Small single stair blocks of flats

[mevans421]

I wondered if anyone had knowledge of the origins of why ADB2, diagram 9b states that where flats open directly onto the protected stair they should be limited to 2 per floor?  As said, I am keen to understand the origin of the constraint so that I can then understand why it is considered necessary by ADB.

[wee brian]

you are asking the wrong question.

Design codes relaxe requirements in very small buildings. This is for a number of reasons, such as practicality, proportionality and costs.

In this case, a common lobby is considered to be safer than relying on lobby protection within a flat (the doors get wedged or removed and nobody can see).

But in very small premises the common lobby takes up an awful lot of room so the code relaxes the provision. But it would still be better to have a common lobby.

Arguably with less flats per floor the number of people affected by a fire is reduced.

If you are trying to justify having three or four flats without a common lobby then you've missed the point.

[mevans421]

Hi WB

I am not trying to justify three or four flats; etc. on the contrary I'm asking the regulator how he has justified it.  What I am increasingly finding is that Building Regulators are letting more than 2 flats per floor be accepted.  When I question them they provide justifications of which I have listed some examples below.

i.   Flats have only one bedroom (although ADB doesn?t make any distinction and they have not provided any quantative risk analysis against this criteira.)
ii.   Flats will have smoke detection (although this is a requirement anyway so cannot be justified as a mitigating compensation.)
iii.   Flats will have protected lobbies (although this is a requirement anyway so cannot be justified as a mitigating compensation.)
iv.   Flats will have a communal fire detection system (although such an arrangement is considered to be detrimental to stay put policies as clearly documented in fire safety guidance.

As such I find myself, as do many other fire risk assessors having to dubiously justify the above, or otherwise stating to the client that significant compensating measures should be installed - which as you can imagine does not go down well.  Of course if I justify the above then I too could be accused of just making it up as I go along!

I actually understand the 2 flats rule was an arbitrary figure plucked out of the sky; however, if not adhered to anything goes!  When I raise this with the Building Regulators I get the usual brush off. 

Has anyone got similar experiences and has anyone ever resolved the matter with the regulator?

[wee brian]

I suppose i) might be reasonable in some cases but the rest sound pretty dodgy to me.

[kurnal]

Mevans421 it's more evidence of a broken system. It's a shame when standards are set for new buildings then ignored and bent beyond recognition by those charged with implementing them. But realistically there are very many old buildings that fall far short of current standards - conversions, tenements and old buildings to the old PHA 1936 standards and there is no evidence of a problem creating a political pressure for change. Whether the new builds represent a higher risk than the old buildings - time will tell.

[Jim Scott]

What's an acceptable, probable, risk of fatality in such an arrangement?

Everything we do has an accepted value of risk.  Therefore, the same value (rightly or wrongly) is surely placed upon the probabilistic assessment of risk for multiple fatalities in a small single stair residential building.

I don't recall many multiple fatality incidents in these types of building.

[kurnal]

There's quite a lot of information on fire deaths in the home in the LGA guidance to flats, written by Toddy.

There's such a wide spectrum of risk out there - the Scottish tenaments with not a fire door between them, the converted historic mansions, those converted to the 1936 PHA codes, many of which have rotten steel escapes from upper floor Windows, the purpose built flats compliant with CP3 in its various editions and finally those constructed to ADB / BS9991. Many of the modern buildings are timber framed and use modular construction.
That's before you throw in height and social demographics.

My prejudiced view is that due to the enforcement regimes in place, the golden years for good fire safety in flats were those constructed to CP3 / BS5588-1 in the 1950s to the 1980s and that standards have declined since the 1990s. But as for statistics you are right Jim, and the range is too diverse and number of deaths too small to draw any conclusions. And is always likely to be.

 

[mevans421]

If I have interpreted the guides correctly I also notice that the DCLG sleeping accommodation guide states lobbies are required for all blocks of multi-storey flats.  Also the LGG guide only describes a small block of flats with 2 flats per floor.  Therefore, when we make an assessment that the above arrangement is ok we have to go against the guidance - which by some authorities is held as the benchmark. 

[kurnal]

I have not checked the sleeping accommodation guide  in preparing this response but remember this document is only a guidance document for a fire risk assessment and not a building design template. And all guides are just that- recommended guidance. The DCLG guides are by necessity generic and it would be wrong not to have regard to other guidance in carrying out a fire risk assessment.

 And you are right he problem with our industry at the moment is that the training and experience is fast disappearing through the window and people- enforcers and assessors alike with 4 days training on FRAs and no experience or underpinning knowledge in many  cases are losing all sense of perspective and hugging one guidance document or another as gospel and applying it  without regard to common sense and what is a holistic  practical fire safety view whilst on the other hand  AIs are falling over each other for business and applying their own relaxations to keep the client. And the fire services and government are only interested in taking any action once the horse has bolted and people have died so they have some hard statistics to work to.  I am glad I served is an enforcer and fire risk assessor in the golden days when people cared about standards and not just money. Why can't anybody see that service industries are productive and much more cost effective than paying people benefiits. End of rant.

[Davo]

But Prof, all the horses bolted when a certain guide was reprinted


davo

[AnthonyB]

If I have interpreted the guides correctly I also notice that the DCLG sleeping accommodation guide states lobbies are required for all blocks of multi-storey flats.  Also the LGG guide only describes a small block of flats with 2 flats per floor.  Therefore, when we make an assessment that the above arrangement is ok we have to go against the guidance - which by some authorities is held as the benchmark. 

Personally as the LGA Guide for fire safety in purpose built flats is a more recent document I wouldn't be using the DCLG guide as it's been superseded by this.

We are nearly 10 years on now since these guides were published, will they be reviewed?

[wee brian]

Agreed that you should be using the LGA guide for risk assessment in existing blocks but it shouldn't be used for New Buildings.

[AnthonyB]

No, ADB/DCLG Guide, or BS9991 or the BS7974 fire strategy depending on which was used for the build.

[Fishy]

What's an acceptable, probable, risk of fatality in such an arrangement?

Everything we do has an accepted value of risk.  Therefore, the same value (rightly or wrongly) is surely placed upon the probabilistic assessment of risk for multiple fatalities in a small single stair residential building.

I don't recall many multiple fatality incidents in these types of building.

There is, so far as I am aware, no benchmark numerical level of acceptable individual fire risk in any of the UK.  There is for other forms of 'general' H&S risk, but not for fire safety. 

Therefore, if one were to embark upon a probabilistic risk assessment, the only methodology that is likely to be acceptable is to undertake such an assessment of both the 'code compliant' solution and the 'alternative' solution.  If the individual fire risk associated with the latter is <= the former, then happy days (though societal risk also comes into the equation in some circumstances).

CIBSE Guide E has some guidance on the use of risk assessment in design & is worth reading for anyone thinking of embarking upon that course.  The HSE Guidance RR151 "Good practice and pitfalls in risk assessment" is also worth a read.

[Dinnertime Dave]

Agreed that you should be using the LGA guide for risk assessment in existing blocks but it shouldn't be used for New Buildings.

Doesn't it become an existing block as soon as it is occupied? The guide itself says

2.1 - This document is a guide to ensuring adequate fire safety in purpose-built blocks of flats, regardless of age.

3.1 - This guide is intended for buildings which have been constructed as purpose-built blocks of flats. It applies to existing blocks only. Fire safety design in new blocks of flats is governed by the Building Regulations 2010, but, once a block is occupied, this guide is applicable.

So it's only new for a nanosecond. If you are saying it isn't a design guide then Ok. But unscrupulous people will always treat it as such and dare the enforcer to take action.