Permitted development in a National Park: what still applies
National Parks are article 2(3) land, which removes several householder rights outright and tightens others. A class by class look at what is left.
Permitted development in a National Park is narrower than most owners expect, and the reason is a single definition. National Parks are article 2(3) land under the General Permitted Development Order 2015, which strips out several householder rights entirely and tightens others.
The practical effect is that the works most people assume are automatic, a side extension, a dormer, cladding the elevation, a large garden building at the bottom of the plot, are either removed or cut back. What remains is still useful, and knowing exactly what remains is what stops a wasted design.
What article 2(3) land means here
Article 2(3) land covers National Parks, the Broads, National Landscapes, conservation areas and World Heritage Sites. The designation does not remove permitted development wholesale. It applies a set of exclusions and reduced limits within individual classes.
In a National Park there is a second layer. The National Park authority is the local planning authority for planning purposes, so the prior approval applications, the certificates and the enforcement all sit with that authority rather than the district council you pay council tax to.
Those two things are independent. The article 2(3) restrictions would apply to a conservation area inside a district council area in exactly the same way, and being inside a National Park does not add further householder restrictions beyond the article 2(3) list unless an Article 4 direction has been made.
Householder rights that are cut back
Under Class A of Part 1, the changes are specific and worth memorising if you work in a Park regularly.
| Work | Position on article 2(3) land |
|---|---|
| Side extension | Not permitted |
| Rear extension of more than one storey | Not permitted |
| Cladding the exterior with stone, timber, tiles or render | Not permitted |
| Larger single-storey rear extension under prior approval | Not available |
| Roof extension or dormer under Class B | Not permitted |
The cladding exclusion surprises people most often, because rendering a tired 1970s elevation feels like maintenance rather than development. On article 2(3) land it needs planning permission.
Roof alterations under Class C, which cover rooflights and other alterations that do not project much beyond the plane of the roof slope, are not excluded. That is why conservation rooflights appear so often on Park houses while dormers do not.
Outbuildings and the twenty metre rule
Class E, the outbuildings class, keeps working in a National Park with one important limit. Where a building sits more than 20 metres from any wall of the house, the total ground area covered by such buildings is capped at 10 square metres.
That is a small shed, not a garden room. Anything larger at the far end of a long garden needs permission, while the same structure placed within 20 metres of the house may well be permitted subject to the other Class E limits on height, eaves and position relative to the principal elevation.
Measure the 20 metres from the wall, not from the boundary or the patio, and measure to the nearest part of the proposed building. On sloping ground, check the height limits carefully too, because a building that reads as single storey from the house can exceed the eaves limit on the downhill side. The wider test of whether the building is incidental to the enjoyment of the house still applies, as set out in the note on when a garden office stops being incidental.
Classes removed altogether
Several whole classes do not apply on article 2(3) land, and these matter more to owners and small developers than the householder detail.
Class Q, the agricultural building to dwelling conversion, is not available. That single exclusion shapes rural development in Parks more than any other provision, because a barn that would convert under prior approval two miles outside the boundary needs a full application inside it, assessed against countryside and landscape policy. The structural works test in a Class Q conversion simply never arises.
The upward extension classes in Part 20, which allow additional storeys on houses and other buildings, exclude article 2(3) land as well. So the Class AA upward extension route is closed in a Park.
Telecommunications development under Part 16 is tighter, and some equipment that is permitted elsewhere requires prior approval or full permission on designated land.
Agricultural classes in a Park
Agricultural permitted development survives in National Parks but with extra procedure. Part 6 rights on larger holdings continue to apply, and the prior notification route on holdings of five hectares remains available, but designated land attracts a wider prior approval test covering siting, design and external appearance.
Expect the authority to engage properly with that test rather than waving it through. In a Park, the design and external appearance of a farm building is a genuine landscape question, and authorities regularly require darker cladding, a lower roof profile or a different siting within the field.
Plan the 28-day determination period into the programme, and do not start work in reliance on the expiry of that period unless you are certain nothing has been served.
The Part 6 conditions also survive designation. A building erected under agricultural permitted development has to be used for agriculture, and a change to a different use within the protected period brings its own consequences. Owners who put up a Part 6 building with a diversification scheme in mind should take advice on that sequence first.
Solar, heat pumps and the elevation question
Microgeneration rights under Part 14 continue in a Park with additional limits, most of which turn on visibility from a highway. Equipment on a wall fronting a highway is commonly excluded on article 2(3) land, and standalone installations have their own restrictions.
Air source heat pumps are the live issue on most retrofit projects. The class has conditions on siting, noise and proximity to boundaries, and the designated land restrictions bite on the most convenient position, which is usually the elevation facing the lane.
Work the position out before ordering equipment. Relocating a unit to a rear courtyard at design stage costs nothing, and an installation in the wrong place is an enforcement risk rather than a technicality.
Checking the boundary before you rely on anything
National Park boundaries follow historic lines rather than roads, and properties on the edge are frequently misidentified by their owners and occasionally by their agents.
Check the designation on the published spatial data rather than on a general map, and check for a conservation area at the same time, because many Park villages carry both designations and the restrictions stack. Then check whether an Article 4 direction removes anything further, since Parks use them to control matters such as boundary treatments and agricultural building colour.
Where money depends on the answer, apply for a lawful development certificate. It is the only formal way to confirm that works are lawful, it gives you a document to hand to a buyer or a lender, and a refusal tells you the position before you have built something.
A planning statement setting out the landscape context and the design response is what turns a refused permitted development assumption into a granted application, and in a Park that context does most of the persuading.
This is general guidance, not legal advice. Permitted development rights change, designations vary and the position on any particular property should be confirmed with the National Park authority or a qualified professional before you rely on it.
PlanScope provides AI-assisted draft reports for planning applications. Reports should be reviewed before submission. We do not guarantee planning approval.
Frequently asked questions
Can I build a side extension under permitted development in a National Park?
No. Side extensions are excluded on article 2(3) land, which includes National Parks, National Landscapes, conservation areas, the Broads and World Heritage Sites. So is a rear extension of more than one storey. A side extension in a Park therefore needs a householder planning application assessed against local design and landscape policy.
Are dormer windows permitted development in a National Park?
No. Class B, which covers roof extensions including dormers, does not apply on article 2(3) land. Class C alterations such as conservation rooflights that sit close to the plane of the roof slope are still available, which is why rooflights are so common on Park houses and dormers are not.
How big can a garden building be in a National Park?
Class E still applies, but where a building sits more than 20 metres from any wall of the house, the total ground area covered by such buildings is capped at 10 square metres. Closer to the house, the usual Class E limits on height, eaves and position apply instead. Measure from the wall, not the boundary.
Does Class Q barn conversion work inside a National Park?
No. Class Q is not available on article 2(3) land, so a barn that would convert under prior approval outside the boundary needs a full planning application inside it. That application is assessed against countryside, landscape and heritage policy, which is a very different test from the prior approval matters.
Who decides applications inside a National Park?
The National Park authority is the local planning authority, so prior approvals, applications, certificates and enforcement all sit with it rather than the district council. That is separate from the article 2(3) restrictions, which would apply in the same way to a conservation area inside an ordinary district council area.
Sources and further reading
This article is general guidance about the planning system in England and, where stated, the rest of the UK. It is not legal or professional advice. Check your local planning authority’s validation requirements and take professional advice for your specific site.