Examination of Witnesses (Questions 3300
- 3319)
3300. LORD YOUNG OF NORWOOD GREEN: I
am trying to get my head round your survey as being described
as a "second gear estate agent's survey"! Presumably
Alan Baxter, the expert you rely on, said that the survey you
have conducted was suitable and appropriate in the circumstances;
but some of the things that appear to have been missed, even if
we put to one side the internal surveys, there were comments that
were made about the height of buildings and whether there were
attics or not?
(Mr Berryman) First of all, I would not accept the comment
about the height of the building. That is not quite true, I accept
the comment that the building is the height stated; but the crucial
thing for us is the height of the masonry, not the height of the
building overall. On the scale plan that was shown, although I
am happy to accept the building is well over 15 metres tall, the
masonry is about ten metres tall.
3301. MR MOULD: Has that dealt with your
Lordship's point? I was going to ask Mr Berryman if he could take
this particular aspect a little further.
3302. LORD YOUNG OF NORWOOD GREEN: The
point I have been trying to make is about the quality of this
survey; because the generic allegation being made is, quite frankly,
that they are substandard and do not really meet the undertaking.
You have part answered it by saying you are going to come back
and do a more detailed survey; but I still worry a little bit
that you have based assumption on this. What I want to be sure
about, and probably my colleagues do as well, is the quality of
this. Does the survey you have conducted meet the requirements
at this point in your operation?
(Mr Berryman) My Lord, I can only reiterate the point I made
earlier that Alan Baxter is without doubt the leading expert in
the country on this matter. I think the Petitioner alluded to
that point in his evidence and expressed relief that we had employed
Alan Baxter. All I can say is I rely heavily on his advice, and
this is his advice, that this is the level of survey that is appropriate
for this stage of the works.
3303. BARONESS FOOKES: Would there be
confusion over the stages, in that case? This is not the final
stage—it is an interim stage and is appropriate for that
stage, with more detailed surveys coming later?
(Mr Berryman) Absolutely right, my Lady; I could not have
put it any better.
3304. MR MOULD: Mr Berryman, I wonder
if we can illustrate this a little more with reference to one
of the examples. You will recall that Mr Wheeler spent a little
time dealing with 17-25 Wilkes Street, and that is on the screen
in front of us now. This is the Alan Baxter Associates historic
buildings and features aspect of the Phase 3 report. The height
there you see at the top of the page is expressed as three storeys,
plus cellars, plus weavers' attics to numbers 19, 23 and 25?
(Mr Berryman) Yes, I see that.
3305. If we could just turn on to page 14, this
rather attractive drawing of the frontage of one those properties,
do you see that?[33]
(Mr Berryman) Yes.
3306. We can see the three storeys there, can
we, to parapet height?
(Mr Berryman) Yes.
3307. Then the attic structure on top?
(Mr Berryman) Yes.
3308. And the cellars we can see shown in outline
below?
(Mr Berryman) Yes.
3309. If we then come back, please, to page
11 and we see the engineering aspect, we have moved away now from
Mr Baxter and we have now come on to Mott MacDonald, have we not?[34]
(Mr Berryman) That is correct.
3310. We see the approach they have taken; in
the general description of the property they say "three story
brickwork terrace with basement and loft conversion", and
we have seen that in the drawing we have just looked at?
(Mr Berryman) Yes.
3311. "The structure is approximately"
and then various dimensions are given and the height is given
as ten metres. What is the significance of the reference to "the
structure"? Why is that important?
(Mr Berryman) As Professor Mair explained during his presentation,
the movement a building experiences is expressed as "strain".[35]
If you imagine a tall building which is subject to a hogging bending
moment so that it tends to do that (indicating), the taller the
building the more the strain, so the height of the masonry elements
is important in assessing what the strain will be at the top of
the building. Similarly when a building is in a trough and doing
that (indicating) the height is also important because it is the
dimension from there (indicating) to there (indicating) which
sets how big that strain will be.
3312. You referred I think to "hogging".
Just so I am clear, to the lay person is that the same thing as
tensile strain?
(Mr Berryman) Hogging is bending that way (indicating), and
sagging is bending that way (indicating). It is hard to explain
without a ruler.
3313. LORD YOUNG OF NORWOOD GREEN: Convex
and concave.
(Mr Berryman) Convex and concave. Thank you, my Lord.
3314. MR MOULD: Where does the concept
of tensile strain come in?
(Mr Berryman) Tensile strain comes in at the top of a hogging
or a convex bending. The top of the building will be under tensile
strain in that situation.
3315. If we go down the page we have the general
description. You have commented on the significance of the reference
to the masonry structure, and then we come down to the building
response findings; maximum settlement which Mr Wheeler referred
to, 26mm in this case; maximum ground slope; and then maximum
tensile strain and we see a percentage figure is given there?
(Mr Berryman) Yes.
3316. When we look at the classification of
damage table we can see that it is expressed by reference to limiting
tensile strains?
(Mr Berryman) That is right.
3317. Can you help the Committee with why the
classification of damage table is expressed by reference to that
consideration?
(Mr Berryman) The damage to elements of a building, particularly
a masonry structure but actually buildings in general, is almost
always a result of tensile stresses developing. Those tensile
stresses are as a result of tensile strains. The fact that the
bricks try to move apart at the top of the building is a strain,
but that puts a stress on the masonry structure. I am an engineer
and it is hard to explain without doing sketches, I am afraid.
That puts a stress on the structure. It is those stresses which
lead to cracks in the buildings. Those cracks are almost always
what cause any kind of damage, whether it is to the external features
or the internal features of a building. Things like stucco plaster
and so on, which have been referred to previously, if the building
itself cracks they would tend to crack as well.
3318. We can see that in the case of this building
in relation to that factor, that is to say tensile strain, the
classification of damage based on the engineer's assessment having
regard to Mr Baxter's historic buildings assessment, is within
the negligible category?
(Mr Berryman) It is. I think you can see the negligible category
goes up to 0.05 per cent strain. The strain in this building is
0.024 per cent, which is about half the limiting tensile strains.
I just want to emphasise, as Professor Mair said, that these assumptions
are very, very conservative. They are more than double the actual
results which have been achieved, for example, on the Channel
Tunnel rail link. We would expect this to be very much an upper
bound of the potential strain that may result. I would forecast
it would probably be about half that in reality.
3319. LORD YOUNG OF NORWOOD GREEN: For
that type of building?
(Mr Berryman) The type of building does not make any difference,
my Lord. The strain that is developed is a function of the ground
movement and the way the ground moves.
33 Committee Ref: A19, Scale drawing of 21 Wilkes
Street, London E1 (TOWHLB-20_05-014) Back
34
Committee Ref: A19, 17-25 Wilkes Street, Listed Building Assessments,
General Description, Mott MacDonald (TOWHLB-20_05-011) Back
35
Crossrail Ref: P6, Assessment-Deformation Types, Professor Robert
Mair, 20 February 2008 (LINEWD-RJM01-036) Back
| 
