Conservatories can be exempt from building regulations — but only if they meet specific criteria. Here’s exactly when the exemption applies, and what happens when it doesn’t.
A conservatory is exempt from building regulations if it is at ground level, under 30m², separated from the house by external-standard walls/doors/windows, and does not have the main heating extended into it. If any condition fails, building regulations apply.
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.
| Criterion | Detail |
|---|---|
| 1. At ground level | The conservatory must be at ground floor level only — not elevated or on a first floor |
| 2. Under 30m² | The floor area of the conservatory must be less than 30 square metres |
| 3. Separated from the house | The walls, windows and doors separating the conservatory from the house must be of the same standard as the external envelope — i.e. insulated, draught-proof, double-glazed |
| 4. Heating not extended | The main central heating system must not be extended into the conservatory — it cannot be on the same circuit as the house heating |
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.
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:
Common reasons a conservatory fails the exemption:
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:
Conservatories that meet the exemption criteria are unaffected by Part L as they are exempt from building regulations entirely.
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.
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