Spread of flame

[lyledunn]

I was looking after the entertainment licence application of a small pub which underwent complete refurbishment. The works comprised the fixing of rough-sawn timber to most of the walls. Although I have been led to believe that SOF inhibitors have been applied, I have serious doubts. The evidence is nothing other than an invoice from the supplier and a statement from the painter that he applied the product to specification, although he could not produce or explain the specification.
Any way, the question that I wanted to ask was really about the implications if the timber wasn't actually treated. Firstly whilst the pub is small, perhaps 60 on ground floor and 20 in darts room on first floor the wall area is of an extent that SOF is required by Building Control. MOE is simple with most parts being no further than a few paces. I cannot see that the cladding would have much of an impact on life safety of customers and staff but may contribute to growth and spread which might be an issue for firefighters.

[Fishy]

Firstly, it's important to understand what spread-of-flame isn't... it's not  a means of measuring how fast a fire will spread across a wall/ceiling.  The BS standards essentially represent how much energy you have to 'pump' into that material in order that it exhibits sustained self-piloted flaming, & the BS EN tests represent how much energy the lining releases if a small-ish fire impinges directly on it.  The BS tests do this using a gas-fired radiant panel (Class' 1 - 4) and a small electrical 'furnace' (Class '0').  The BS ENs use a rather larger piece of kit that's meant to represent a waste paper-basket sized fire burning and directly impinging upon the surface (and it measures the 'power' output of the burning surface using a calorimeter).

I'd assume that untreated rough-sawn timber might achieve Class '4' if tested to the BS or Class D/E in the BS/EN (which is a about as bad as a building product gets).  This is not necessarily a problem if a fire will be detected early, if there will be no delay before evacuation commences, if the area in question can be cleared quickly (to a protected route or a place of safety), if the cladding is not on the means of escape routes and if there are no significant dead-ends.  If these cannot be achieved, though, I'd suggest that there could be a problem (let's not forget how many tragic incidents there have been where drinking/entertainment establishments have had fires where the wall/ceiling finishes have been major contributors to multiple deaths).

If you are worried that the stuff hadn't been treated, then you could recommend that a sample of the timber is removed and subjected to an 'indicative' test to BS 476: Part 7.  It's not expensive and it's a good indication that the stuff's been treated effectively.  I did this once for some scaffolding board (on a construction site) and it revealed that supposedly Class '0' marked treated timber was actually Class 4!

[Tom Sutton]

I understood BS 476 part 6 is the propagation test and is used to determine Class O which is an invention of the Building Regulations and nothing to do with British Standards. BS 476 part7 the spread of flame test and does measure how far a flame will spread across the sample, the results are given in four classes with class 4 being, any spread greater than class 3, class 1 being the lowest spread. If this is a misconception then I need to research it.

As to the OP an important consideration is how the timber is fixed to the walls, if they have used battens then it's more than likely to be class 4, I have found to meet the higher standards it needs fixing direct to the wall.

[Fishy]

I understood BS 476 part 6 is the propagation test and is used to determine Class O which is an invention of the Building Regulations and nothing to do with British Standards. BS 476 part7 the spread of flame test and does measure how far a flame will spread across the sample, the results are given in four classes with class 4 being, any spread greater than class 3, class 1 being the lowest spread. If this is a misconception then I need to research it.

As to the OP an important consideration is how the timber is fixed to the walls, if they have used battens then it's more than likely to be class 4, I have found to meet the higher standards it needs fixing direct to the wall.

Not quite... Class 0 is (as you say) defined in the AD-B / BS 9999 as being Class 1 to BS 476: Part 7 and a certain level of performance to BS 476: Part 6 (involving little 'i's and big 'I's...).  So, both tests are BS but it's only the guidance to the regulations that defines how you bring the results together to demonstrate Class 0.

If the timber is reasonably thick then I wouldn't think that battens / no battens will make any difference at all under the old BS tests.  The 'rough sawn' nature of the surface might, though.  The BS ENs are a bit different, though as if you get complete burn-through to the backside of the timber you'll have two surfaces burning instead of one.

[lyledunn]

I very much take your point Fishy about the contribution linings made in the many tragic fires that have taken place in entertainment venues. As I mentioned in another thread, my daughter lives in Bucharest where such a situation contributed to the deaths of 69 young folk. The political ramifications are still very much bubbling in Romania.
This is why I am loathe to dismiss the concern even acknowledging that the building could be quickly evacuated and the actual risk might be perceived to be relatively low.
How is certification normally provided to indicate that appropriate SOF has been applied?

[Mike Buckley]

With regard to the certification, I would normally expect a person who does this type of work to be accredited to FIRAS or another of the certification bodies. On completion of the work they would then be able to provide a certificate to show that the work has been carried out to a set standard. Whist I would agree that some of these schemes may be a bit toothless, at least the person accredited to it has had to jump through a series of hoops to get the accreditation. In my view a letter from the painter is not worth the paper it is written on unless it shows they are accredited.

As far as the other part of the problem goes, it would depend on what hat you are wearing. If you are looking at it as a Fire Risk Assessor, the issue would be the safety of relevant persons. If there is a fire, can everybody get out? Will the treatment or lack of treatment to the timber affect this? By the sound of your description it does not appear to be an overly big or complex premises and the occupancy is such that everyone would be able to self evacuate, so the issue of danger to firefighters would not be too much of a problem.

If you are wearing a Building Control hat, then if the regs state that SOF treatment is required then you need more evidence than a letter from the painter.

[Fishy]

With regard to the certification, I would normally expect a person who does this type of work to be accredited to FIRAS or another of the certification bodies.

Unfortunately, neither FIRAS nor the LPCB have schemes to cover this particular type of work, so that wouldn't be relevant.

For those that are interested, the ASFP's 'Orange Book' is worth a browse, as this pretty much explains what you ought to be looking for: http://asfp.associationhouse.org.uk/default.php?cmd=210&doc_category=222