Residential Sprinklers in Compliance with ADB

[peanut]

The BS clearly defines individual flats as requiring domestic systems, not residential.  How can this be interpreted otherwise?

The flat is treated as an individual dwelling and thus requires the same level of protection as a house.  There is no impact on the remainder of the building to be considered.  That is the difference between a domestic and residential system.  Of course, if you have a hotel, care home etc.. then there is less significantly less compartmentation and thus the residential system is required.

Does any one think that BS 5839 needs amending to stop domestic smoke alarms being installed in flats?  If the residential sprinkler argument is valid then it follows that only BS 5839 Part 1 systems are acceptable in flats.

[Jon Barrett]

The BS clearly defines individual flats as requiring domestic systems, not residential.  How can this be interpreted otherwise?

When is a 'flat' (listed as domestic) not an 'apartment' (listed as residential)?!

If the building is over 30m then I would suggest it's an apartment block and therefore should be designed to resi standard.

The resi definition makes reference to height whereas the domestic definition doesn't - again indicating that resi relates to tall buildings rather than low level blocks.

All very unclear.

[Jon Barrett]

Does any one think that BS 5839 needs amending to stop domestic smoke alarms being installed in flats?  If the residential sprinkler argument is valid then it follows that only BS 5839 Part 1 systems are acceptable in flats.

The ADB SPECIFICALLY states that 'flats' are to be provided with a detection and alarm system to 5839:part 6.

Unfortunately ADB fails to recognise that the designer has to make a choice between 'domestic' and 'resi' when referrring them to BS9251.

You can't equate terminology across different documents - just because ADB refers to resi over 30m as 'flats' doesn't mean that you only look to see what is required for 'flats' in 9251.

[peanut]

ADB SPECIFICALLY states that sprinkler systems are only required within individual flats and can be installed to BS 9251.

BS 9251 SPECIFICALLY states that flats fall within the 'domestic' standard.  If, for whatever reason, sprinklers were required in the common parts of a block of flats, or other apartment building such as an HMO, then the standard would be 'residential' in the common areas.  This is all very clear in 9251.

Equating terminology across different documents is exactly what should be done, espcially when one document references another.

[Jon Barrett]

9251 includes 'flats' in both categories - under domestic... 'individual flats', under residential... 'blocks of flats'

ADB clearly states (in 8.14)... 'BLOCKS OF FLATS with a floor more than 30m...' and 'sprinklers need only be provided within the INDIVIDUAL FLATS'

So I guess, in your interpretation, a 'block of flats' would include communal areas with rooms up to 140m2 but in the ADB's case you only have to sprinkler the 'individual flats' - and therefore only to domestic standard.

I can see where you're coming from but it's not exactly plainly obvious. It takes a lot of deciphering and can be read in other ways.

We certainly have extremes of views - considering this thread was started because a sprinkler contractor told us that on one of our projects we should be putting in sprinklers to BS EN 12845 and OH3!

[slubberdegullion]

Jon,

I have to agree with your flexible attitude and desire to find the most appropriate solution depending on the circumstances.

Peanut,

A couple of things....

This is what 9251 says about residential or domestic occupancies:

"Residential occupancies, for multiple occupation, not exceeding 20 m in height, include apartments, residential homes, houses of multiple occupancy (HMOs), blocks of flats, boarding houses, aged persons homes, nursing homes, residential rehabilitation accommodation and dormitories.

"Domestic occupancies include individual dwelling houses, individual flats, maisonettes and transportable homes."

What can we say about this?  

Well, first of all, the reference to the 20m limit should be disregarded completely.  It is now commonly accepted that this limit is inappropriate.

Now look at where flats appear.  Well, they appear in both descriptions (they don't make it easy, do they?).  But look at the general descriptions under each heading.  The residential occupancies are all larger buildings.  The domestic occupancies are all small buildings/premises.  

It's my belief, and that's all it is, that flats in blocks should have residential systems installed.

Next....

You use an analogy of fire alarm systems in blocks of flats, stating that part 6 systems are all that are required in individual flats.  Well that's true provided that the compartmentation is good between individual flats and that a fire in any one flat will not affect the residents in any other flat.  I might just agree with you that, if the compartmentation is good between flats, then all that is required is a domestic system in each flat.

What I would add, though, is that we would have to be absolutely sure about the compartmentation in the building to accept part 6 systems only or domestic standard sprinklers.

All in all, what is required in every case, as Jon has stated and restated, is a clear understanding of the needs of each particular building and a willingness to deal with a building in the manner that is most appropriate in the circumstances.

Stu

[kurnal]

Does anybody know why the threshold of 30m was chosen?
I recollect it was based on the BRE study commissioned by the ODPM on cost effectiveness of domestic and residential sprinklers but I think if we knew exactly who is at greater risk in apartment blocks higher than 30m and why at this height the risk increases and why it becomes necessary to enhance the passive measures with active measures then the issue would be clear.

Is the sprinkler to enhance the life safety of persons within an individual flat, or is it to protect others outside the flat involved by stopping a small fire in its early stages from becoming a bigger fire and thus ensuing that the  passive measures- compartment walls, floors and doors are not tested towards their limits because the consequences of a fire at this level are much more serious?

[wee brian]

Like all trigger heights its a bit arbitrary. 30m is used throughout the AD as a definition of a "tall" building.

Things don't magicaly change at 30m but what else could you do?

[kurnal]

It would help if we know who or what the sprinklers are there to protect. Throughout the ADB, (although we are addressing life safety issues)  its usually fairly clear whether a requirement is for the protection of general means of escape, specific parts of the means of escape ( internal layout of flats or users of mezzanines) , the elements of construction to make sure it stands up long enough to avoid risk, making sure that a fire cannot spread to affect too much of the building at any one time  or to provide access and facilities for firefighters.

I struggle to see which element these sprinklers are intended to support. If its purely for the occupants of the flat involved domestics should do it. But why are high buildings any higher risk than medium rise buildings in this respect? If its for anything else then residential MAY be some help- greater chance of controlling the fire before the fire service arrive.

[peanut]

I assumed we were talking about new build flats here, in which case we must assume that compartmentation will be good. If we cannot be sure of this then we would have to re-consider the way we deal with flats completely.

I am a bit confused about all this talk about a flat not being domestic if it is in a block.  When is a flat not in a block?  A flat on its own is a bungalow.

The BRE work looked at the incidence of fires in flats (blocks) of varying heights, and the upper height classification was 'over 11 storeys'.  Since ADB already makes reference to 30 metres I guess it was decided to adopt 30 metres as opposed to 11 storeys as the threshold for sprinklers.  The report also makes it clear that the sprinklers are intended to restrict fire growth within the flat.  To me, but maybe not everyone, this means the sprinklers are provided to protect the occupants of the flat of origin.  Afterall, there are very few instances of deaths on flats other than the one of origin.

Approving authorities should really look at the reasoning behind the new sprinkler 'requirement' before insisting on them in indiviual cases.  Since the study looked at flats of over 11 storeys, perhaps there would be an argument for flats in a 10-storey, 31m high building not to be fitted with sprinklers.  There is a nice comment in an article in the IFE journal (or whatever it is called now) about fire engineers using empirical calculations and calculating results to many decimal places.  I agree with the point in the article, and would ask approving authorities not to be so 'exact' when insisting on limits placed in guidance documents.

[Jon Barrett]

Sprinklers in these applications are there to protect the occupants within the compartment.

Once deviations away from the ADB are proposed - possibly extended distances and compartmentation rating reductions - then the 9251 requirements need to be reappraised to ensure the resilience and capacity of the sprinkler system is appropriate to compensate for any design freedoms.

Also, the application of domestic standard is probably fine for single height rooms less than 40m2 in size. But many apartments these days are being designed with mezzanines (i.e. a two storey space) and in this case I believe residential standard should be applied. You then end up designing the central system for 4 heads and 30 minutes anyway.

BS9251 mentions indivual flats and maisonettes under domestic - this could mean flats having their own entrances (not communal) - I used to live in a flat on a first floor that had its own entrance door at ground floor. Maisonettes would generally fall into the category of two story buildings.

This view would tally up with what Stu is saying in terms of the types of buildings being mentioned in 9251.

Taking this view, a building over 30m would fall into the 'block of flats' and hence 'residential' standard.

Although I think the logic of 'domestic' dealing with the apartments themselves and the 'residential' areas being for larger communal areas, such as communal lounges etc. makes sense.

The caveat to this is that all rooms in the flat should only be single height - if you have any mezzanines then I would suggest residential standard - as you could get more than 2 sprinklers activated due to the height of rise of the smoke from the lower level.