Examination of Witnesses (Questions 85
- 99)
TUESDAY 20 JULY 1999
DR STEPHEN
LEDBETTER AND
MR CHRIS
BUNTAIN
Chairman
85. We can continue with the third session this
morning into the potential risk of fire spread in buildings via
external cladding systems. Gentlemen, can I welcome you to the
Committee and ask you to identify yourselves for the record?
(Dr Ledbetter) I am Dr Stephen Ledbetter from the
Centre for Window and Cladding Technology at Bath University.
(Mr Buntain) I am Chris Buntain. I am technical manager
of a company specialising in the development, manufacture and
installation of insulated cladding systems.
86. Thank you. Do either of you want to add
anything to what has been said so far?
(Mr Buntain) I think it is important from the outset
that we clarify what the situation is with regard to the Irvine
block. The Irvine block was not overclad. The Irvine block is
a block of concrete common throughout the whole of the United
Kingdom. It is made of concrete and it is as non-combustible perhaps
as you can get within the building industry. It certainly will
not catch fire. It was not overclad by any material at all. It
had had its windows replaced by the local authority using a plastic
window and it was the full height plastic window units within
the block at Irvine that caught fire and the panels below the
window, but not overcladding which the building is assumed to
have had by some people. It was not overclad. It had a composite
window unit which caught fire.
(Dr Ledbetter) There have been tests developed for
fire and there has been research into the behaviour of fire. It
has largely been by fire engineers and not by building engineers.
This misunderstanding of the type of cladding seems to be rife
amongst those developing tests. I would emphasise the point that
we need to be clear as to what types of construction cladding
we are discussing at any stage.
Mrs Ellman
87. What is your assessment of the risk of fire
in external cladding systems?
(Dr Ledbetter) My own assessment would be that there
are very few incidents that are known within the industry. Obviously,
not all incidents are reported back to the industry from the Fire
Brigade and from local authorities but we do always resort to
talking about one or two incidents which are notable, notable
because there are not very many I suspect, and notable because
of course in a high rise building there is a greater risk. It
may be a very rare event. It is the same if we get an accident
with an aircraft, where the intensity of the event is great but
the number of deaths is not that great compared with the number
of people generally killed in, say, road accidents. What we get
is a concentration of people's minds as to what could be a large
but rare event and I suspect that there are more people injured
and killed by fire in low rise buildings.
88. You think the dangers are exaggerated?
(Dr Ledbetter) If we see a fire in a high rise building,
we perceive that it might become a large fire. That is probably
more a matter of perception than reality. I am not aware of many
incidents of fire spreading through high rise buildings, particularly
through the cladding, by burning out and burning back in.
(Mr Buntain) Before any research is undertaken, we
should get a perspective on this thing in so far as the scale
of high rise incidents is concerned with regard to cladding installations.
Like Dr Ledbetter, I do not know of a great number of incidents
of fires which have taken place in multi- storeys or indeed in
any overclad buildings. I know of some but there are not very
many. I would suggest also that we should call on European experience
which is perhaps 20 times more in terms of the surface area of
buildings that are overclad with potentially fire reactive insulants.
We should have a look at Europe and find out what exactly the
scenario has been there and whether there have been situations
which have given rise to concern. For example, typically, the
German market is 20 times larger in overcladding terms than our
own United Kingdom market per annum. Therefore, their experience
is at least 20 times more than ours. The Germans also pay great
attention to detail in terms of the soundness and fitness of their
materials. They will test absolutely anything before it is assessed
as being fit to put on a wall and it would seem to me that it
would be appropriate to have a look at this German and continental
experience more widely to find out what the extent of the problem
is and how they are dealing with it and how they are addressing
it; and also to see whether there is any pending European legislation
coming about which might address this problem and some test procedures
which might come through the European technical lobbies which
might address this problem.
89. Are current regulations adequate?
(Dr Ledbetter) I believe that the current regulations
are adequate in as far as they can be. One of the problems with
regulation is that it is very difficult to be specific and write
regulations which embrace all forms of construction. There is
a very wide diversity of new construction and I believe that is
what we want as a country in terms of having a diverse cityscape
and diverse forms of architecture. It is more complicated with
overcladding where we go back to existing buildings and we overclad
them. Then we end up with an even greater diversity of forms of
construction. What we have done at the time being is write regulations
which generally embrace the intent of preventing the spread of
fire. We are looking at developing methods of test. To date, we
have developed methods of test that are specific to just two types
of building construction and not to all forms of building construction.
Therefore, to write tighter regulation would be difficult because
it would not embrace all the buildings that we currently construct.
(Mr Buntain) There has been some inference, if not
suggestion, that full scale fire tests have not been carried out
on fire reactive cladding systems in buildings. Some 10 or 12
years ago, a test was carried out at Cardington under the auspices
of the Building Research Establishment, albeit it was only to
a three storey structure at the time, but it was full scale and
it did have largely the types of cladding system which are predominant
in the field of overcladding, particularly on multi-storey buildings.
The fire tests were carried out and certain conclusions were drawn
by Building Research at that time relating specifically to fire
fixings which would restrain and retain the cladding on the wall
while the fire was being extinguished; and also to find out how
these systems reacted in a real fire situation. When I have a
look at the test equipment and the proposed test regime which
is now being suggested, I see many similarities to something which
did occur about 10 or 12 years ago. It is wrong to think that
we did not take fires seriously then. Those of us, including myself,
who are involved at the sharp end of designing and installing
these systems did have a Defects Action Sheet produced by Building
Research which we have incorporated into our high rise designs
ever since that fire test was carried out. It is not embodied
in law; it is a recommendation but most manufacturers put it in.
Fire stopping in multistoreys is something that is done in these
systems.
90. What could be done further now to minimise
the risk of fire damage in the situations you describe?
(Mr Buntain) Fire damage is not the problem. Nobody
is really interested in retaining the building. The building will
be damaged whether it is concrete, whether it has plastic windows
or whether it has polystyrene on its outside. It will be damaged
by fire. The fire authorities—I think they would agree—have
two prime concerns. One is the safety of those people escaping
from the fire and, secondly, those people who are fighting the
fire. If the building survives, well and good, but the main concern
is to get people away safely. If the building is, to a large extent,
non-combustible or highly fire resistant—and the two words
again should not be confused; you can get a material which is
non-combustible but it need not be fire resistant—it is
very significant in giving the fire authorities confidence to
fight that fire in the knowledge that the building is not exacerbating
the fire.
91. What could be done to secure that type of
building? More regulation? Different regulation? Something else?
(Dr Ledbetter) We currently have a position whereby
the industry has its own guidelines as to how it puts fire stopping
in cladding, how it uses materials that are not ignitable. The
respectable part of the industry obviously works in that way.
That is not to say that all of the industry does but most buildings
that are high rise are supervised in their construction or renovation
by professionals. Therefore, we do get that check from the professionals
involved in design. There is currently some confusion. We have
a number of methods of test being developed and to give guidance
on that at the time being or to embody it in regulation would
be difficult. We have a method of test developed by the Building
Research Establishment which is currently up for discussion as
a proposed British Standard. I was in receipt only yesterday of
documents from the European Technical Committee where the Germans
are requesting that a test be developed, a slightly different
test. We have also had a test developed by the insurers, by the
Loss Prevention Council, and all of these are different tests
and all of these tests relate to different forms of cladding.
I have personally been asked by all of these groups to advise
them on the forms of construction because they are essentially
fire engineers. I think there is a need for the constructors and
users to sit with the fire engineers and develop recognised tests
before we can advance with regulation. In the meantime, we have
to work on the best advice that we currently have and our lengthy
experience in this field.
Mrs Dunwoody
92. Why are you making this artificial distinction?
Why should your group be more accurate in their assessment, which
is what you seem to be implying?
(Dr Ledbetter) I am not suggesting that my group would
be more accurate in its assessment. I am suggesting that there
are different groups involved in this issue. There are some people
who understand fire and the spread of fire from largely traditional
forms of construction. What we have to understand is that the
method of cladding buildings has changed radically in the last
20 years, particularly so in the last 10, where we have developed
new systems of building. We need the manufacturers and developers
of those systems to sit with those who have been studying the
other aspects, such as fire, in a more traditional setting. We
need a cross-industry discussion between those developing tests,
those constructing and those developing yet further systems.
93. Are you saying that you are not fully represented
on the Ministry's committees and on its consultation documents?
(Dr Ledbetter) The way in which the tests have been
developed is for specific solutions to specific problems. Nobody
has actually looked at the problem in its generality.
94. So you do not discount the evidence that
we heard this morning; you are simply saying that it can be interpreted
in a different way?
(Dr Ledbetter) I apologise. I was unable to be here
for the earlier part of the proceedings. There have been tests
developed which look at specific forms of construction, not at
all forms of construction. We should make a determined effort
to sit down at industry, the test houses, the users and manufacturers,
and discuss this issue.
Mrs Ellman
95. Are you saying that this should be left
to the industry itself or certain sections of the industry?
(Dr Ledbetter) No. I am suggesting that we should
have the normal method of developing technical standards that
we use in this country. One method of test has just now been put
forward for discussion as a proposed British Standard and I for
one think it should be broadened to cover other forms of construction
so that it could then be used within regulation, if that is what
was desired.
96. Why would you say that fire spread so quickly
in Irvine, which you have mentioned, and in Knowsley in Coventry?
(Dr Ledbetter) Certainly in the case of Knowsley,
that was an older form of construction and there was, I believe,
inadequate fire stopping. We have learned the lessons of that
incident.
Chairman
97. Are you satisfied that fire stopping has
been put into all the tower blocks where it is needed?
(Dr Ledbetter) No, not at all. I am sorry if I have
misled you but I am talking about new forms of construction and
new forms of overcladding. I am not talking about the existing
housing stock which I think is a separate issue.
(Mr Buntain) I think this is something which will
impact on the future of building construction. I do not know whether
this Committee deals with it or not but insulation standards are
going to be very seriously looked at in terms of the increased
insulation standards to cut down CO2 emissions and get things
like affordable warmth and so on. With these insulation products
which will have to be used, many of them on the exterior of buildings,
the only place to put them probably, the whole question of the
fire issue is very important. Unless the means of protection which
are these fire barriers, which are recommended to be put in, are
put in or unless a non-combustible insulant is used, for example,
the building is at risk but that is not normally the case. Could
I suggest finally that perhaps legislation may not be the route
to go down because there are other things which regulate these
systems. There are things like the British Board of Agrement or
WIMLAS which are test bodies which do test these systems and which
do test for wholesomeness in systems for use in buildings. It
could be that the remit of Agrement or WIMLAS was extended to
cover the kind of testing that you are talking about, because
most people who are serious about being in the business of overcladding
buildings do get a WIMLAS certificate or a BBA certificate for
their product.
98. When we talk about public safety, is it
good enough to refer to what most people in the business think?
Do you not feel there should be better regulations?
(Dr Ledbetter) There is currently regulation which
sets out the intent that fire should not spread through cladding,
but it would be impossible, I believe, to write regulation which
would actually be applicable to all forms of construction because
we do not currently have agreed methods of test against which
we could prove all forms of product and construction. That is
the reality. Until we can develop those tests, it will be very
difficult to frame legislation.
Mr Cummings
99. This Committee may wish to recommend that
the draft British Standard resulting from the test devised by
the Partners in Technology programme at the Fire Research Station
become mandatory, at least for new cladding. What would your reaction
be to such a recommendation?
(Dr Ledbetter) I believe that the test has been developed
for a restricted form of cladding which is overcladding of buildings
containing small glazed areas within concrete or masonry walls.
There are many other forms of construction, notably curtain walling.
This is the kind of cladding which appears on hotels and a number
of residential blocks. I think any legislation which was framed
in terms of residential properties would have to cover a wider
variety of cladding systems.
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