If you work around smoke ventilation systems, you will constantly hear people mention Approved Document B, often shortened to Part B.
It is one of the main pieces of fire safety guidance used within UK Building Regulations and plays a major role in how smoke ventilation systems are designed within buildings.
Approved Document B helps guide how buildings should be designed to improve fire safety, protect escape routes, and support safe evacuation during a fire.
For smoke ventilation projects, it is often one of the starting points for understanding:
- Whether smoke ventilation is required
- What type of system may be needed
- Where vents should be positioned
- How escape routes should be protected
What Is Approved Document B?
Approved Document B is government guidance designed to help buildings meet the fire safety requirements of the Building Regulations.
The guidance focuses on protecting occupants, limiting the spread of fire and smoke, and supporting firefighting operations within buildings.
Importantly, Approved Document B is guidance rather than a product standard. It helps define what a building needs to achieve from a fire safety perspective, but it does not certify individual products.
Approved Document B Volume 1 & 2
Approved Document B is split into two main sections:
Approved Document B Volume 1: Covers dwellings such as houses and some residential properties.
Approved Document B Volume 2: Covers buildings other than dwellings, including apartments, commercial buildings, schools, offices, and more complex developments.
Smoke ventilation systems are most commonly associated with Volume 2 guidance, particularly within apartment buildings, corridors, stairwells, and smoke shaft systems.
The Main Objectives of Approved Document B
Means of Escape (B1)
Buildings must provide safe escape routes so occupants can evacuate during a fire. Smoke ventilation systems help keep stairwells, corridors and lobbies clear of smoke, making this one of the key areas where Approved Document B affects system design.
Internal Fire Spread (B2 & B3)
These sections focus on limiting the spread of fire and smoke through measures such as compartmentation, fire stopping and smoke containment. For smoke ventilation systems, this influences how smoke shafts, dampers and vents are integrated into the building’s fire strategy.
External Fire Spread (B4)
Approved Document B also includes requirements for external walls, roof coverings, boundary distances and openings. These can affect the location and design of roof vents, façade louvres and other external smoke ventilation products.
Firefighter Access & Facilities (B5)
Buildings must provide suitable facilities to support firefighting operations. This can influence the location of smoke control panels, override switches, firefighting shafts and smoke ventilation controls to ensure emergency services can operate the system safely.
You can download the latest edition of Approved Document B from the government website.
The Main Objectives of Approved Document B
| Section | What it Covers | In Practice |
|---|---|---|
| B1- Means of Escape | Safe evacuation routes for building occupants. | Smoke ventilation systems are commonly used to keep stairwells, corridors and lobbies clear of smoke, helping occupants evacuate safely. |
| B2 & B3 – Internal Fire Spread |
Fire resistance compartmentation, smoke containment and dampers |
Smoke shafts, control dampers and vents must work alongside the building’s fire strategy without compromising fire compartments. |
| B4 – External Fire Spread |
External walls, roof coverings, boundary distances and openings. |
May need consideration where smoke ventilation products penetrate or sit within the building envelope, such as façade vents, roof vents or roof AOVs. |
| B5 – Firefighter Access | Facilities and access for fire and rescue services. | Systems often include firefighter override controls, smoke control panels and strategically located vents to assist firefighting operations. |
You can download the latest edition of Approved Document B from the government website.
Approved Document B Changes
2026 Amendments
The 2026 updates are mainly focused on improving evacuation and stair provision within taller residential buildings.
Changes Include:
- A recommendation for more than one common stairwell in residential buildings over 18m in height
- New design guidance to support the use of evacuation lifts within blocks of flats
This means many taller residential buildings are now being designed to standards such as BS 9991, which is often considered more stringent than the current Approved Document B guidance.
2029 Amendments
The planned 2029 amendments are more focused on fire testing standards and product classifications.
The main change is the gradual removal of older national fire resistance classifications, moving fully towards European testing standards such as the BS EN 13501 series.
For smoke ventilation and fire safety products, this means testing and classification methods will continue moving towards more modern and consistent European fire testing frameworks.
Related Resources
At Rocburn, we understand the critical role smoke control systems play during a fire. That’s why all our systems are designed in accordance with recognised standards such as:
Our dedicated team of specialists are on hand with expert support, guidance and advice to ensure that you get the right products for your needs. Get in touch with us to gain a better understanding of how we can help you.
