Do I Need Building Control for a Conservatory

A conservatory can be a practical and attractive way to add living space to your home. But before you start the project, it’s important to understand whether building control approval is required. While some conservatories are exempt from building regulations, others must be inspected and signed off. The difference comes down to how the conservatory is designed, constructed, and used.

In many cases, conservatories are treated as permitted development and don't need planning permission. However, building control is a separate process focused on safety, insulation, and structural performance — and the rules are not always as simple as they seem.

When a Conservatory is Exempt from Building Control

To be exempt from building control, a conservatory must meet specific criteria. It must be built at ground level and be less than 30 square metres in floor area. It should be separated from the main house by external-quality doors, windows, or walls, and should not affect existing drainage systems.

The conservatory must also have its own independent heating system that can be controlled separately from the main house. If these conditions are met, the structure is generally considered exempt and can be built without building control approval.

This exemption applies to domestic conservatories attached to a single-family dwelling, not flats or commercial buildings.

When You Do Need Building Control for a Conservatory

If your conservatory fails to meet the exemption criteria, it will need building control approval. For example, if you remove the doors or wall between the house and the conservatory to create an open-plan space, you are no longer meeting the rules for separation. This changes the conservatory’s thermal performance and means the extension must comply with the same insulation and energy efficiency standards as the rest of the house.

If the conservatory exceeds 30 square metres, includes complex structural elements, or alters existing drainage or load-bearing walls, it will also fall under building regulations. The roof and walls will be assessed for energy performance, ventilation, and structural stability. In some cases, foundations and glazing will also be inspected.

Heating is another key issue. If the conservatory is connected to the home’s main central heating system without independent controls, it will be classed as a heated extension and must meet full thermal and energy standards. This is a common trigger for building control involvement, especially in modern designs that aim to integrate the conservatory with the rest of the home.

Importance of Compliance

Ignoring building control requirements can lead to problems down the line. If you build a conservatory that should have been inspected but wasn’t, the local authority could take enforcement action or require you to apply for retrospective approval. If the work fails to meet standards, costly alterations may be needed.

When selling your home, missing documentation can delay the process or reduce the property’s value. Buyers and solicitors often request proof that extensions, including conservatories, comply with building regulations where necessary.

Complying from the start avoids all of this. It ensures the work is legal, safe, and efficient — and protects your investment in the long term.

What Counts as a Conservatory?

Not every glazed extension qualifies as a conservatory in the eyes of building control. A true conservatory is defined by its construction — typically with at least 75% of the roof and 50% of the walls made of translucent materials such as glass or polycarbonate. If your structure has a solid roof or walls made mostly of brick, it may be classed as a standard extension, and full building regulations will apply.

Some companies market garden rooms or “sunrooms” that look similar to conservatories but don't meet the same material requirements. These usually need approval because they don't fall under the exemption rules.

The Impact of Replacing a Conservatory Roof

A common project involves replacing an existing glazed conservatory roof with a solid tiled or insulated roof to improve energy efficiency. This kind of upgrade nearly always requires building control approval. A solid roof changes the classification of the space and affects the thermal performance, weight distribution, and ventilation of the entire structure.

Building control will assess whether the existing foundations and framework can support the heavier roof and whether the new design complies with energy regulations. This includes insulation values (U-values), condensation control, and structural safety.

Integration with the Main House

One of the biggest triggers for building control is how the conservatory connects to the existing property. As soon as you remove the doors or external wall between the conservatory and the house — even partially — the conservatory becomes a full extension in regulatory terms.

That means you’ll need to meet the same standards for thermal insulation, heating efficiency, ventilation, and structural integrity as if you were building a brick-and-mortar room. It also means the glazing must meet stricter safety and energy standards, particularly if it’s near doors or floor level.

Party Walls and Boundary Considerations

If your conservatory is close to a boundary or attached to a party wall, additional rules may apply. Even if building control approval isn’t required for the conservatory itself, you might still need to follow the Party Wall Act. This is a separate legal requirement that ensures your work doesn’t affect neighbouring properties or shared walls. Failure to do so can lead to legal disputes.

Listing and Conservation Area Rules

If your property is listed or located in a conservation area, you must be extra cautious. While building control exemption may still technically apply, listed building consent or conservation approval could override it. Local authorities can apply stricter rules in these cases and require full compliance with planning and building regulations, even for modest conservatory work

Heating and Electrical Work

Even if the structure of the conservatory is exempt from building control, certain parts of the project may still need approval. Electrical installations — especially in wet areas or involving consumer units — must be carried out by a registered electrician or approved through a Competent Person Scheme. Likewise, if you’re installing underfloor heating or connecting radiators to your existing system, building control may require this to be inspected and signed off.

Final Word

Not every conservatory needs building control approval, but knowing where your project stands is crucial before building begins. The rules depend on size, structure, heating, and whether the space is fully open to the rest of the home. If you're in doubt, speak to your local building control team or an approved inspector before starting work. A little clarity up front can save you a lot of time, money, and stress later on.