Planning Portal guidance confirms that a conservatory’s exemption from Building Regulations depends on it being separated from the house by external-quality walls, doors or windows, and that any new structural opening between the conservatory and the existing house requires Building Regulations approval, even where the conservatory itself is an exempt structure.

The condition behind the exemption

A conservatory in England can be exempt from Building Regulations where it meets a specific set of conditions together: built at ground level, no more than 30 square metres in floor area, single storey, glazing and electrics that meet the relevant standards, and crucially, thermal separation from the house by external-quality walls, doors or windows, with no heating system extended into it from the house. All of these conditions apply together; the exemption is not simply about size or location, it depends on the conservatory remaining a genuinely separate space from the main dwelling.

What counts as a new structural opening

Planning Portal guidance is specific that any new structural opening between the conservatory and the existing house needs Building Regulations approval, regardless of whether the conservatory itself is exempt. Removing an external-quality door set, or widening or removing the wall that provides the thermal separation, to create a single open-plan space between house and conservatory, falls squarely within this: it is a structural change to the boundary the exemption depends on, not simply a cosmetic update.

Why this catches people out

Because the conservatory itself was built as an exempt structure, and might have needed no approval at all when it was originally installed, homeowners can reasonably assume that later changes to it are equally exempt. Removing the doors between house and conservatory is a common way to create a larger, more open living space, but it changes the legal status of the opening between the two spaces specifically, which the original exemption never covered in the first place, whatever was true of the conservatory as originally built.

What approval then involves

Once the structural opening itself requires Building Regulations approval, the work has to be assessed against the normal building control requirements that would apply to any structural opening of that kind, covering matters such as structural adequacy where a wall is altered, and how the enlarged, connected space performs thermally and in terms of condensation risk, since the conservatory is no longer functioning as a separated, independently controlled space once the connecting doors or wall are gone. The specific technical standards that then apply are confirmed through the local authority’s building control team or an approved inspector as part of the application, rather than assumed in advance.

Does this apply in Wales too

Welsh guidance sets out the same core conditions for a conservatory’s exemption, including thermal separation from the house by external-quality walls, doors or windows, and confirms in the same way that any new structural opening between the conservatory and the existing house requires Building Regulations approval. The underlying principle, that removing the separation removes the basis for exemption, holds on both sides of the England-Wales border, even though the two nations administer building regulations separately.

Checking before you remove anything

Before removing doors or a dividing wall between a conservatory and the main house, checking with the local authority’s building control department, or an approved inspector, on what will be required for that specific structural opening is the sensible step, rather than treating it as a straightforward like-for-like alteration to an already-exempt space. Carrying out this kind of work without the necessary approval can create the same problems as any other unauthorised building work, including difficulty at the point of a future sale.

FAQs

Does removing the doors between my house and conservatory need approval even if the conservatory itself was exempt?

Yes. Planning Portal guidance confirms any new structural opening between the conservatory and the existing house needs Building Regulations approval, regardless of the conservatory’s own exempt status.

What is the underlying condition my conservatory’s exemption depends on?

Thermal separation from the house by external-quality walls, doors or windows, alongside conditions on size, storeys and having no extended heating system.

Does this rule apply in Wales as well as England?

Yes. Welsh guidance sets out the same core thermal separation condition and the same requirement for approval of a new structural opening.

Who confirms what standard the enlarged, connected space then has to meet?

The local authority’s building control team or an approved inspector, as part of the Building Regulations application for the structural opening.

Bottom line

A conservatory’s Building Regulations exemption depends on it staying thermally separated from the house by external-quality doors, walls or windows, and removing that separation to create an open-plan space is treated as a new structural opening requiring Building Regulations approval, whatever the exempt status of the conservatory itself. This applies in both England and Wales. This is general information, not planning or building control advice on a specific property; the local authority’s building control team can confirm what a particular alteration will require.

Sources

This guide draws on the following primary sources, current as of 22 September 2026:

• Planning Portal, “Building regulations – Conservatories”
• GOV.WALES, “Building regulations: conservatories”

Related guides

Compare Conservatories is an independent guide. We may earn a fee from some links; this never affects what we write. This article is general information, not legal or planning advice on any specific property — always confirm requirements directly with your local planning authority.