BS-5839 part 6 LD3

Dwelling fires are still falling in England from 28,504 in 2019/2020 to 25,408 in 2024/2025. That said the number of fatalities is creeping up 194 in 2024/2025 compared to 166 in 2023/2024 and 199 in 2022/2023

(source assets.publishing.service.gov.uk/.../FIRE0205.xlsx)

The guidance that supports the building regulations ADB v1 still up to 2029 only requires LD3.

BS 5839-6 does recommend a risk assessment before picking a category. And categories are short hand not straight jackets adding a extra detector does mean its becomes another category.

BS 5839-1:2019 + A1:2020 recommends LD2 for new dwellings. Plus it is starting its review in January so start your ideas on how it should be changed now!

mapj1 said:

What changes over time is what level of protection is cost -effective, and rather like what sort of medicines the NHS will pay for, that depends partly on the value placed on a life and partly on how the materials cost tend to fall over time.
So If you think one life saved is say 1 million pounds (and that is probably not true but hey ho), but installing a basic fire detection system costs say £50 (battery smoke alarms on double sided tape) then only one in every 20,000 such systems needs to save a life for the exercise to have been worthwhile. But a more complex  system costing say £500 to install is not worthwhile unless you can be sure that for every 2000 systems you install, a life is saved. 
As noted cost to retrofit is far higher than to fit to new build, but even new build the cost is still not zero.
But things like wireless linked bases may lower the cost of something more sophisticated that was once too expensive, back to being worthwhile again.

Not sure I fully agree there Mike.  When I was growing up in the UK in the 1970 and 80s few house domestic houses had smoke alarms.  Any that did probably only had 1 for the whole house.  Now in the 1980 I remember campaigns to get a smoke alarm for your home for your family safety.   BUT the push became significantly stronger in the 1990s following new UK building regulations.  

These days people understand from past history/campaigns/building regulations and general awareness that 2 smoke alarms in the average 3 bed semi is more prudent.  I do agree that the cost of smoke alarms has reduced.  

As an example

Screwfix do a battery operated smoke alarm £6.99 as it most basic offering (Smith & Locke KD-129H Battery Standalone Smoke Alarm (747CG))

or 

Hispec Fast Fix PE/FF Mains Interlinked Optical Smoke Alarm (361RG)  £18.50

Other brands and other wholesalers are availabel

Thus for less than £100 you could get 3 interlinked mains units with battery backup for an average domestic dwelling.  IF mains power is cost prohibative due to labour or build fabric them battery power and interlinked is still an option but fractionally more exspensive but lets say less the £150.  So I put it to you and the community at large.  

What is the cost/value of the/a person for an average 3 bed semi against £150.  Remember, people are not just values or numbers, they are someones family or loved ones.

mapj1 said:

What changes over time is what level of protection is cost -effective, and rather like what sort of medicines the NHS will pay for, that depends partly on the value placed on a life and partly on how the materials cost tend to fall over time.
So If you think one life saved is say 1 million pounds (and that is probably not true but hey ho), but installing a basic fire detection system costs say £50 (battery smoke alarms on double sided tape) then only one in every 20,000 such systems needs to save a life for the exercise to have been worthwhile. But a more complex  system costing say £500 to install is not worthwhile unless you can be sure that for every 2000 systems you install, a life is saved.

I have a figure of £1m at the back of my mind, but we could say £2m to account for inflation.

These alarms do not prevent fires, nor do they put them out. We could add injuries to people and property to the equation, but it seems that the BS 5839 systems are intended to allow occupants (more) time to escape. So, if the aim is to reduce mortality, it begins to look like a public health question and it is indeed, "rather like what sort of medicines the NHS will pay for".

It seems beyond doubt that reducing excessive blood pressure (hypertension) reduces the risk of stroke and heart attack. If a pharmaceutical company wanted to bring a new anti-hypertensive to the market, it would have to show that it was more effective (in terms of mortality or morbidity) or at least as effective, but cheaper than existing drugs. So they are not comparing new drug against nothing, but new against old. Undoubtedly, a randomised controlled trial would be involved from which number needed to treat could be calculated.

Similarly, one could compare LD2 and LD3 protection: how many LD2 systems need to be installed to save one extra life?

But now we have a problem. Could we do a randomised controlled trial? One of the Government's proposed new towns would do. Fit half the properties to LD2 and half to LD3. Then, ignoring any ethical considerations, wait 50 years and hope that sufficient fires break out to allow a meaningful comparison.

What is the cost/value of the/a person for an average 3 bed semi against £150.  Remember, people are not just values or numbers, they are someones family or loved ones.

So for say, 20 million houses in the UK (there may be more by now) that's £ 3 BILLION - what could be done with that sort of money? Cure for another cancer? Thousands of urgent operations brought forward? Better care for the elderly? Are you going to tell their loved ones that they're less worthy than a plastic box on loads of people's ceiling's that 99.99% of the time provides no benefit whatsoever?

No easy answers.

  - Andy.

Will Lloyd said:

(source assets.publishing.service.gov.uk/.../FIRE0205.xlsx)

The link did not work for me, but I think that I have found the data.

I was going to ask how many of you have experienced a building fire, but ...

25,000 fires per year does not seem a huge number. However, given that there are 50-odd million of us, and allowing for an average household of two, that is a chance of being in a dwelling on fire in any year of approximately 1:1000, or 1:20 over 50 years.

I have had my experience! In fact the fire was in the landlord's quarters in my local (as in next door) pub about 45 years ago. If there was an alarm system, it was not installed there. When the alarm was raised - smoke was pouring out of the bedroom window - I dashed upstairs with a fire extinguisher, but the fire was way beyond that.

Happily, nobody was injured and rather unexpectedly, the pub was open for evening service.

No alarm would have made any difference, but the 2nd floor was used for B&B accommodation, and IIRC, any escape route would have been past the bedroom door.

I think that in this instance, LD2 would not have helped, but LD1 could have made a difference.

Back to Will's data: a drop of a third in the number of fires over 15 years seems impressive. However, as with the reduction in mortality due to stroke and heart attack, it may have more to do with the reduction in smoking rather than any other intervention.

I am not sure why it would cost the government or the people £ 3 BILLION.  As I stated previously you could get the kit from ScrewFix (other sellers are also available) for an interlinked system for between £100 to £200 for the average 3 bed semi 

 Afraid that Andy's figure seems to assume that nobody has any smoke detectors/alarms yet!

HMG promises to build (i.e. hoping that the private sector will build) 1.5 million homes during its 5 years in office. So at £150 a pop, that is £225 million.

One really good jackpot in the Lottery!!!

So the parts alone are £200, what does it cost to retrofit to a building and then make good ? I presume perhaps a day, maybe two, so more like 300-400 all up.  So we do that for 20 million house-holds and that is 20*300 = 6000 million, maybe 20*400 - 8000  so between  6-8 billion. You are right - it would be a serious investment.

Could we save enough extra  lives over the life of such an investment  (perhaps 10-20 years) compared to that money spent another way?  After all the folk dying from all the other things we don't do instead so we can afford to do just this are also someone else's loved ones. There is no truly free lunch. 

I'm not saying we should not uplift the recommended standards - far from it,  just that there is an argument for putting our money most carefully where it has most effect  - cost benefit analyses are not some obscure excuse not to do things, they do serve a very real purpose. We do need to be able to clearly justify why a more complex and expensive recommendation is to be preferred.

To my mind Chris's thought experiment is correct, but very hard to sell morally.

Mike. 

Afraid that Andy's figure seems to assume that nobody has any smoke detectors/alarms yet!

As a first approximation yes. But then consider that most alarms seem to come with a recommendation to replace after 7-10 years ... so you might then see the £3B as being less of a one-off investment, but an every decade recurring cost.

   - Andy.

The current government (Labour) came into power July 2024 with the ambition of 1.5 million new homes during their term in parliament.  The next general election must be called by August 2029. The general election MAY be called earlier.  I very much doubt they(Labour) or any UK government can achieve this objective during A/The 5 year Parliamentary term.  This point is however mute in this discussion as all new design and builds for domestic dwellings need/will need to meet an LD2 category due to
BS7671
BS5839
Building regulation and Approved Documents.  

The LD3 category would only really affect the existing housing stock in the UK except for Scotland.  Now of that, roughly 25 million housing stock in England about 1/3 are rented.  Thus they will/SHOULD be covered by things like PRS (Private Rented Sector) and social housing.

New builds only have to meet LD3 as that all the approved document requires (England) and the approved document has been 

revised with current revisions going up to 2029 I cannot see this changing anytime soon

New builds only have to meet LD3 as that all the approved document requires (England) and the approved document has been 

revised with current revisions going up to 2029 I cannot see this changing anytime soon

Will Lloyd said:

New builds only have to meet LD3 as that all the approved document requires (England) and the approved document has been 

revised with current revisions going up to 2029 I cannot see this changing anytime soon

The Approved Document is slightly ambiguous. Paragraph 1.1: All dwellings should have a fire detection and alarm system, minimum Grade D2 Category LD3 standard, in accordance with the relevant recommendations of BS 5839-6.

The phrase, "all dwellings" includes existing and new buildings. Whilst Table 1 of BS 5839-6:2019+A1:2020 lists LD3 for some existing premises, the minimum for new or materially altered premises is LD2.

So, I interpret the Approved Document as recommending at least LD2 for new builds.