Fire Safety Design

[Guest Gary]

I am studying architecture and fire safety is an element of that.

I am wondering what is the difference between a protected lobby and a protected corridor?

I think it is that a lobby has 2 fire door separation from the corridor, 1 of which can be an internal Fire door within an inner hallway of a flat and the other being the flat entrance door, and a corridor is only 1 door between the apartments (say an open plan apartment)

Also once in a protected stair, does the stair need to exit direct to fresh air or can it be via a protected lobby or corridor?

And my final question is in the small buildings requirement – is there anything that can say that the property is 4 floors above ground? I am designing a building 11.4m from ground and 5 storeys. I only have space for AOV’s at the end of each corridor i.e no room for a smoke shaft.

[Tom Sutton]

A lobby is a room or short corridor used as an entrance hall, vestibule in a domestic property or leading to a staircase in larger buildings and can be protected. In a flat only the front door needs to be a full half hour standard, doors to rooms only need to be FD20, no S/C. Any well-fitting substantial standard door would be considered a FD20 door.

A corridor is a passage connecting parts of a building and can be protected or not depending on the circumstances, in a block of flats it will be a protected corridor.

Once in a protected staircase it must lead to ultimate safety (fresh air) and protected corridors top or bottom can be used to achieve this.

If you are using ADB then your building is not a small building it is more than three floors above the ground floor, it is more than 11 m check out C5 and 2.21, I think they have been served you a curved ball.

[AnthonyB]

If studying design you should be aware of the three approaches to compliance with the functional fire safety requirements of the Building Reglations:

Standard Approach: Following the prescriptive guidance in Approved Document B

Advanced Approach: Following the flexible design guidance in BS 9999:2017 Fire safety in the design, management and use of buildings. Code of practice

Fire Engineered Approach: Bespoke design (including computer modeling) using BS 7974:2001 Application of fire safety engineering principles to the design of buildings. Code of practice

These will all help you with definitions and solutions.