the 50% garden rule.
- For anything borderline or expensive, consider a lawful development certificate before you build.
Area Examples
Designated-land scrutiny is highest where landscape character is part of the council's core policy — for example Cornwall, the Lake District and the South Downs, where National Park and AONB boundaries cover large parts of the area and cabins facing side gardens or exceeding the 20m/10m² rule are a recurring refusal reason. Elsewhere, search your own council to see how conservation area cases and Article 4 directions have been applied locally.
Frequently Asked Questions
Does the 10 square metre rule apply to log cabins in conservation areas?
No. The 10 square metre / 20 metre rule (Class E, condition E.2) applies only in National Parks, the Broads, Areas of Outstanding Natural Beauty and World Heritage Sites. Conservation areas are not in that list. Conservation areas are instead caught by the no-side-elevation rule and by heightened design scrutiny.
Can I put a log cabin to the side of my house in a conservation area?
No, not as permitted development. On all designated land, including conservation areas, permitted development does not cover a building sited between a side wall of the house and the boundary of the curtilage. A cabin to the side needs a planning application.
What is the 20 metre / 10 square metre rule?
In National Parks, the Broads, AONBs (National Landscapes) and World Heritage Sites, an outbuilding more than 20 metres from any wall of the house is limited to a combined footprint of 10 square metres to remain permitted development. Closer than 20 metres, the normal outbuilding limits apply instead.
Is an AONB the same as a National Landscape?
Yes. Areas of Outstanding Natural Beauty were re-branded National Landscapes on 22 November 2023. It is a name change only — the legal designation and the planning rules are unchanged.
Can I build a log cabin if my house is listed?
Permitted development for outbuildings is removed within the curtilage of a listed building, so you will need planning permission. If the cabin site or an existing structure is curtilage-listed, or the works affect the listed building's setting, you may also need listed building consent.
What is an Article 4 direction and how do I check for one?
An Article 4 direction is a notice a council can issue to remove specific permitted development rights in a defined area, often a conservation area. Where one applies, work that would normally be permitted development needs a full planning application instead. Ask your council's planning department or check its conservation area pages before ordering a cabin.
Check Your Area
Before you order, see how your council has actually treated recent garden cabins and outbuildings on designated land — approvals, refusals, and the reasons why.
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Further Reading
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Search Your Postcode FreeDisclaimer: PlanWatch provides general information about UK planning processes. This content is not legal advice. Planning law is complex and varies by local authority. Consult a qualified planning consultant or solicitor for advice specific to your situation.
