Existing Dwellings protected stairway enclosure

[Kevin99]

Hi

I am looking for any approved codes that can help answer my concerns in regards to existing and purpose built blocks of flats of up to 3 or 4 floors with a single staircase and single final exit, being the front door.  

In particular my concern is in regards to  external windows.

In some properties the stairway has windows which are sealed casement units and cannot be opened.  In other properties these same windows have openers, either with or without locks.

Are these windows to be kept locked, can they be considered of use to allow smoke to exit or a risk allowing oxygen to fuel a fire?

I've been through the approved codes I have to hand but cannot find a definitive answer and/or reference.

I am appreciative of your thoughts in advance.

[AnthonyB]

In small existing older blocks of certain configurations openable windows can replace the automatic vents or openable vents that would normally be required for smoke control.

[Kevin99]

Thank you Anthony

In blocks of existing flats from house conversions or purpose built blocks of flats up to 4 storeys which have windows in the staircase, the only means of escape, we find some blocks where the windows are sealed units (unopenable) and some have openers (with or without locks fitted), are both allowed/correct and if so where may I reference this (an approved code) such as say BS9991 or Building Regs Approved document B etc.?

Kind regards

[AnthonyB]

Normally windows don't have a fire safety role in the common areas of flats as smoke control is provided in other ways - so they aren't addressed by BS9991 or ADB as they aren't a fire safety feature.

The openability of windows only becomes a concern when there are no openable vents, AOV's or smoke shafts.

[Kevin99]

Hi Anthony

Thank you.

I found this side note in   BS-9999-2008-Code-of-Practise-for-Fire-Safety-in-Design Management-use-of-Building.pdf which kind of verifies your answer.

28 Heat and smoke control

28.1 General

The build-up of smoke and heat as a result of a fire can seriously inhibit the ability of the fire service to carry out rescue and fire-fighting operations within a building.

Means should be provided to ventilate the fire-fighting shaft of smoke.

The objective of such ventilation is to minimize the possibility of serious contamination of the fire-fighting stairwell (see 28.2), although some smoke contamination of the stairwell is possible if natural ventilation is provided.

Products of combustion from basement fires tend to escape via stairways, making access difficult for fire service personnel. Providing outlets for smoke can reduce this problem. Venting can improve visibility and reduce temperatures, making search, rescue and fire-fighting less difficult (see 28.3).

Thank you again!

[AnthonyB]

Not sure if you have already looked but this is pretty much the guide for existing flats https://www.local.gov.uk/sites/default/files/documents/fire-safety-purpose-built-04b.pdf

[Guest Cedric L]

This is a great question. My understanding is that there is only a need to provide smoke ventilation from the stair if its classed as a fire fighting shaft, BS 9999 table 17 specifies when a fire fighting shaft is needed. 

Some clarification would be great though.

If the stair is not a fire fighting shaft does it still require some form of smoke ventilation? 

[AnthonyB]

You are using the incorrect guidance - BS9999 is not for flats and is for designing new non domestic buildings. Blocks of flats have far more onerous smoke control requirements due to their fire strategy being of stay put.

Existing flats should be assessed to this guide (& then it's impending replacement)

https://assets.publishing.service.gov.uk/government/uploads/system/uploads/attachment_data/file/1020410/Fire_Safety_in_Purpose_Built_Blocks_of_Flats_Guide.pdf