Building Regulations for Conservatories: The Exemption

Building regulations cover the structural and thermal performance of all new buildings and extensions. However, conservatories have a specific exemption that has been in place for decades, recognising that a lightly constructed glazed structure attached to a house is not the same as a permanent extension.

The exemption is set out in Schedule 2 of the Building Regulations 2010 (as amended). It is conditional — all four criteria must be met simultaneously for the exemption to apply.

The Four Exemption Criteria

If all four criteria are met, no building regulations application is needed and no completion certificate is issued. This is why many older conservatories have no paperwork — the exemption was self-certified.

What Happens if the Exemption Does Not Apply?

If the conservatory does not meet all four criteria, it is treated as a standard extension and full building regulations approval is required. This means:

• Submitting a building regulations application to your local authority building control (LABC) or an approved inspector
• The structure must meet current Part L (thermal performance) requirements for walls, roof, floor and glazing
• Structural requirements under Part A apply
• Fire safety requirements under Part B may apply (e.g. if a new means of escape is affected)
• A completion certificate is issued when work is signed off

Common reasons a conservatory fails the exemption:

• A wall radiator or underfloor heating powered by the main boiler is installed
• The internal separation wall is removed to create an open-plan space
• The conservatory is larger than 30m²
• An electric underfloor heating mat is used (this is a grey area — consult building control)

The 2022 Part L Changes

The 2022 uplift to Part L (Conservation of Fuel and Power) introduced new minimum standards for the thermal performance of extensions. For conservatories that do not qualify for the building regulations exemption, the new standards require improved U-values for roofs, walls, floors and glazing compared to the previous 2013 standards.

The key change affecting conservatories:

• Roof lights and glazed roofs: maximum U-value 1.6 W/m²K (down from 2.2)
• External walls: maximum U-value 0.26 W/m²K
• Floors: maximum U-value 0.18 W/m²K

Conservatories that meet the exemption criteria are unaffected by Part L as they are exempt from building regulations entirely.

Completion Certificates and Insurance

An exempt conservatory has no completion certificate because no building regulations application was made. This is normal and should not cause problems when selling the property, provided the conservatory was genuinely built to the exempt specification.

For a non-exempt conservatory with a completion certificate, the certificate is important evidence for conveyancers and insurers. Without it, you may need to obtain an indemnity insurance policy, which typically costs £200–£500 for a single incident.

Frequently Asked Questions