Conservatories Planning Permission – Your Ultimate Guide to the Regulations for 2021

Knowing whether or not you need planning permission for a new Conservatory, Orangery or single-storey extension for your home is vitally important to fully understand how to build your perfect conservatory or extension. Here are a few quick rules to keep in mind:

Planning Permission

What you CAN build WITHOUT planning permission:

  • A conservatory or extension less than 30 square metres in floor area and built at ground level
  • 50% of the wall and 75% of the roof should be glazed or comprised of a translucent material.
  • The conservatory must be separated from the house by external quality door(s).
  • Any glazing and fixed electrical installations must comply with building regulations.
Planning Permission

What you CANNOT build WITHOUT planning permission:

  • Anything built above or below ground level.
  • Any structure larger than 30 square metres.
  • Additions to a listed building, buildings in conservation areas, or structures under an Article 4 directive.

This guide has been written with supported information from the Planning Portal and We’ve researched the complicated information and put into headings so you can find what you want to know quickly.

Conservatories Planning Permission Summary

Conservatories and single-story extensions are both classified as permitted developments. This gives homeowners development rights to build small extensions and conservatories without specific planning permissions. We’ve summarised the conservatory planning rules already, but here is a quick recap:

  • A small home extension or new conservatory less than 30m2 does not require conservatory planning permission.
  • Permitted development rights allow for adding a conservatory where 50% of the wall and 75% of the roof are glazed or translucent.
  • You do not require conservatory planning permission when the conservatory door is of external quality.
  • If you are building above or below ground level, you will need permission for a conservatory.
  • You cannot build a new conservatory larger than 30m2 without a successful planning application.

Does a conservatory count as an extension?

Although a conservatory and a single-storey extension fall under the same permitted build rules, the two types of build have some key features which differentiate them as very different extensions. A conservatory is comprised of glass walls and roof structure, available in various different styles and options for glazing. It is usually built on dwarf walls. Building regulations are required before work can commence.

A house extension is also a structure featuring glass walls and roof, sometimes built on dwarf walls, but usually built with pillars which provide structural integrity which create a more sturdy building than a conservatory.

Choosing between a the two different extensions can be slightly bewildering. However, knowing the clear differences between a conservatory and an extension can help you to choose the perfect one for your home.

Do you need planning permission to build a conservatory in the UK?

In the majority of cases planning permission will not be required for your conservatory under the present (2019) legislation, unless you want to build a conservatory on a house which has already been extended. If your house is a ‘new build’ you must check that the developers have not placed restrictions that prevent certain builds being added.

Most conservatories can be built without planning permission that previously would have required it. In order to remain exempt, the following rules must be adhered too:

  • Are less than 30 square metres in floor area.
    Are built at ground level
  • 50% of the wall and 75% of the roof should be glazed or comprise of a translucent material.
  • The conservatory must be separated from the house by external quality door(s).
  • Any glazing and fixed electrical installations must comply with the applicable building regulations.

What happens if you build a conservatory without planning permission?

A lot of people believe that they can build a conservatory and get retrospective planning permission later down the line, however, this isn’t always the case and this could end up being very expensive for you. Always check to see if planning permission is required before starting a home improvement project.

Always check if your proposed conservatory build meets the permitted build requirements applicable to your home, most houses have permitted development rights, flats and maisonettes would require planning permission.

Authorities can force you to demolish a conservatory built without permitted development rights.

How big can you have a conservatory without planning permission?

There are a few variables that affect the size of your proposed conservatory, the size of the property that you’re extending is a major factor. In order to build without planning permission, a conservatory must not exceed 50% of the area around the original property, this includes any sheds or outbuildings.

Restrictions also apply to the projection from the rear and the side of the house which should be noted in order to avoid planning permission:

A conservatory may project from the rear wall of the ‘original house’ by up to eight metres for a detached house, semi-detached houses are limited to six meters.
If the build exceeds four metres the local planning authority must be informed and the neighbour consultation scheme will be applicable. These are the rules that became permanent in May 2019.

A conservatory at the rear of the property can’t exceed four metres in height, if it’s within two metres of a boundary, the height restriction is three metres or less.

A conservatory on the side of the property can not exceed 50% of the size of the original house.

Building regulations will also apply to a conservatory that has more than 30 square metres of floor area.

What can I build without planning permission?

You can build storey-height additions to the rear and sides of your property under permitted development (PD) rights. As a rule of thumb, the limit for extensions to the rear of the original house is 4m for detached homes, and 3m for semi & terraced homes.


PD allows for the building of glazed rooms which are treated as single-storey extensions – the main difference being that the requirement for materials used in the home improvement does not need to match those of the original house. To qualify as a PD, your conservatory must attach to the original dwelling and not a previous extension.

Two-Storey Extensions

Two-storey additions to the rear of the property are PD if the do not project more than 3m and are situated less than 7m from the rear boundary.

If the side elevation of the extension is situated within 2m of the flank boundary, the eaves can not exceed 3m in height.

Garden Rooms

It is permitted to erect single-storey structures such as outbuildings, sheds, summerhouses, & garages – as long as the intended use is incidental to that of the main dwelling.

The building must be behind the principal elevation of the house, and you cannot cover more than 50% of the garden with such structures. Height limits also apply.

It is worth noting that there are no PD rights for the erection of outbuildings in the grounds of listed properties. The PD rules for properties in areas of natural beauty such as conservation areas must not exceed 10m2 if they are further than 20m from the house, other restrictions apply, always check on the website before starting any projects on your home.

Can I put a conservatory on the side of my house?

You can build a conservatory or single-storey extension to the side of your property under PD rules – The construction must not cover over half the garden area. The roof ridge or highest point should not be higher than the eaves of a property’s roof.

Extensions to the side of the house must not extend beyond half the width of the house. A conservatory on the side of the property can be installed under PD rules – It should not exceed 50% of the size of the original house.

Do I need planning permission for a conservatory on the side of my house?

Planning permission to install a conservatory on the side of your house is not required as long as you follow the PD-Rules that state the following:

To build a conservatory to the side of your home without the need for planning permission, the construction must not be bigger than 50% of the area around the original house -This includes any sheds, garages and outbuildings on the grounds.
Building regulations apply to a conservatory that has more than 30 square metres of floor area, separate from planning permission.

Do I need planning permission to replace a conservatory?

In most cases, planning permission is not necessary when replacing a conservatory because permission may have already been obtained for the original build or adding one to your home falls under the ‘permitted development’ rules as long as the conditions are met.

Homeowners often confuse Planning Permission and Building Regulations, they are separate requirements of your Local Authority. Put simply, Planning Permission covers the aesthetics of a new build or extension which should match the surrounding homes in the area, Building Regulations, however, cover areas of construction such as thermal efficiency and structural integrity & health & safety.

Other regulations deal with ventilation, for instance, all new double-glazed windows must have integrated trickle vents – this is different for replacement windows where the rules state that ventilation can be the same or better, but not worse.

Do you need planning permission to convert a conservatory into a room?

If you’re looking to replace your conservatory’s existing roof to create a ‘real room’ then you may be wondering whether you need to apply for planning permission. The rules used to state that a conservatory had to have at least 75% the roof made up of a translucent material such as polycarbonate or glass in order for them to be exempt from planning permission, however, changes to building regulations in 2019 mean that planning permission for a solid roof is not required.

When planning your conservatory, it is always best to check the Planning Portal website make sure you fully understand all of the conditions that your conservatory must comply with in order to be a permitted development.

How close can a conservatory be to a boundary?

As long as the conservatory is no more than three metres high, it can go to the edge of the boundary at the side and the back of the property – It must not cover more than 50% of the area around the house to fall under PD. However just because you can, doesn’t mean that you should, here’s why:

  • Privacy:
    Placing a conservatory close to a boundary not only looks bad aesthetically but with a neighbour adjacent sound and privacy is also an issue. Glass panels are not as acoustically efficient as an insulated cavity wall.
    If you and a neighbour both have conservatories up against the boundary, not only will you both be able to hear each other you will be able to see right into each other’s rooms as well. This can be mitigated with obscured glass on/or conservatory blinds.
  • Visibility:
    Building a conservatory can be expensive, consider the view from your conservatory if you place it right next to the boundary. Your view will be a block wall, fence, hedge or neighbours conservatory.
  • Maintenance:
    Ensure to leave a minimum gap of 300mm between the boundary, this will allow access to clean the glass, maintain the frames and clean the gutters.

What are the building regulations for a conservatory?

Building regulations usually apply if you want to build an extension on your home, conservatories, however, are normally exempt when they meet the following conditions:

  • They are built at ground level and are less than 30 square metres in floor area.
  • At least half of the new wall and three-quarters of the roof is glazed or made up of a translucent material.
  • The conservatory is separated from the house by external quality door(s).
  • Glazing and any fixed electrical installations comply with the applicable building regulations requirements.

It is advised not to construct a conservatory where it can restrict ladder access to windows serving rooms in roof or loft conversions, especially if the windows are fire escapes. Structural openings created between the conservatory and the house will require building regulations approval, this is still applicable even if the conservatory is exempt.

Most conservatory refurbishment projects are exempt from building regulations and must have a significant (this is open to interpretation) proportion of the roof and walls made up of a translucent material to be considered exempt. The footprint of the existing build must not be extended, however, alterations would come under PD as long as the criteria are met if in doubt contact your local authority for help and advice.

Planning Permission Summary:

Not all property extensions or home improvements require planning permission, as long as permitted development rules are followed. To avoid requiring an application for planning permission, adhere to the following limits and conditions:

  1. No more than 50% of the area around the original house” can be covered by additions or other buildings.
  2. No extension forward of the principal elevation or side elevation fronting a highway.
  3. No extension to be higher than the highest part of the roof.
  4. Maximum depth of a single-storey rear extension of three metres for an attached house and four metres for a detached house.
  5. Maximum height of a single-storey rear extension of four metres.
  6. Maximum depth of a rear extension of more than one storey of three metres including ground floor.
  7. Maximum eaves height of an extension within two metres of the boundary of three metres.
  8. Maximum eaves and ridge height of extension no higher than the existing house.
  9. Side extensions to be single-storey with a maximum height of four metres and width no more than half that of the original house.
  10. Roof pitch of extensions higher than one storey to match existing house.
  11. No balconies or raised platforms.
  12. On designated land no permitted development for rear extensions of more than one storey; no cladding of the exterior; no side extensions. Designated land includes national parks, conservation areas and areas of outstanding natural beauty.
  13. Where work is proposed to a listed building, listed building consent may be required.
  14. The term “original house” means the house as it was first built or as it stood on 1 July 1948 (if it was built before that date). Although you may not have built an extension to the house, a previous owner may have done so.