Automatic Opening Vent Building Regulations 2026

From 30 September 2026, automatic opening vent building regulations in England will be affected by new updates to Approved Document B, with important implications for the design of fire safety and smoke control systems in certain new residential buildings. The changes introduce new provisions relating to second staircases in residential buildings with a storey at least 18 metres above ground level.

Understanding these regulations is important for anyone responsible for the design, installation or ongoing management of a building with an AOV or smoke control system.

What Are the Automatic Opening Vent Building Regulations?

There isn’t one single regulation covering every AOV installation. Requirements for smoke ventilation depend on the building’s design, use, height, means of escape and overall fire safety strategy.

Approved Document B provides guidance on meeting the fire safety requirements of the Building Regulations. Its guidance includes provisions for smoke control of common escape routes using natural smoke ventilation.

For example, the existing guidance for relevant residential arrangements includes smoke vents serving corridors or lobbies next to stairs, with requirements concerning their location and free area. The guidance also sets out arrangements for vents connected to smoke shafts.

This means an AOV shouldn’t be selected simply because it is suitable for a particular opening. The vent needs to form part of an appropriately designed smoke control system.

What is Changing in 2026?

The 2026 amendments to Approved Document B introduce a new requirement for second staircases in new residential buildings over 18 metres. The amendments come into force on 30 September 2026, subject to transitional provisions.

The change is significant for developers because the introduction of another staircase can affect the overall layout and fire safety strategy of a building.

Where corridors, lobbies and staircases form part of a smoke control arrangement, changes to the building layout need to be considered alongside the smoke ventilation system.

It does not mean that every existing AOV system automatically needs replacing because of the 2026 amendments. The requirements applying to a particular project will depend on the building, the proposed work and the relevant transitional arrangements.

AOVs and Buildings Over 18 Metres

The 18-metre threshold is particularly relevant to new residential buildings.

The government’s consultation response explains that the decision to introduce a second-staircase threshold at 18 metres was intended to align with the high-rise building threshold under other building safety legislation and guidance.

For developers working on new high-rise residential buildings, smoke control should therefore be considered alongside the design of escape stairs, corridors and lobbies.

This is especially important where the building uses natural smoke ventilation through AOVs. Changes to the number or arrangement of stairs can affect how the smoke control strategy needs to operate.

The design should be considered as a complete system rather than treating individual AOVs as standalone products.

What About Evacuation Lifts?

It is important to distinguish between confirmed 2026 amendments and proposals that are still being considered.

In March 2026, the government launched a review of Approved Document B, including proposed provisions for evacuation lifts in new residential buildings above 18 metres. The consultation proposed a minimum of two stairs and two evacuation lifts in these buildings, with the option for a firefighting lift to serve a dual function where one is already provided. These evacuation-lift provisions were proposed changes and should not be confused with the separate second-staircase requirements coming into force from 30 September 2026.

However, the consultation is relevant to anyone involved in the design of new high-rise residential buildings because it highlights the increasing complexity of smoke control and evacuation arrangements.

The consultation itself notes that second staircases and evacuation lift lobbies can create challenges for smoke control system design, particularly in buildings with complex layouts.

Do Existing AOV Systems Need to Be Upgraded?

Not necessarily.

The introduction of new guidance does not automatically mean that every existing AOV system needs to be replaced. However, an existing system should be assessed if building work is being planned or if alterations could affect the building’s fire safety strategy.

It is also important to investigate any existing faults. An AOV system that is not operating correctly should not simply be left because the system was compliant when it was originally installed.

Regular testing, maintenance and appropriate repairs help ensure that the system continues to perform as intended.

For high-rise residential buildings covered by the Fire Safety (England) Regulations 2022, there are also specific requirements relating to routine checks of smoke control systems. Monthly checks are required, including making sure that the smoke control system responds to signals from the associated fire detection and fire alarm system and any manual controls provided for the fire and rescue service. Records of these checks must be kept.

What Should Building Owners Consider?

If you own or manage a building with an AOV system, it is worth keeping the following points in mind:

• Know what type of smoke control system is installed.
• Keep records of testing, servicing and repairs.
• Investigate faults rather than repeatedly resetting the system.
• Make sure alterations to the building do not unintentionally affect the smoke control strategy.
• Consider AOV requirements during the early design stages of refurbishment or new-build projects.
• Use appropriately competent professionals for specialist AOV work.
• Check whether proposed building work is affected by the latest Approved Document B provisions.
• Make sure the system is maintained in accordance with its design, relevant standards and manufacturer’s requirements.

For higher-risk residential buildings, building control requirements can also apply to building work. The Building Safety Regulator states that higher-risk buildings include those that are at least 7 storeys or 18 metres high and contain two or more residential units, as well as hospitals and care homes meeting the relevant criteria.

Why AOV Installation and Maintenance Matter

Understanding automatic opening vent building regulations is only one part of managing a smoke control system.

An AOV needs to be appropriately designed for the application, correctly installed and kept in working order throughout its service life. A fault with an actuator, control panel, power supply, battery or wiring could affect the operation of the wider system.

For developers, getting the smoke control strategy right at the design stage can help avoid costly changes later. For building owners and managing agents, keeping existing systems properly tested, serviced and maintained provides a clear record of their condition and helps identify faults when they occur.

The 2026 changes to Approved Document B make this an increasingly important consideration for new residential developments, particularly those reaching or exceeding the 18-metre threshold.

For any new installation, refurbishment or significant alteration, the applicable building regulations and fire safety requirements should be assessed at the design stage so that the AOV system is appropriate for the building and its intended use.

If you have questions about your AOV system or upcoming building works, contact us to discuss your requirements. We provide AOV installation, servicing, maintenance and repair for residential and commercial buildings across London, Surrey and the South East.