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Risk Assessment Query on Smoke ventilation in Blocks of Flats

Guest James

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Guest James

I’m currently looking at a number of older (pre-Building Regs 1991), low-rise (under 11m), low-risk, blocks of flats which pre-date the requirements for AOV’s, but instead have windows on each level, which according to the guidance taken from the Government Publication ‘Fire Safety in purpose-built blocks of flats’ (below), should be okay:


Small single-stairway buildings

 58.25 Where a single-stairway building is small, relaxations in the provisions apply, providing:

 • the top floor of the building is no more than 11m above ground level

• there are no more than three storeys above the ground level storey

• the stairway does not connect to a covered car park

• the stairway does not serve ancillary accommodation, unless the ancillary accommodation is separated from the stairway by a protected lobby or corridor with a permanent natural vent or ventilation by a mechanical smoke control system

• there is an openable vent provided on each floor level for use by the fire and rescue service, or alternatively, there is a remotely operated vent at the head of the stairway.


Benchmarks for existing blocks of flats with flats opening directly on to a single stairway

• Up to four storeys in height, should be acceptable in most situations, provided the stairway has openable windows or vents.


Benchmarks for existing blocks of flats with unsatisfactory smoke control

• In single staircase blocks up to six storeys, in which flats open directly onto the stairway, manually opening vents or windows would be acceptable.

It also says that such a recommendation to install an AOV would be unreasonably proportionate:

A1.2 This enables a sympathetic approach to old blocks of flats designed in accordance with superseded standards. It is not appropriate simply to apply current standards to such blocks, with no consideration of the risk to people from continuation of the original fire safety measures without expensive upgrading that is not proportionate to the risk. (By analogy, an old car may not incorporate all the safety features of current models but may still meet road traffic legislation.) Requirements for upgrading fire safety measures in such circumstances should be based on identification of material risk, rather than prescriptive application of current guidance.

23.5 It will often need to be accepted that it is neither realistic to meet current benchmark standards, nor risk proportionate to impose many of the solutions available today to the situations found in the designs of existing buildings.

The issue I currently have, is that the windows on the top-level floor are opposite to the direction of the stairs, and there is no extension to the top floor landing to lead to the windows, meaning that these windows on the top floor are unreachable, I’ve attached a couple of photos to try and explain.

My question is…….. is it reasonable that my assessment marks this as ‘safe’, as there are windows which could be used by the Fire & Rescue service (albeit, they would need to access the windows by a ladder), or should further controls be established, such as manual control arms, or remote switches, and is it not reasonable to assume that the Fire and Rescue Service could use the window if they required to ventilate smoke from the communal hallways, and would use a ladder if they needed to?

I’ve looked through all the legislation and guidance, but I can’t find an answer to this specific query. My presumption would be that as this was okay at the time, this should be okay now, as the guidance says?


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Short section of ladder in SCBA is unlikely to happen, they could vent to some extent from the landing set, although strictly speaking the higher ones should be the ones used.

It meets the spirit of the guidance so it's essentially how comfortable you feel with it in this situation.

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