The need for intumescent seals on fire doors

[Tom Sutton]

Intumescent strips date back from the ark and were important in the days before AFD.

Not true Cleveland they arrived on the scene in the late seventies and at that time most certificated hotels was being fitted with AFD. But I will accept AFD was not as trusted as it is today and passive protection was preferred.

[CivvyFSO]

Regardless of the function they will perform, the strips & seals are simply there because a door would not pass the BS 476 test without them since a door can fail the test on the amount leakage. I believe that this was indeed a new requirement in the later 1970's, and I think Kurnal knows the proper BS where it all changed.

[Midland Retty]

Quite. But you would perhaps agree Civvy that when looking at existing fire doors it is overburdensome to insist that the doors be upgraded with intumescent strips. They do little to increase life safety (again unless we are dealing with buildings with stay put policies)

[CivvyFSO]

In the majority of cases yes, it would be unnecessary. Each case on its own merits though.

[hammer1]

Interesting.

I have visited many, many office buildings that have had major interior refurbishment 20 odd years ago in London over the years, in regards to Safety,Construction and Fire dealing with Property agents.

I must admit most cases existing fire doors have not been upgraded, and will never be for the main reason of cost. I may also add where inspecting fire officers have visited such properties this has not been an issue.

Maybe in the ideal World all existing fire doors would have these kind of upgrades, but not where I am sitting.

[kurnal]

This old thread may be of interest

http://www.kingfell.com/~forum/index.php?topic=3292.0

[Tom Sutton]

I hope I am not trying to teach my grandmother to suck eggs, if I am I apologize but the history may clarify some points.

Strips and seals developed separately and you have to consider them that way. Initially to pass a BS 476 part 8: 1972 test the doors were made of expensive hard wood filled with a FR material and 25mm stops. Fire door manufacturers looked for cheaper ways to produce them and the answer was intumescent strips which took quite a long time to develop also it was found 25mm doors stops were not necessary. By early 1980 fire door using intumescent strips was the norm and in 1987 a higher standard BS 476 Part 22 :1987 was introduced which was a  targeted at fire doors and it was argued the old part 8 doors would fail the new standard at least the ones without intumescent strips. This remains in force today together with the European standard BS EN 1634-1: 2000. 

In the seventies cold smoke seals were used on cross corridor fire doors to control any cold smoke in corridors and there was no BS test. We called them smoke stop doors and were usually 20mins FRSC doors fitted with cold smoke seals. BS 476-31.1 was introduced in 1983 which was the test for cold smoke seals. At some later date it was decided to control cold smoke in the room of origin and the designation FD30S appeared.

[Auntie LIn]

Hello chaps - see you're taking my name in vain again!   (Should spend less time working and more on FireNet I guess!).

Can I pick up on some of the things you've talked about?   (Here's Auntie Lin's potted lecture for the day)

BS476:  Part 8:  1972.   This standard developed because of research (Fire Research Station I think) which showed that when fire developed, the pressure in the fire compartment increased, and smoke and hot gases looked for more space to move into.   This led to the development of a positive pressure fire test (Pt and developments such as fire seals.   To be a Pt 8 door for anything more than 20 mins, it would have had to be tested with a fire seal fitted and therefore, in use would have needed the seal fitted in order to comply with its certification.

Paul2886 - interested in your comments about 'civilians and FRAs over the phone.   Had a very interesting chat yesterday with a lady who had been bullied by her local fire brigade into buying into something called FireSmart.   Anyone know anything about these people?

Davo - as it's a hotel we're talking about, shouldn't we consider the likely capabilities of the room occupants to respond to a fire (no - silly boys - not THAT sort of capabilities - whether they've sampled too many of the malts in the bar!)

Nearlythere - fit of the doorset is everything.   A well-fitting door (even gaps, not exceeding 3mm) may provide a reasonable level of protection, but I've done many surveys over the years and have yet to go to a building where all the doors are cared for to this level of fit.

Fishy - have to agree about the uselessness of 25mm stops.   The only thing they're really good for is allowing an incompetent chippy to throw the leaf into the frame and get paid and off site before anyone notices.   I was appalled a number of years ago when lecturing at FSC when one of my students calmly told me he always asked for 25mm stops "because otherwise the door won't touch the frame".

MidlandLion - what's wrong with property protection if you're a responsible building owner and employer?   Can't lay hands on the stats. like you guys, but I know that a significant proportion of businesses which have been involved in a fire never recover, and that's good enough reason for me.

TWS - just hi from one old git to another!   Yes, I've been round the block a few times and have seen both negative and positive pressure tests on fire doors.

Martin672 - do you want to contact me about surveys on doors?

There you are chaps - that should keep you all going for another ten minutes or so.   Auntie Lin is available to lecture at parties, bar-mitzvahs and working mens' clubs!

[Midland Retty]

MidlandLion - what's wrong with property protection if you're a responsible building owner and employer?   Can't lay hands on the stats. like you guys, but I know that a significant proportion of businesses which have been involved in a fire never recover, and that's good enough reason for me.

Hiya Auntie Lin - always good to see you - you must pop in more often !!!

I certainly dont disagree with you, and yes building protection is an important consideration, I was debating the point however that intumescent strips aren't provided generally for life safety reasons (except buildings with defend in place strategies)

[Tom Sutton]

BS476:  Part 8:  1972.   This standard developed because of research (Fire Research Station I think) which showed that when fire developed, the pressure in the fire compartment increased, and smoke and hot gases looked for more space to move into.   This led to the development of a positive pressure fire test (Pt and developments such as fire seals.   To be a Pt 8 door for anything more than 20 mins, it would have had to be tested with a fire seal fitted and therefore, in use would have needed the seal fitted in order to comply with its certification.

Between 1974 and 1979 I specified many half hour fire doors none I recall with intumescent seals and I also accept most were nominal fire doors (upgraded fire doors) and many will have been replaced because of the material used. However there will be many still in use today because this was the norm at that period. If it is considered that these doors are not fit for purpose then I need to see examples that these doors have failed and were considered a contributory factor in the death of some person. Incidentally property protection was never considered and that was left to the building regs.

If you was conducting a fire door survey and came across substantial well fittings doors with inch rebates with no heat seals would you insist they be fitted?

[Midland Retty]

Hi Tom

Intumescent strips aren't a life safety provision. They are fine for property protection or places with stay put policies, but otherwise if I came across most buildings and intumescent strips weren't fitted on any of their fire doors I'd simply recommend that when the doors are due for replacement any new doors should be fitted with the intumescent strips (and all the other bits and pieces, such cold smoke seals etc etc).

I certainly wouldn't be specifying on a deficiency letter that the doors must be upgraded with intumescent strips immediately or within three, six or twelve months for instance.

So whilst previous standards mentioned that one inch rebates meant you get away without fitting intumescent strips I would argue that if you came across a fire door with smaller rebates without intumescent strips you wouldnt deem it to be a huge problem that could possibly endanger lives.

[nearlythere]

Hi Tom

Intumescent strips aren't a life safety provision. They are fine for property protection or places with stay put policies, but otherwise if I came across most buildings and intumescent strips weren't fitted on any of their fire doors I'd simply recommend that when the doors are due for replacement any new doors should be fitted with the intumescent strips (and all the other bits and pieces, such cold smoke seals etc etc).

I certainly wouldn't be specifying on a deficiency letter that the doors must be upgraded with intumescent strips immediately or within three, six or twelve months for instance.

So whilst previous standards mentioned that one inch rebates meant you get away without fitting intumescent strips I would argue that if you came across a fire door with smaller rebates without intumescent strips you wouldnt deem it to be a huge problem that could possibly endanger lives.

You're obviously a critter with loads of common sense Midland Whoeveryouarenow. Unfortunately, and despite it's name, commonsense is not that common and you are most likely in the very high minority.
I have seen a report of a prosecution in this forum where someone was pinged for not having smoke strips on doors. Not, I might add, for failing to have fire doors which would be capable of resisting the passage of smoke ay ambient temperatures.
Two different things in my view. One is because most book says so, and the other to provide smoke stopping capabilities.

[Willo]

I know that for doors with strips and seals 3mm +/-  1mm is considered will fitting but is 3mm still considered well fitting for a door without strips and seals but with the larger rebate?

Another question, why 3mm? Because it is reasonable to expect that an adequately made and regularly used doorset can achieve this and to expect a tighter fit would be unreasonable? I suppose the curved path taken by the leading edge as the door rotates also prevents a tight fit. Or because it stops the larger smoke particles getting through?

[Fishy]

Door stop size does not make a significant difference to the fire resistance rating of a timber doorset

I would agree if the doorset was fitted with intumescent strip and the 12mm stop would most probably more effective. But to make these comparisons you would have to see the doorsets tested without intumescent strips was this the case?

If so you must be an old git like me.

Door stop size does not make any difference to the smoke sealing ability of a timber doorset (TRADA did some research that demonstrated this, I seem to recall)

I would be very interested in this research do you have any further details? I would like to know the amount of leakage to determine the threat to a means of escape?

Yes - not an old git, but a git nonetheless.  Seen them tested without the intumescent strips & they do around 15 mins, depending upon construction & fitting.  You can intuitively conceive that the size of the door stop will make no significant difference if the fire is on the opening side of the door, and this is borne out by 'real' tests.

Playing devil's advocate here, would you not agree intumescent strips are really for property protection, rather than life safety (other than in premises where there is a stay put policy)

Disagree, I'm afraid.  The only reason that we have them is that they are required so that timber doorsets meet the fire resistance performance referred to in the National guidance to the Building Regulations (e.g. the ADB in England & Wales).  These Regulations have nothing to do with property protection - only life safety.

[Indiana]

MidlandLion - what's wrong with property protection if you're a responsible building owner and employer?   Can't lay hands on the stats. like you guys, but I know that a significant proportion of businesses which have been involved in a fire never recover, and that's good enough reason for me.

Hiya Auntie Lin - always good to see you - you must pop in more often !!!

I certainly dont disagree with you, and yes building protection is an important consideration, I was debating the point however that intumescent strips aren't provided generally for life safety reasons (except buildings with defend in place strategies)

I assume that you are assuming that people will evacuate immediately upon hearing an alarm. This may not necessarily be the case though, especially in sleeping risks like hotels.