Residential Sprinklers in Compliance with ADB

[Jon Barrett]

There seem to be difficulties in clearly understanding what are the requirements for sprinklers in residential for blocks over 30m as defined in the ADB.

This in my interpretation of how to satisfy the ADB requirements:

1. Does ADB allow resi sprinklers to be installed to 9251?
The ADB states that 'dwellings outside the scope of 9251' should be sprinklered to 12845.
But ADB also states that the 'limit on the scope of 9251 below 20m can be ignored' - so we DO fall within the scope of 9251 as defined in the ADB.
Therefore we can design to 9251

2. Do we need to provide full sprinkler coverage throughout the building?
The ADB states that ‘where a sprinkler system is specifically recommended within this document it should be provided throughout the building.
But ADB also states that ‘Sprinklers only need be provided in individual flats’.
Therefore corridors and common areas are unsprinklered.

3. Does the system need to comply with 12845 life safety requirements?
The ADB states that ‘any sprinkler system installed to satisfy the requirements of Part B should be regarded as a life safety system’.
Some people are reading this to mean that the life safety requirements of 12845 are to be applied.
BS 9251 states that ‘it covers systems installed for life safety purposes’.
Therefore BS9251 satisfies the requirements of the ADB.

Moving on to interpretation of 9251, for resi:

1. Flowswitches and audible alarms
For resi it states that... 'alarm arrangements should be in accordance with the authority having jurisdiction'
We should discuss and agree with the relevant authorities applicable to the project

2. Concealed and Recessed Sprinkler Heads
Is states that... 'Concealed and recessed sprinklers may be used with the approval of the authority having jurisdiction
We should discuss and agree with the relevant authorities applicable to the project

3. Pumped supply (for resi over 30m mains supply will be insufficient)
A single tank and single pump (no backup electrical supply required)

4. Pipework material
Plastic pipework can be used that complies with the relevant standards

Any comments and feedback on any of the above points would be appreciated.

Thanks,

Jon

[wee brian]

For 30m plus flats - Use BS 9251. Ignore the fact that 9251 is limited to 20m. Simple really - just read it with your brain turned on.

Dont see the point of fitting alarms to the sprinklers other than to warn you that its gone off by accident. (the flats will have smoke alarms)

[kurnal]

Dont have any experience of this at all so cant really help you in any meaningful way.
Presumably the 9251 sprinklers systems in individual flats will share a common water supply?
It would not be economic for each to have their own pumped supply and storage.

Would the block domestic supplies be pumped or by static head? Any circumstances/ subject to safeguards  in which these may be used for a 9251 system- like using the feed from the public main is permitted where flow and pressure are sufficient?

If you go for common stored water and pumped supply what capacity would we look for? 30 minutes duration in one flat? How many fires in how many flats would we cater for in calculating storage? To what standards would we install any common pipework and what would be the basis for calculation of flow? Would we install ring mains and isolation valves?

Sorry to hijack your thread with a load more questions  and sorry if these are banale- havn't had time to read up on 9251 for a long time.

[wee brian]

Its all in the standard - much easier than the BS EN for commercial buildings.

[peanut]

Sprinklers are only recommended in the dwellings themselves.  Hence the 'run-time' is 10 minutes (domestic, not residential sprinklers).

[Jon Barrett]

30 minutes storage required by 9251 for residential. Only need to consider one fire. Max. of 4 heads discharging.

I'm aware of people pushing resi above 30m to be to 12845 OH1/OH2 protection. The ODPM review of the cost effectiveness of sprinklers was based on a 9251 level of protection - it reported that 'resi sprinklers are probably cost effective for resi over 11 storeys'. 12845 system would not be cost effective.

[wee brian]

Well spotted peanut - Most people havent spotted that one.

ADB only asks for a domestic system so 10 mins it is.

[Jon Barrett]

I can't see reference to ADB ONLY asking for a domestic system - could you please quote the clause?

Thanks.

[Jon Barrett]

I can see how it might be read that the requirement only needs 'domestic' protection...

- ADB says sprinklers 'only be provided within the individual flats'
- 'individual flats' are defined as 'domestic' under 3.7 in ADB (could also fall under 'residential' (3.17) in ADB as 'apartment's fall under this definition)

BUT...

'Domestic' application restricts the size of any individual rooms in the dwelling to 40m2
'Residential' application allows the size of individual rooms in the dwelling to be increased to 180m2

Hence the logic of increasing the storage capacity from 10 to 30 mins for water storage. Also, 'domestic' only requires a max of 2 heads, 'residential' requires a max of 4 heads.

If the apartment rooms don't exceed 40m2 then a 'domestic' system could be used otherwise you'll need a 'residential' system.

[wee brian]

I'd go along with that. 40m2 is a big room.

[ian gough]

Hmmmm...10 mins goes quickly when you are located on a floor 30m and above. And don't even think of relaxing any other (passive) standards because of the sprinkler protection!

[kurnal]

How do you envisage sourcing the water for these individual BS9251 systems in these tower blocks? Surely we are not looking at individual storage for each flat- and if we are not then the 10mins/ 30mins argument will become academic.
Again excuse me if I am out of touch- I havn't yet bought the BS and am still relying on the DD- Will buy it when I have a paying query!

[wee brian]

One supply and pump - 10 minutes worth of water in the tank for two heads.

Of course if you are trading off (design freedoms as thay call them these days) then I would definately up the spec.

[peanut]

ADB clearly states that the systems are only required within individual flats, and that a BS 9251 (& in turn a DD 252) system is sufficient (note that ADB is thus recognising a DD as a design standard).

BS 9251 clearly states that systems within individual flats should be designed to a domestic standard.

10 minutes may not sound long, but it is 10 more minutes than a flat which less than 30 metres above ground, where the probability of fire is higher.

[kurnal]

So Wee B to be clear lets say we have a 25 storey block of flats wth 12 flats per floor and sprinklers over the 30m level, are you  proposing  180 sets of pumping equipment and 180 1000 litre tanks or 1 pump set and one 1000 litre tank between the lot?

Myself I would gold plate the BS and go for something like  two  10000 litre tanks and pump sets in the roof space of the block  shared between the lot, so that we have resilience for maintenance, can cater for more than one flat having a fire on any day and due to the height to maintain the sprinklers for as long as it takes for the fire service to attend, to climb to the top floor and to get their equipment to work however long it takes. That way we would have continuity of attack on the fire.

But I am making it up as I go along- why doesnt it say something like that in the BS and the AD?