Conservatory Planning Permission Rules

When you need planning permission for a conservatory, the permitted development rules that apply, and key building regulations requirements.

Most conservatories can be built under permitted development rights without planning permission, but there are important size limits and conditions to be aware of.

When You Do Not Need Planning Permission

A conservatory is treated the same as a single storey rear extension for permitted development purposes. You can build one without planning permission if:

• It is at the rear of the property (not forward of the principal elevation)
• It does not extend more than 4 metres from the rear wall (detached houses) or 3 metres (semi-detached and terraced) - or up to 8m/6m under prior approval
• Maximum eaves height: 3 metres
• Maximum overall height: 4 metres
• It covers no more than 50% of the garden area (including all other outbuildings and extensions)
• It is single storey

When You Need Planning Permission

• The conservatory exceeds the size limits above
• It is at the front or side of the property
• Your property is listed (you will also need listed building consent)
• You live in a conservation area and the conservatory is to the side
• Your property is a flat or maisonette
• An Article 4 Direction has removed permitted development rights
• Previous extensions have used up your permitted development allowance

Building Regulations

Conservatories are exempt from building regulations if all of the following apply:

• Floor area is less than 30 square metres
• The conservatory is at ground level
• It is separated from the house by external walls, doors or windows (i.e. you keep the existing external wall and doors between the house and the conservatory)
• The heating system is separate from the house's central heating, or has independent temperature controls
• The electrical installation is carried out by a Part P qualified electrician (or inspected by building control)
• The glazing complies with safety standards

If you remove the wall or doors between the house and the conservatory - making it an open-plan room rather than a separated structure - the conservatory loses its exemption and must comply with full building regulations, including thermal insulation standards.

Conservatory vs Orangery vs Extension

• Conservatory: predominantly glazed walls and roof. Exempt from building regulations if separated from the house
• Orangery: brick or rendered walls with a glazed lantern roof. Generally requires building regulations approval as it has more solid construction
• Extension: conventional construction with a solid roof. Always requires building regulations approval

The distinction matters for building regulations. If more than 50% of the wall area and 75% of the roof area is glazed, it is typically classified as a conservatory.

Typical Costs

• UPVC conservatory (3m x 3m lean-to): £8,000-£15,000
• UPVC conservatory (3m x 4m Victorian or Edwardian style): £12,000-£22,000
• Aluminium-framed conservatory: £15,000-£30,000
• Hardwood-framed conservatory: £20,000-£40,000
• Orangery: £25,000-£50,000

Costs vary significantly based on size, materials, glazing specification (double vs triple), roof type, and foundation requirements.

Considerations

• Overheating in summer - consider solar-control glazing, blinds, or opening roof vents
• Cold in winter - older-style conservatories with polycarbonate roofs are difficult to heat. Modern glass roofs with thermal coatings perform much better
• Solid roofs - increasingly popular to replace polycarbonate or old glass roofs with insulated solid roof panels, making the conservatory usable year-round
• Drainage - ensure rainwater is properly connected to a soakaway or surface water drain