In Wales a conservatory is normally exempt from building regulations when it is built at ground level with less than 30 square metres of internal floor area, is thermally separated from the house by external quality walls, doors or windows, has no fixed heating appliance or extension of the house heating system, and has glazing and fixed electrics that comply with the regulations; a new structural opening into the house still needs approval.

The Welsh Government summary

Welsh Government guidance says building regulations will generally apply to an extension to a home, but that conservatories are normally exempt when four conditions are met. The conservatory is built at ground level and is less than 30 square metres in internal floor area; it is thermally separated from the house by external quality walls, doors or windows; there is no fixed heating appliance, or the building’s heating system is not extended into the conservatory; and the glazing and any fixed electrical installations comply with the applicable building regulations requirements. The word “normally” matters, because a project that misses any of these points is treated as an ordinary extension. The rules in England, Scotland and Northern Ireland differ; see our guides to the England exemption, Scottish building warrant exemptions and Northern Ireland Class 8.

What the regulations themselves say

Class 7 of Schedule 2 to the Building Regulations 2010, which is marked as applying to England and Wales, covers the extension of a building by the addition at ground level of a conservatory, porch, covered yard or covered way, or a carport open on at least two sides, where the floor area of the extension does not exceed 30 square metres. For a conservatory or porch that is wholly or partly glazed, the glazing must satisfy the requirements of Part N of Schedule 1, the wording that applies in Wales. The Welsh Government’s glazing guidance refers to Approved Document N for safety glazing. The Welsh Government summary adds the thermal separation and heating conditions, which relate to the energy efficiency requirements.

Glazing and safety glass

The Welsh Government’s guidance on doors and windows says safety glazing should be provided to glass in a critical area, and gives a general list: any glazed area within a window below 800mm from floor level, any glazed area within a window that is 300mm or less from a door and up to 1500mm from floor level, and within any glazed door up to 1500mm from floor level. It refers to diagram 1 in Approved Document N for more information. It also says building regulations have applied to all replacement glazing since 1 April 2002, that an external window or door is a “controlled fitting”, and that a competent person scheme installer can carry out compliant work without involving local authority building control and issue a certificate. Our guide to conservatory glazing covers the technical terms.

Electrics

The Welsh Government’s electrics guidance says electrical work in a home or garden in England and Wales must follow the Building Regulations, either by using an installer registered with a competent person scheme or by seeking approval from a building control body. It says notification is not needed for repairs, replacements and maintenance, or for extra power points and lighting points and other alterations to existing circuits, except in a kitchen, a bathroom or outdoors. The Regulations set overall criteria, Approved Document P gives practical guidance, and electrical work should follow BS 7671. The guidance notes that the Building Regulations do not restrict who may carry out electrical installation work but that anyone doing it needs to know what is required. For the England position, see our guide to Part P in England.

The structural opening and loft escape warnings

Two further points in the Welsh Government summary apply even where the conservatory is exempt. First, any new structural opening between the conservatory and the existing house requires building regulations approval, even if the conservatory itself is an exempt structure. Second, it advises against building a conservatory where it will restrict ladder access to windows serving rooms in roof or loft conversions, particularly if those windows are intended to help escape or rescue if there is a fire. This is a practical warning about the position of the conservatory and the windows above it, and is worth raising with the installer and the local authority at the design stage.

If the conservatory is not exempt

A conservatory that does not meet the exemption, for example because the house heating will be extended into it, is an extension for which building regulations apply. Our guide to choosing building control explains the routes for England, and the Welsh Government publishes the approved documents for Wales on its building regulations pages. The planning rules for Wales are separate and are covered in our guide to conservatories in Wales.

FAQs

Is a conservatory exempt from building regulations in Wales?

Normally, according to the Welsh Government, if it is at ground level, under 30 square metres, thermally separated, not heated by a fixed appliance or the house system, and its glazing and electrics comply.

Do I need approval to knock through from the house?

Yes. The guidance says any new structural opening between the conservatory and the house requires building regulations approval.

Does safety glass apply to conservatory doors?

The guidance on doors and windows says safety glazing is needed in critical areas, including within glazed doors up to 1500mm from floor level.

Can a conservatory block a fire escape window?

The Welsh Government advises against building where it will restrict ladder access to windows serving loft or roof rooms, particularly windows intended for escape or rescue.

The bottom line

A conservatory in Wales is normally exempt from building regulations if it is at ground level, under 30 square metres, thermally separated from the house, free of fixed heating and compliant on glazing and electrics, but opening the house wall up and blocking loft escape windows are separate concerns. Anything outside the conditions needs building regulations approval. This is general information, not legal advice; confirm the position with the local authority building control team.

Sources

This guide draws on the following primary sources, current as of 24 September 2026:

• GOV.WALES, “Building regulations: conservatories”
• legislation.gov.uk, “The Building Regulations 2010, Schedule 2: Exempt buildings and work”
• GOV.WALES, “Building regulations: doors and windows”
• GOV.WALES, “Building regulations: electrics”

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.