Episode 111:
Hello and Welcome to the Part3 with me podcast.
The show that helps part 3 students jump-start into their careers as qualified architects and also provides refresher episodes for practising architects. I am your host Maria Skoutari and this week is a bonus episode on the recently released amendements to Approved Document B. Today’s episode meets PC3 of the Part 3 Criteria.
Just last month, amendments and updates were made to Approved Document B of the Building Regulations covering both Volume 1 and Volume 2 which relate to dwellings and buildings other than dwellings.
As I’m sure you are all aware, following the Grenfell tragedy, a number of updates have been made to Approved Document B in 2020 and 2022 which address fire safety precautions to be adhered to, to ensure the safety of occupants, firefighters and those close to the building in the event of a fire. It covers means of escape, the ability to internally isolate a blaze to prevent a fire from spreading, external fire spread, firefighter access to the building and facilities, fire detection and warning systems in place within a building. It also addresses the internal spread of a fire due to the structure or lining used within a building and safety measures related to this. The key changes from the 2020 and 2022 updates were the stricter requirements for buildings over 11m and the ban of combustible materials.
The key changes with this update which was release in March 2024, entails the requirement of a second staircase where a flat is on a storey that doesn’t meet the criteria for a single escape route or small single-stair buildings or where the building has a top storey of 18 metres or more. It also focuses on building design provisions to support the use of evacuation lifts in blocks of flats.
The 2019 edition of Approved Document B incorporating the 2020 and 2022 amendments will continue to apply up until 30th September 2026 where a building notice or an initial notice has been given to, or a building control approval application with full plans made to the relevant authority and either the building work to which it relates: a. has started and is sufficiently progressed before that day; or b. is started and is sufficiently progressed within the period of 18 months beginning on that day. After that date, the new regulations will apply released under these 2024 amendments.
High-risk buildings which follow the gateway processes will have a further 18 months until March 2028 to progress work on-site sufficiently or they must make a new application taking into consideration the change of guidance.
Architects should be aware of the new definition of ‘sufficiently progressed’ in Approved Document B, which aligns with the wording of legislation relating to higher-risk buildings (HRBs). Meaning, that building work is deemed to have been sufficiently progressed:
- where the building work consists of the construction of a building, when the pouring of concrete for the permanent placement of the trench, pad or raft foundations has started, or the permanent placement of piling has started; or
- where the building work consists of work to an existing building and when that work has started; or
- where the building work consists of a material change of use of a building, when work to effect that change of use has started.
Now, in terms of the Guidance Document itself:
It has been restructured to separate ‘Design for horizontal escape’ from ‘Design for vertical escape’ for residential buildings. Which states that from the entrance door of a flat, a single escape route is accepted:
- If every flat is separated from the common stair by a protected lobby or corridor and where the maximum travel distance for escape in one direction only is not exceeded, which is 7.5m
- Or is accepted if the flat is on a storey served by two or more common stairs, the flat is in a dead end of a common corridor and the maximum travel distance does not exceed 7.5m in one direction or 30m in more than one direction
The amended guidance provides tables and diagrams demonstrating these.
In terms of common stairs generally, flats should be served by more than one common stair if the flat is on a storey that doesn’t meet the criteria for a single escape route or a small single-stair building or where the building has a top-storey of 18m or more.
Another amendment includes how ‘interlocking stairs’ are considered. Approved Document B, now makes it clear that any interlocking stairs should be considered as a single escape route and would not constitute an alternative means of escape.
Another item highlighted within the amended guidance is that an escape route should not pass through another stair enclosure to reach an alternative exit, however, it may pass through a protected lobby (minimum 30 FR) to reach an alternative exit. A protected lobby should not provide direct access to more than one stair. Also, a common corridor connecting two or more storey exists, should be divided with a fire Doorset fitted with a self-closing device with a minimum fire rating of 30 minutes with smoke seals. There have generally been additional requirements included within the updated document regarding fire doorsets which is located within Appendix C.
In terms of ventilation, there should also be some means of ventilating the common corridors/ lobbies to control smoke and, therefore, protecting the common stairs. This means of ventilation offers additional protection to that provided by the fire doors to the stair, as well as some protection to the corridors/lobbies.
The Approved Document, now also states that a stair of acceptable width for everyday use will be sufficient for escape purposes. If it is also a firefighting stair or a common stair in a building with a storey 18m or more in height, it should be at least 1100mm wide. The width is the clear width between the walls or balustrades. Any handrails and strings intruding into that width by a maximum of 100mm on each side may be ignored.
It also adds that, in buildings designed for phased evacuation or progressive horizontal evacuation, if the lift well is not within the enclosures of a protected stairway or evacuation shaft, its entrance should be separated at every storey by a protected lobby (minimum REI 30). Where there are basements and enclosed car parks, the lift should be within the enclosure of a protected stairway or evacuation shaft. Otherwise, the lift should be approached only via a protected lobby or protected corridor (minimum REI 30).
Reference is also made within the amended guidance regarding evacuation lifts. In London, there is already a requirement that all new buildings taller than 18m should have an evacuation lift. Now there is also a requirement for throughout England, where evacuation lifts are provided, ADB says they should be located within an evacuation shaft containing a protected stairway, an evacuation lift and an evacuation lift lobby. The lift lobby should provide a refuge area for those waiting for the evacuation lift, have direct access to a protected stairway and not be directly accessible from any flat, maisonette, storage room or electrical equipment room. It also notes that the evacuation shafts should be afforded the same level of minimum protection as the stairway, whereby, any smoke control system designed to protect the staircase should extend the same level of protection to the evacuation lift and evacuation lift lobby.
To sum up what I discussed today:
- These March 2024 changes to Approved Document B make clear that a second staircase is required in all new tall residential buildings over 18 metres and confirm the end date for the transition period to the new rules which is 30th September 2026
- The 2019 edition incorporating the 2020 and 2022 amendments will continue to apply where a building notice or an initial notice has been given to, or a building control approval application with full plans made to the relevant authority before 30 September 2026 and either the building work to which it relates: has started and is sufficiently progressed before that day; or is started and is sufficiently progressed within the period of 18 months beginning on that day
- High-risk buildings which follow the gateway processes will have a further 18 months until March 2028
- Another changes within the new Approved Document B include, interlocked stairs should now be considered as a single escape route and “do not constitute an alternative means of escape”.
- Evacuation shafts are introduced to support the provision of evacuation lifts.
- Changes to provisions for fire doorsets have also been made and are outlined in Appendix C
- Provisions for horizontal escape and vertical escape are separated as per the structure of Volume 2.
