In England the Class 7 building regulations exemption for a conservatory of up to 30 square metres applies only if any glazing satisfies Part K, and requirement K4 says glazing in locations where people are likely to come into contact with it must break safely, resist impact or be shielded; Approved Document K (2013 edition) explains how.

Why glazing is a condition of the exemption

Our guide to the Class 7 exemption explains that a ground-level conservatory of up to 30 square metres is exempt from the Building Regulations if certain conditions are met. Schedule 2 to the Building Regulations 2010 adds that, where a conservatory or porch is wholly or partly glazed, the glazing must satisfy the requirements of Part K4, K5.1, K5.2, K5.3 and K5.4 of Schedule 1. For Wales the legislation refers to Part N instead, which our guide to Wales building regulations covers. The Planning Portal likewise says a conservatory is normally exempt when its glazing and fixed electrical installations comply with the applicable requirements. This guide covers England.

What requirement K4 says

Requirement K4 in Schedule 1 says glazing with which people are likely to come into contact while moving in or about a building shall, if broken on impact, break in a way unlikely to cause injury, or resist impact without breaking, or be shielded or protected from impact. Approved Document K, the 2013 edition for use in England, gives guidance on meeting it. GOV.UK notes that this edition combined the former Approved Document N on glazing into Approved Document K. The document is guidance, and it says there is no obligation to follow it if another route to compliance is shown.

Requirements that do not apply to dwellings

The approved document sets out four further requirements, K5.1 to K5.4, covering collision with open windows, marking of large glazed areas, safe opening and closing, and safe cleaning access. Each carries a limit on application: K5.1, K5.2 and K5.3 do not apply to dwellings, and K5.4 does not apply to dwellings or to elements not intended to be cleaned. The K4 section in the approved document carries no such exclusion, so the impact requirement is the one most relevant to an extension of a house.

Critical locations

Approved Document K says the risk of cutting and piercing injury is greatest for glazing in doors and door side panels and at low level in walls and partitions, where children are especially vulnerable. Diagram 5.1 shades the critical locations in windows and in doors and their side panels, using dimensions of 300mm, 800mm and 1500mm measured from floor level. In a conservatory, glazed doors, side panels and low-level glazing are the elements to check against the diagram.

The routes to compliance

Paragraph 5.2 lets a designer comply in critical locations in one of three ways.

• Safe breakage: glazing that satisfies Class 3 of BS EN 12600 or Class C of BS 6206. In a door or door side panel with a pane width over 900mm, Class 2 of BS EN 12600 or Class B of BS 6206 is acceptable.
• Robustness or small panes: glazing that is robust, for example thick annealed glass or inherently strong material such as polycarbonate, or small panes. A small pane is an isolated pane or one held in glazing bars, with a maximum width of 250mm and an area not exceeding 0.5 square metres, and annealed glass in small panes should be at least 6mm nominal thickness, or 4mm in traditional leaded or copper lights where fire resistance is not important.
• Permanent protection: a permanent screen that prevents a 75mm sphere from touching the glazing and is robust.

What to ask the installer

A buyer can ask the installer to identify each pane in a critical location, state which route to compliance is used and supply the product marking or test class for the glass. The broader glazing choices, such as U-values and solar control, are covered in our guide to conservatory glazing, and door security in conservatory doors and security.

FAQs

Is safety glass a condition of the Class 7 exemption in England?

Schedule 2 to the Building Regulations 2010 makes the exemption for a glazed conservatory conditional on the glazing satisfying Part K requirements, and K4 covers impact safety.

Which British Standard classes does Approved Document K accept?

Class 3 of BS EN 12600 or Class C of BS 6206, and for a door or side panel with a pane width over 900mm, Class 2 of BS EN 12600 or Class B of BS 6206.

Does the same approved document apply in Wales?

No. The legislation refers to Part N for Wales, and Approved Document K (2013 edition) is stated to be for use in England.

Can a permanent screen replace safety glass?

Approved Document K says glazing protected by a permanent screen that meets its conditions does not itself need to comply with K4.

The bottom line

In England, glazing in a conservatory that relies on the Class 7 exemption must still meet Part K, and the impact requirement K4 is the one that applies to dwellings. Approved Document K allows safe-breakage glass, robust or small panes, or a permanent screen in the critical locations shown in its Diagram 5.1. Checking each pane against those zones and standards at the design stage avoids a later dispute over whether the exemption applies. This is general information, not building control advice; confirm the position with the local authority or a registered approver.

Sources

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

• GOV.UK, “Approved Document K: protection from falling, collision and impact (2013 edition for use in England)”
• GOV.UK, “Protection from falling, collision and impact: Approved Document K”
• legislation.gov.uk, “The Building Regulations 2010, Schedule 2: Exempt buildings and work”
• legislation.gov.uk, “The Building Regulations 2010, Schedule 1: Requirements”
• Planning Portal, “Conservatories: Building regulations”

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.