46.- Design and Construction of a Nineteen-Storey Load-bearing
Brick Building
by B. A. HASELTlNE and Y. T. Av
Jenkins & Potter, COl1sulting Engineers, London, WCl
A BSTRACT
Etude et Construction d'un Bâtiment
The circumstances leading up 10 lhe
decision 10 use bricklVork for a
large hOllsing scheme aI PortsdolVl1,
Hampsh ire are described. The scheme
ifle/udes filteen- , seventeen- and nine-
en Briques Porleuses de 19 Elages
L'arlic!e décrit les circonstances qui
conduil à décider d 'uliliser la
maçollllerie en briques pour le pro0111
jel d'un grand ensemble à PorlsdolVn,
teen-storey !ower blocks, of which
Hampshire. Ce projet comprend des-
tltirteen, fifteen and seven/een storeys
respective/y are constructed in loadbearing brickwork. There is Gn
associa/ed low-rise del'elopmelll of
fOllr-, six- and eight-Slorey /oad-
10llrs de 15,17 et 19 élages dont 13,
15 el 17 é/ages sonl construites
eering desigll of lhe nineteen-storey
compJetement en maçonnerie en
briques porteuse. Y son l associées des
contructions en briques porleuse d'une
dimellsioll 1110;I1S élel'ée, de 4, 6 el 8
étages. L'élude technique de la lour de
block is described alui lhe brickwork
strengths are given , (oge/l1er \Vi/h
011 ou/fine Df lhe specificatioll lIsed.
de la maçonnerie en briqlles S0111 dOI1nées ains; qu' 1111 aperçu du cohier des
bearillg brick bllildillgs. The engin-
The early COl1struction difficulties
and teclmiques are indicated. The
paper ;s iIIuslraled \Vilh diagrams,
plalls alui pholographs of lhe bllilding.
19 élages esl décrile et les résislances
charges.
Les premieres
difficullés
techniques de cOllstruction sonl indiquées. L'arlic!e est i11l1stré par des
diagrammes, tles plans, el des pll%graphies des bálimenls.
J. INTRODUCTION
In 1965, lhe City of Portsmouth held an architectural
competition for the design of a complex housiog scheme
on a mosl impressive 20-acre site aI the foot of Portsdown
Hill. The high part of the site commands magnificent
views over Portsmouth and the Solent to the Isle of
Wight, a nd , conversely, lhe sile is visible over a large
distance. The clients, therefore, were anxious that the
development would enhance, rathe r Ihan spoil lhe
scenery. The competition drew entries from ninety-one
compelitors, but lhe assessors were satisfied Ihat the
outstand ing scheme was ooe visualized from the outset
in brickwork, submitted by Theakston & Duel!.
The successful architects incorporated 523 dwellings
in their plan (Figure I), in addition to licensed premises,
shops, tenants' meeting hall, play area and 67 1 parldng
spaces (260 under cover). In order to discourage future
development spilling up the hill behind the sile, the
architects created a wall along lhe top of the site, with a
line of six- and eight-slorey maisoneltes, pierced by
si milar poinl blocks fifteen, seventeen and nineteen
storeys high. As the slope of the si te fa lls away there
are two more parallel rows of dwellings, firstly fourstorey rnaisonettes, and then two-storey houses. A
number of one-storey old persons' homes complete the
layout.
282
Entwurf und A usführung eines
neunzelrnstockigen Gebaudes aus lasttl'agenden Ziegelmallel·n
Die Zll der Entscheidung, Ziegelmauerwerkfiir eillen grossen Wohnbezirk in Por tsdown , Hampshire za
I'erwenden , führellden Umstõnde sind
beschriebel1. Im Wollllbez;rk srehell
Wohnhochhiiuser mil 15, 17 IInd 19
Slockwerken, 1'011 denen 13, 15 bzw.
17 Stockwerke aus (ragendem Ziegelmauenverk erstel!l wurdell. Dami/
verbullden ;sl d;e Enlwickhmg von
4-, 6- und 8-slõckigen Gebiiuden mit
tragendem Ziegelmauerwerk. Der
Ballplan des 19 Slockwerke hohel1
Blocks ist beschrieben. Zusammen mil
einem Oberblick der Giitel'Orschriften
Shld die Mallerwerksfesligkeitel1 al1-
gegebell. Auf die früheren KOl1slrukliOlls-Sclllvierigkeiten und -Tecllllikel1
wird hingewiesell. Der AlIfsatz ist mil
graphischen Darstellungen , Planen
und Plzolographien des Gebiiudes
l'ersehel1.
2. CHOICE OF STRUCTURE
The architects always envisaged a brick-faced scheme,
as this, they believed, was the on ly way of meeting the
competitian brief, which was to reduce ma intenaDce
costs to the Council to a rninirnum, consistent with
architectural quality a nd suitability to lhe importance
of the site. At the same time, it appeared that the use of
brick for the vertical slructure as well would prove
economical. Studies were carried out by Jenkins &
Potter on the following structural systems, afler it had
already been decided that no fully ind ustria lized system
could be used without altering the scheme so much that
the original concept wo uld be lost.
( I) 111 siru concrete wall structure.
(2) Battery-cast precast wall structure.
(3) Load-bearing brickwork, wilh il1 silll concrele
floors.
The quanlity surveyors, Davis Belfield & Everest,
costed the various schemes and came to the conclusion
that No. 3 (Ioad-bearing brickwork) was definitely lhe
cheapest. At the time that a decision had to be made, it
was Ministry of Housing & Local Government policy
to encourage the maximum use af in dustrializeti-building
techniques, and so me opposition was met before brick-
283
B. A. Haseltine and Y. T. Au
A Fifteen·storey block
8 Seventeen -storey block
C Nineteen-storey block
O Eight-storey wall blocks
E Six-storey wall blocks
F Four - storey maison ette blocks
G Four-storey maisonette blocks
H Two-storey split-Ievel terrace houses
I
One-storey old peoples' dwellings
Total dwelling units: 523
Total covered parking: 260
Total ope" parking : 411
Total parking: 671 (1 ·26 spaces per dweHing)
Ucensed premises with three-bedroom
maisonette
e
Supermarket with three-bedroom maisonette
Shops with three -bedroom maisonette
Tenants' meeting hal!
Five activity areas, covering seventy parking
spaces
9
h
Shopping square, covering th irty parking spaces
and stm8ge space
Community sQuare
Redirected pu
FIGURE l- Site layout.
work was finally chosen. Naturally, as much rationalization as possible was aimed at in the design of the
brickwork and the internaI work. It was interesting to
notethat slightlyfewer site men wereforecast to be required
by the quantity surveyor in their exercise for the loadbearing brickwork scheme than would have been needed
for the precas! battery system!
3. DESIGN FEATURES OF THE NINETEEN-STOREY
BLOCK
Although there are many interesting points which could
be made about the design of the whole scheme, this
paper is concerned primarily with the nineteen-storey
block, of which seventeen storeys are in load-bearing
brickwork. Jt is believed to be the tallest load·bearing
brick structure in the U K. The structure of the fifteenand seventeen-storey blocks is similar to that of the
nineteen-starey ane, and a plan is shown in Figure 2.
I! could be said that the layout of load-bearing walls
is not ideal for a structure seventeen storeys high,
because, although Ibere are enough walls to carry the
verlical load, there are a lot of openings which reduce
the effectiveness of the wa lls in resisting wind. Hawever,
by making use of the composite action of brickwork,
reinforced-concrele floors and special bcams, it proved
possible lo give lhe archilecl lhe plan he wanled while
achieving an economical structure.
.R
'1
~~~~9F~~
•
LR
•
•
LR
FIGURE 2- Typical f100r plan.
"
284
Design and Construction of a Nineteen-Storey Load-bearing Brick Building
3.1 Walls
The site at Portsdown is extremely exposed and, apart
from the wind problem, described in Section 3.3, the
design team were concerned that driving rain might
penetrate a normal cavily wall. After cost and design
exercises it was decided to use 9-in. externaI walls , with
the fio ar slabs expressed on the outside, and lO form a
cavity by erecting a Iight inner skin of blockwork
carried as a partition load on lhe floor slab, as shown in
Figure 3, Seclion B-B. In this way less water should
reach the cavily as lhe rain has lo penelrate a solid 9-in.
wall before reaching it. Normal cavily-wall dampproaf courses were provided at each ficor leveI. This
arrangement of walls was structurally as good as a
cavity wall 4t in.- 2 in .-9 in. and was cheaper, whilst
giving a better weather and thermal resistance.
.~
.~
BI
iI
I!!!!!!!l!!
.J
.J
li! l!m!!!
·{[trPs13
...
,'pie...
ELEv,.,TION AT WlNtlOW OPENING
/~
." /~ /
.'
" .m I
.~
[mo
9-in. Southwater Class 10
5th to 7th
9·in. Holbrook perforated seconds
7th to 9th
7-in. Calculon
7-in. Calculon
7~in. Calculon
9th to 12th
12th to Toof
against wind forces is to distribute the total overturning
momenl on the building between the individual walls ar
wall complexes in proportion to their stiffness. With so
many openings in the load-bearing walls, this would
have led to high uplifts at the windward end of lhe walls,
concrete. By usiog a stee! section , lhe architect's requirement for true-storey-height slot windows was achieved,
in certain cases, mainly for architectural reasons, 9-in.
1st to 5th
had
which was used lo design the unifying beams. The shear
forces so formed tended to be large and called for special
consideralion. Figure 3, Section A- A, shows the solution, which was to use a fabricated sleel seclion, capable
of taking the shear and bending forces when cased in
load-bearing walls are also provided. Table I gives lhe
variation of brick slrenglh wilh height for a lypical wall.
Type 01 brick
NEWBERRy3
at lhe posi tion of lhe openings was assessed from con~
ventional formulae, and this was translated into a force,
The internaI walls are 7-in . wide where possible, bUI
F/oor
and
strong complex shapes were achieved. The verlical shear
FIGURE 3- $hcar linking beam details.
FIGURE
SCR UTON
one loog one. ln conjunction with returo ends, very
~~
X,
However, a paper by
been published, and, after discussion wilh the Building
Research Station , a peak pressure of 36-4lbf/ft' at
the top of the building, dropping to 24lbf/in' at the
bottom, was selected for the structural designo Had
exposure D of CP3, Chapler V, been used , the pressure
would have been 29 Ibf/ft'.
The normal practice for lhe design of brick buildings
to enable several short ones lo behave as if they were
~ ' lIlOCK
~
BRICK STRENGTH (WALL
3.3. Wind
At the time the Porlsdown scheme was being designed,
British Standard Code of Practice CP3, (Chapter V)'
was lhe recognized code for calculating wind pressure.
and unacceptable compressive stresses in the leeward
end. It was, therefore, necessary to unite certain walls
,.,
TABLE I -
provided across ali the spans. To reduce the possibility
of excessive thermal horizontal movements of the floor
slab, possibly causing damage lo lhe externaI walls, and
to reduce the possibility of cracking belween heated and
unheated areas, lhe screed only was used for storage,
and a i-in. layer of polystyrene was placed between lhe
screed and reinforced slab.
2)
Streugth
(lbflin' l
10000
7 SOO
10000
7 SOO
S 000
3.2 Floors
In a lall brick building, the fioors play an imporiam part
in dislribuling horizontal forces from wall to wall and
in balancing up minor eccentricities of construction. In
this building the slabs were 7·in. reinforced concrele.
Underftoor heating is being used, and, beca use of a
previous investigation,l great care was exercised in the
slab design to minimize the deflection. Top steel was
and lhe design slresses in lhe brickwork were brought
down to acceptable leveis.
3.4 Accidental Damage
Ronan Painl exploded on the slructural engineering
scene when Portsdown was already well under way, but
before the brickwork of lhe three tower blocks had
slarted. While the layout could be lermed complex in
relation to lhe Institution of Structural Engineers'
Guidance Notes,' which were published much later, it
seemed prudent to examine lhe structure from lhe paiOl
af view that a main load-bearing walI rnight be removed
by accidenl, but that in situ floor sl.bs, particularly
with extra top steel, could be expecled to cantilever
compositely with brickwork, ar span across enlargetl
openings wilhoul actually failing in the full sense of the
word. There is obviously no requirement that a damaged
building should still be fil for habitation, only that it
does not collapse. Accordingly, it appears thal the loss
of any one wall , excepl the two unbuttressed externaI
walls, I and 2 on Figure 2, would nol resul! in collapse.
The absence of any worthwhile retum on walls I and 2
meanl that lhey could be more susceptible to damage,
and that no carne r pier would rema in to help carry load
from above in lhe event of a serious explosion. To overcome this problem , steel hangers have been incorporated ,
285
B. A. Haseltine and Y. T. Au
TABLE 2-TYPICAL REsULTIl OF BRTCK TESTS TO
as shown in Figure 4, east into slots left in the briekwork.
In this way, if one of the free walIs were to be removed
Bríck
(an unlikely event, in view af the amount af venting
provided) the fioor above would be suspended in plaee
by its hanger and would aet with alI the other walIs and
slabs above to eantilever like a fiag from the rest of lhe
strueture. Such a 'slrueture' eannol easily be justified by
calculatian, but, for the time being, an engineer is still
allowed some freedom of judgement.
OAl,VANlSfO IiIlD InEL !.lR. " OIA.
TO
n.u
8TORfY HEICHT
UUu
;:
I " " DIA. MILO
STEEL AOO.
DRlllEO ANO
TAPPED IIOTH
B.S. 3921 6
Test result
(lbf1io' )
Design strength
(lbf1io' )
L.B.C. Fletton
3000
4100
Warnham Class 5
5000
6130
Holbrook perforated seconds
7500
I
8670
Southwater Class 10
10000
10 740
Southwater Class 12
12000
19000+
Calculon C
5000
S 220
Calculon B
7500
10920
Calculon A
10 000
11340
Holbrook perforated sandfaced
facing
10000
11 460
7500
7960
(NOS
r
:!-----,---
. ... .: ..
DIA. BAR
Nutborne Whitley facing
CONCRETE
I
INFILL
WIAE lOOP AT EACH BA leK COUASE
PlAN
c·c
FIGURE 4---Delail of steel hangers.
4. CONSTRUCTION
4.1 Specification
When load-bearing briekwork is used for talI struelures,
it is naturalIy essential that the speeifieation used should
4.3 Mortar
The model specification S requires a preliminary laboratory mortar strength at 28 days for a 1 :t:3 mortar
of 2700 lbf/in' and a site strength of 1800 lbf/ in'. Table
3 shows the results obtained by an independent laboratory
earrying out the preliminary tests for the contractor.
TABLE 3-PRELlMINARY LABORATORY MORTAR TEST RESULTS AT
28DAYS
Strength (lbfl in 1)
CQver ali the necessary points on materiais and work-
Tesr
No.
manship. The Portsdown bilIs of quantities were being
eompleted when the B.Ceram.R.A. model speeifieation s
was being prepared, and, with minar amendments to
alIow for the actual brieks being used on the site, this
I
draft specification was used, but without the section
dealing with 9 x 9 in. si te eubes of briekwork, as the
authors' experienee had previously shown these to be of
little value.
4.2 Bricks
The specification ealIs for samples of brieks to be tested
in aeeordanee with BS 3921 6 aI intervals as required
by the engineers. Load-bearing brieks for thi s projeet
\Vere being obtained from a manufacturer who main-
1:* : 3
2
3
-
4
5
-6
Remarks
Mi:<
--
--
Cube No.
Mortar
1:* : 3
Colour
mortar
J
2
3
2860
3010
2860
2360
2680
2490
2570
2440
2440
2360
2360
2240
2540
2840
2850
3110
27Jõ
2900
--
4
These results
were rejected
as there was
doubt about the
laboratory mixes.
3180 This set of cubes
was made on site.
The original intention of the contractor was to have
tains a high degree of quality contraI in his works, and
the number of tests earried out refieeted the confidence
placed in the quality-control processo AlI brick tests
one central weigh-batching plant where alI the morta r
for the whole projeet would be made, and this was used
were done on samples taken from the stocks waiting to
diffi1,;uIt lo distribute different coloured morlars and
be delivered to the si te, so that it is not necessary to ask
for brieks already delivered to the contract to be removed should a test fai!. In fact, no tests did fail and the
margin was generalIy high. Table 2 shows a seleetion of
results for load-bearing brieks used.
The stoeking and label!ing of different types of bricks
can cause difficulty on site unless they are physiealIy
different in appearance. This problem arose at Portsdown
in respect of Grade 4 and Grade 5 Warnhams, which
look alike and also the two higher grades of Calculon.
In the case of the Calculon, a paint stripe is used by
lhe manufaeturer to denote Grade 10, but identifieation
between the 4's and 5's became so difficult that, in the
end, the manufaeturer supplied alI 5's while only
charging for the bricks aetualIy ordered.
to start witb. However, it was found progressively more
different mixes over such a large site from Dne central
area and ensure that the mortar was stil! fresh. As a
result, several smalIer weigh-batching plants were seI
up serving each individual area. It should be noted tbat
to have ali the mortar weigb-batched is relatively unusual ,
even on a site where high load-bearing brick structures
are being buil!.
As a result of the problems of distributing mortar
from a central batching plant, some experiments were
carried out on site on the etfect of retempering mortar
when it had started to stiffen. Morlar cubes were taken
in three stages :
(a) from the fresh mortar as delivered to the spot
board.
286
Design and Construction of a Nineteen-Storey Load-bearing Brick Building
(b) when reconstituted, after the mortar had become
too stifffor use by the bricklayer; and
(c) when lhe mortar had been further reconstiluted
afler stage (b) had also become too stiff lo use.
Table 4 gives the results of the crushing tests on the
sets of 3 x 3 in. cubes, together with the specified works
strength. It can be seen that although retempering reduces
lhe slrength, lhe result of stage (c) was still within the
specification. This would not necessarily have been the
case, but for the fact that the sand used was particularly
suitable for making a good strength mortar. As the
strength became seriously reduced with prolonged
waiting, a time limit af I! h was set fram mixing to use
of mortar.
TABLE 4-RESULTS OF CRUSH ING TESTS QN 3 x 3 in. CUSES
1 :*:3 Colour mortar. Temperature: 21 ° 10 22°C. Humidity : 65 to
68 %. Specified work st rength : 1800 Ibf/in 2 •
Time after
illitialmixillg
(iI)
28~day
test reslIlts
(individllal cubes)
(lb//in')
t
2451
2364
2439
1st addition of water
I±
24 15
2376
2402
2nd addition of water
2
2203
2251
3rd addition af water
2t
2053
2053
Fresh mortar
4.4 Site Progress
The whole scheme at Portsdown is a large one, and the
nineteen-storey IOwer block forms only a part of it.
The contractor appears to have experienced some
difficulties in lhe deployment of labour and hence in
maintaining his overall programme, and the speed of
construction 00 the tower blocks has not been what was
anticipated. ln the original design conception, it was
assurned that the semi-nonloadbearing end waUs of
each flat box could be left out and pul in one tloor
behind the leveI of conslruction. This might have
enabled lable forms to be used inslead of conventional
formwork if lhe contraclOr had desired. However, the
successful tenderer chose not to adopt this rnethod and
resorled to normal formwork, compleling ali waUs
before commencing the formwork for one tloor. It is
not possible lO say whelher this had an adverse effect
on the progress, but, undoubtedly, the turn-round
has not been as high as has been achieved on olher tall
load-bearing brick buildings. Figure 5 shows the
progress of one of the tower blocks.
5. CONCLUSIONS
Portsdown Hill Housing Scheme is probably one of lhe
most important load-bearing brick schemes that has
FIGURE 5- 0ne af the tower blocks, showing building work in
progresso
the rigid cost requirements of the Ministry of Housing
& Local Government. Al lhe same time, the economy
afthe load-bearing brick structure has helped in releasing
funds for other desirable paris of the scheme.
ACKNOWLEDGEMENTS
The aUlhors are indebled to the architects, Mr E.
Theakston and M r J. D . Duell of Theakston & Duell,
and to Mr I. M. D. Potter, of Jenkins & Potter, who
were responsible for the development of lhe slruclural
design , for permission to present this paper.
1.
(4), 105, 1965.
Code af Basic Data for lhe
Design ofBuildings. C.P.3: 1952, Chaplcr V.
3. SCRUTON, C. and NEWBERRY, C. W., On the Estimation af
Wind Loads for Building and Structural Design. Proc.
2. BRiTlSH STANDARDS INSTITUTION,
I.C.E. 25, June , 1963.
4. I N5llTIfTION DF STRUCTURAL ENGINEERS, Structura( Stability
and the Prevcntion of Progressive Collapse. Circular
RP/68/01,December, 1968.
Spccificat ion
for Load-bcaring Brickwork. B.Ceram.R.A. Spec. Publ.
5. BRITISH CERAMIC R ESEARCH ASSOCIATION, Model
ever been undertaken in this country, or, indeed, any-
where in the world. The part which is completed indicates
that a very high standard of dweUing wiU result, despite
REFERENCES
M. and HASELTINE, B. A. ,
Investigation into lhe Causes af the Deflection af Hcaled
Concrete Floors, Including Shrinkage. SlrllCI. Ellgr. 43,
SEFTON J EN KfNS, R. A., PLOWMAN, J.
56. 1967.
6.
BRITISH STANDARDS INSTITUTION,
Brickearth. Clay Of Shale. B.S.
8ricks and Blocks of Fired
392 1:1969.