How Big Can You Build an Orangery Without Planning Permission in the UK?

Most people think adding an orangery to their home is a big, complicated project full of permits and delays. But here’s the truth: in many cases, you can build a decent-sized orangery without ever needing to apply for planning permission. The key? Staying within the rules. If you know the limits, you can add a bright, airy space that feels like an extension of your garden-without the paperwork.

What’s the maximum size for an orangery without planning permission?

In the UK, the rules for building an orangery without planning permission fall under Permitted Development Rights. These rules let you extend your home without formal approval, as long as you stick to specific limits. For an orangery, the biggest factor is size.

You can build an orangery up to 30 square metres in floor area without planning permission-provided it’s single-storey and meets other conditions. That’s roughly the size of a small double garage or a large living room. It’s enough space for a seating area, a dining table for six, and plenty of room to move around.

But here’s where people get tripped up: the 30 square metres isn’t just about the floor plan. The orangery must also be built at ground level and be attached to your house. If you’re building it as a standalone structure, even if it’s small, you’ll likely need permission.

Height and location matter more than you think

Size isn’t the only rule. Height restrictions are just as important. The maximum eaves height (the lower edge of the roof where it meets the wall) must be no higher than 3 metres. If the orangery is within 2 metres of your property boundary, the total height-including the roof-can’t exceed 2.5 metres.

That’s why many people choose a gently sloping roof instead of a flat one. A low-pitch roof keeps the height down while still letting in light. If you’re building near a neighbour’s fence, you might need to lower the ceiling or use a lean-to design. I’ve seen too many homeowners regret pushing the height limit-only to get a notice from the council to tear it down.

Location matters too. If your home is in a conservation area, a National Park, or an Area of Outstanding Natural Beauty, the rules tighten. Even if your orangery is under 30 square metres, you’ll probably need permission. Same goes if your house is listed. In those cases, even a small glass extension can be flagged.

How close can you build to the boundary?

You can build an orangery right up to your property line-but only if it’s under 2.5 metres tall. If it’s taller than that, you need to leave at least a 2-metre gap from any boundary. That means if you want a 3-metre-high orangery, it has to sit back from your fence or hedge.

Some people try to build right to the edge to save space. But that’s risky. If your neighbour complains-maybe because it blocks their light or view-the council can still force you to make changes, even if you’re technically under the size limit. It’s better to leave a little breathing room. A 1-metre setback from the boundary gives you legal wiggle room and keeps things friendly with your neighbours.

What materials and design choices affect permission?

The materials you use can make a difference. If your orangery looks too much like a new room-brick walls, solid roof, full glazing-it might be seen as a structural extension. That’s when councils start asking questions.

The trick is to make it feel like a garden feature, not a home addition. Use a lightweight frame, glass panels, and a roof with a small pitch. Avoid solid tiled roofs unless they’re less than 2.5 metres high. Many successful orangery designs use polycarbonate roofing-it’s cheaper, lighter, and doesn’t trigger the same rules as a traditional roof.

Also, don’t add a bathroom or kitchen inside. If you install plumbing or a fixed heating system that’s permanently connected to your home’s utilities, it’s no longer just a conservatory or orangery-it’s a habitable extension. That’s when you definitely need planning permission.

What’s the difference between an orangery and a conservatory?

People use the terms interchangeably, but councils don’t. A conservatory is mostly glass-with at least 75% of the roof and 50% of the walls made of transparent material. An orangery has more solid structure: brick or timber pillars, a flat or low-pitched roof with a glass lantern, and less overall glazing.

That’s important because the rules for conservatories are more forgiving. If your structure leans more toward an orangery, you still qualify for permitted development as long as you stay under 30 square metres and under the height limits. But if your design is half-way between the two, the council might classify it as an extension-and then the rules change.

Tip: Stick to a design with no more than 50% solid walls. Use glass for the rest. Keep the roof under 3 metres. That’s the sweet spot.

What if you go over the limit?

If your orangery is bigger than 30 square metres, taller than 3 metres, or built too close to a boundary, you’re outside permitted development. That doesn’t mean you can’t build it. It just means you need to apply for planning permission.

The application process in the UK usually takes 8 weeks. You’ll need to submit plans, a site map, and sometimes a design statement. Fees range from £200 to £400, depending on your local council. But here’s the catch: approval isn’t guaranteed. Neighbours can object. The council can deny it if they think it affects the character of the area.

Many people choose to scale back instead. I’ve worked with homeowners who wanted a 40-square-metre orangery. We redesigned it as two smaller structures: a 25-square-metre orangery attached to the house, and a 10-square-metre garden room 3 metres away. Both were permitted development. They got the space they needed, without the stress.

Checklist: Can you build without permission?

• Is the orangery under 30 square metres in floor area?
• Is it single-storey and attached to your house?
• Is the eaves height no higher than 3 metres?
• If it’s within 2 metres of a boundary, is the total height under 2.5 metres?
• Is it made mostly of glass, with less than 50% solid walls?
• Is there no kitchen, bathroom, or permanent heating system inside?
• Is your home not in a conservation area, National Park, or listed building?

If you answered yes to all of these, you’re likely fine. But here’s the final step: call your local council’s planning department. Ask them to confirm in writing that your plans fall under permitted development. Get it on paper. It takes 10 minutes over the phone-and it saves you from a costly mistake later.

Real example: A 28-square-metre orangery in Brighton

A client in Hove recently built a 28-square-metre orangery with a 2.8-metre eaves height and a 1.5-metre setback from the rear fence. The roof was a low-pitch polycarbonate with a glass lantern. No plumbing. No fixed heating-just a portable heater they moved out in summer.

The council never asked for permission. They didn’t get a single complaint. The space is now used as a reading nook and lunch spot. It cost under £18,000 and added value to the home.

That’s the goal: build smart, stay within limits, and enjoy the light without the bureaucracy.

What if your neighbour objects?

Even if your orangery is perfectly legal, a neighbour can still complain. Councils don’t act on complaints automatically-but they will investigate if someone raises a concern about loss of light, privacy, or overshadowing.

If that happens, you’ll need to prove you followed the rules. That’s why keeping your plans, measurements, and council confirmation is critical. If you didn’t get written confirmation, you’re at risk. Many people assume they’re fine because they’re under the size limit-but if the council says your structure is too dominant or blocks light, they can still require changes.

Best practice? Talk to your neighbour before you start. Show them your plans. Ask if they have concerns. Most people just want to feel heard. A quick chat can prevent a formal complaint.

Next steps: How to proceed

1. Measure your proposed orangery area. Don’t guess-use a tape measure.
2. Check your property’s location: is it in a conservation area? Listed? Near a boundary?
3. Sketch a simple plan showing height, materials, and distance to boundaries.
4. Call your local council planning office. Ask: "Will a 28-square-metre orangery with a 2.8-metre eaves height and 1-metre setback need planning permission?"
5. Get their answer in writing or email.
6. Build it. Enjoy it.

You don’t need a degree in architecture or a lawyer to build an orangery. You just need to know the rules. And now you do.