techniques: one involving a factory. complex. the other an on-site adaptation. This exercise led to close consideration being given to the two, and it seemed that the problems of obtaining a site large enough for a factory, the difficulties of transporting large components around our some- times narrow and always congested streets, and the space readily available on the Authority's sites all pointed to on-site manufacture.
The other point is more technical. The process employed in Japan for the surface finishing of the panels is to start the steam-curing immediately the panel is cast in its mould, then to open up the beds after a short interval of time and trowel, float, or other- wise apply the finish and then con- tinue to cure. In the Hong Kong summer temperatures and humidity this was not possible and it was found that the surface had "skinned" too quickly so that hair cracks and other blemishes resulted.
With experiment, however, it was found possible to lightly trowel the surface before steam-curing com- menced and although the surface finish of the panels is not as good as we would have liked, it was good enough for low cost housing, at any rate. But here is where improve- ments are required; it should be the aim to get a better finish; as good as is obtained in Japan.
men were
The question of time was in this case not of paramount importance as it was more useful to find out how the system worked rather than how fast the system could work. In addition, the local semi-skilled work- not experienced in the early stage although they seemed to pick up the routine work very quickly. Being the first scheme of this kind, it took a comparatively long time at the preparatory stage but about half way through the work, the progress improved noticeably. Had the ex- periment continued or extended, there is no doubt the speed of construction would have increased and the increase could have been maintained.
The quality control was excellent as should be expected from most of the prefabricated systems. Inspection of work was made easier by the con- centrated working area, e.g. steel bender, concretor and the assembling gang worked in an area where it could be observed and controlled fairly easily. Incidentally, it was found that the bar bending could be done far faster than was required by the
panel makers, the pattern of bending being very highly standardis- ed. Thus, the bar bending team were able to do their work, put it into storage, and move on to the next job a very great economy being ef- fected.
The method of mixing concrete and casting, steam-curing, hoisting and assembling is always consistent and a standard of quality once established,
can be maintained without much difficulty. A casual inspection or spot check along the production line pro- duced better results than a horde of foremen being employed for the traditional methods of construction.
Costs
the
It was understood from beginning that a scheme of this size was not economical for prefabrication but it was considered large enough as an experiment, and the constractor was well aware of the situation when he made the offer. As expected the capital outlay for machinery and plant, totalling just over HK$800,000 was found to be far in excess of the requirement and the operational cost was high in comparison with produc- tion.
In fact the plant could have coped with a scheme four or five times this size, and the capital outlay would In not have increased very much. hard cash the contractor certainly lost money, and the Authority got its flats at a similar cost per person usual yardstick scheme.
―
our
as for any other
But Goodman received HK$1.22m. for a job which cost them, excluding fees, $1.47m. They had, at the end of it all, a reservoir of trained labour, a pool of plant about 12 per cent. of which was paid for on this job, and the know-how of techniques, cost control and site organization which enabled them later to land a HK$12m. P.W.D. Resettlement building con-
tract.
The final actual cost of the project to the contractor is given in the table below.
Cost to Contractor
(i) Nett expenditure incurred in respect of labour and materials
3.
HKS
HK$
1,000,953.05
56,417.00
1.
Nett cost of purchasing materials and employing labour directly
2.
Salaries of supervisory staff
Nett cost of necessary temporary works such as site office, storage sheds etc.
57,693.89
Less Agreed amount for the value
of residual materials
15,000.00
42,693.89
4.
Nett cost of premiums for insurance
covers
15,412.05
5.
Nett amount for the supply of metal windows, doors and louvres by Nominated Supplier
6.
Nett amount of Sub-Contracts:-
(b)
(a) Plumbing by Lee Yu Kee Ltd. Electrical Installation by Ellipo
96,359.84
Ltd.
32,117.86
(c)
Roofing by Precast Products Ltd.
31,545.08
160,022.78
$1,332,232.57
56,733.80
(ii) Nett cost of the use of all the mechanical and non-mechanical plant
(a) Agreed amount for the use of all the
heavy mechanical plant
(b) Nett cost for the use of all other mechanical and non-mechanical plant including scaffolding, formwork etc. Less Agreed amount for the value of
residual materials
HK$
44,252.42
HK$
100,500.00
10,000.00
34,252.42
$1,466,984.99
36
Far East Architect & Builder February, 1968
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