Door width variation

[lyledunn]

Bs 9999 2008 seems to have a different tack to the current 2017 version in that door width calculations have been subject to significant change. For example An 850mm door with a B2 risk profile allowed simple division by 4.1 to arrive at an allowable occupancy. The current version now states that for doors less than 1050mm the occupancy for the B2 profile is 500 divided by 4.1.
Does that mean that the 2008 version is an unreliable method?

[colin todd]

Yup.

[lyledunn]

Colin, as someone Who was involved in the writing of a British standard, can you advise me as to how I might ascertain the machinations behind this dramatic change. Is there a route that would get the matter addressed by those responsible for making the provision? For me it is a very worrying issue. I have been involved in persuading entertainment licensing authorities to increase occupancy levels at many venues based on the simple calculation in 9999 2008. I would be devastated if some tragedy occurred.

[colin todd]

Lyle, what can I tell you.  Back in 2008, at a two day BSI training session on the then new standard, a chum from LFB (God, did I just admit I have a chum in LFB-dont hold it against me too much), both of us being delegates and not the trainers, did some back of an envelope examples to show that the numbers were bonkers for narrower door widths.  In all courses I, myself, delivered, I pointed out the huge anomalies that could be created between ADB (or model terms for licensing in NI for that matter) and BS 9999.

Interestingly, the change you correctly highlighted (and which we highlight on all our BS 9999 training courses) is not even listed as a principal change in the Foreword to the new standard, but boy it does make a difference doesn't it.  Odd that it is buried away like that but then I am not a conspiracy theorist.

Write to BSI if you are unhappy or wish to demand an explanation.  The 2008 standard was poorly QA'd and was too long/not enough time given for people to bother to make public comment at the DPC stage.  So it got published.  Bad things are what happens when good people dont pay enough attention.

Sorry cant be more helpful.

[lyledunn]

Quite the contrary Colin, you have been vey helpful, many thanks.
The provision of exit width is often the single factor that determines occupant capacity in venues seeking an entertainment licence. We have licensing officers spitting teeth about the capacity of an 800mm door often requiring frames to be ripped out and door replaced all to gain an extra 50mm when in fact it probably makes not one jot of a difference.
I used 9999 2008 to good effect in presenting a case for existing licensed premises to increase occupant capacity, which was something highly desirable for commercial reasons. Often the application was reluctantly granted but granted nonetheless as 9999 2008 was an acceptable alternative reference. I have managed increase occupancy in perhaps 50 venues. Now I find this debacle! Gonna need some explaining!
I once had a yellow guide, I think I will dig it out again and stick to it.

[colin todd]

Lyle, do the model terms not deal with exit widths.  The old yellow guide used 2 minutes, 2.5 minutes and 3 minutes evacuation times.  You should maybe use the sector specific guides that support the FRS (NI ) Order.

[lyledunn]

I had a chat with a senior officer in HSE. He told me that it was perfectly reasonable for me to rely on the requirements and recommendations set out in a British Standard and that there was no need to "second-guess" any aspect of the document.
It does seem, however, that someone on the 9999 BSI committee has being doing a bit of second-guessing and has surreptitiously lifted the edge of the carpet!
Still, even with the new dispensation exit capacity for an 850mm door can be 151 using the enhanced approach, a lot better than the 110 allowed in Technical Booklet E. Might there be someone with a broom along in a few years time looking for space under the increasingly lumpy carpet?