An orangery is a substantial glazed extension, typically with a solid roof section and masonry or brick base walls up to window height, that creates a more permanent-feeling room than a conservatory while still maximising natural light. For planning purposes, it is treated as an extension to the dwellinghouse, and the same permitted development rules that apply to extensions determine whether planning permission is required.

Orangeries and the Extension Permitted Development Rules

Because an orangery has a largely solid roof rather than the predominantly translucent roof that defines a conservatory, it does not meet the conditions for the conservatory permitted development exemption. It is assessed simply as an extension, and the standard permitted development limits for extensions apply.

A single-storey rear orangery on a detached house is permitted development if it does not extend more than eight metres beyond the original rear wall of the house, does not exceed four metres in eaves height or four metres in total height, does not extend forward of the principal elevation, does not cover more than half the curtilage of the original house when combined with all other extensions and outbuildings, and uses materials that are similar in appearance to those of the existing house where they form an exterior wall.

For semi-detached and terraced houses, the depth limit is six metres. For extensions between three and eight metres on detached houses, or between three and six metres on other houses, the prior approval procedure applies, requiring notification to the local planning authority and a 42-day period during which neighbours can raise objections.

When Planning Permission Is Required

An orangery requires planning permission if it exceeds the permitted development limits described above, if it is a side extension, if the property is a flat or maisonette, if it is in a conservation area and the permitted development rights for cladding apply, or if the property is listed. In conservation areas, the materials restriction means that extensive glazing on an orangery facing a highway could require planning permission even if the size is within limits.

Building Regulations

Unlike a conservatory that meets the exemption conditions, an orangery almost always requires Building Regulations approval because its solid roof section is treated as a roof of an extension. This means the thermal performance of the roof must meet current standards, structural calculations are required, and the connection to the main house must be properly detailed. An orangery also typically includes electrical installations and heating, which require compliance with the relevant Building Regulations parts.

Summary

An orangery is treated as an extension for planning purposes and must comply with the standard permitted development rules for extensions rather than the conservatory exemption. Many rear single-storey orangeries fall within permitted development, but size limits, the prior approval procedure for deeper extensions, and restrictions in designated areas and listed buildings all need to be checked before proceeding. Building Regulations approval is required for virtually all orangery installations. Confirming both requirements before starting the design process avoids delays and complications during construction.