PRECAST CONCRETE ELEMENTS DOMINATE IN NEW HOUSING PROJECT:

Everything, apart from the foundation platform, uses precast concrete. This includes the masonry, roofing, upper level flooring, paving, reticulation poles, kerb stones and sewer piping. Even staircases for the multi-storied units utilise precast concrete.

PZR is responsible for the planning, design and project management elements. Civil engineering consultancy, Bigen Africa, is handling the civil work design aspects, and Civtek cc is the main civil works contractor. The primary above-the-ground contractor is Sea Kay Engineering Services (Pty) Ltd., which boasts a CIDB rating of 8.

The project has been designed with three occupier categories in mind and, when completed, Pennyville will comprise 2 800 units in 36m², 40m² and 42m² variants, mainly as single-storey units, but also as double and triple storey units.

Approximately 1 400 houses will be allocated to qualifying RDP beneficiaries from the Zamamphile informal settlement. These houses form part of the Housing Council and National Housing Department’s commitment to housing development, and will be owned by the beneficiaries under sectional title.
 
One of the huge advantages of Pennyville is its close proximity to the centre of Johannesburg. Some 400 units will be owned by JOSHCO, for renting to people who already own a home elsewhere but require accommodation closer to their place of work. They will be given the option of either leasing whole units or individual rooms within three-bedroomed units, depending upon their requirements.

The remaining 1 000 units will be purchased by banks and will either be leased or sold to
owner-occupiers.
 
John Cairns, director of the Concrete Manufacturers Association (CMA), says that the dominance of precast concrete in the construction of Pennyville demonstrates emphatically its versatility and inherent quality.

“The use of diamond-faced concrete bricks, concrete roof tiles and concrete block paving on the paths between the houses, means the development will have an attractive homely appearance even before the establishment of gardens and the planting of trees,” notes Cairns.

The RDP and JOSHCO units will comprise a living area, a bathroom with a wash basin and toilet and pre-paid electricity. The RDP units are being built without ceilings or baths, the intention being to provide housing which can be upgraded as the prospects of the owner-occupiers improve. Owners who install baths and ceilings, and plaster the inner walls, will be able to qualify for a bank loan.
 
The project is being built in four phases, civil works having commenced towards the end of 2006. Phases one, two and three of the RDP and JOSHCO units will be completed by December and phase four will be completed by April next year. Occupation of the first completed units began in August.

The houses are being built on concrete platforms with steel-reinforced foundations, which are based on a Waffle Raft® design to prevent cracking in the event of soil heave or movement. Foundations are laid with 400 - 450mm edge beams to support the platforms, and concrete floors are cast to either 20 or 25 MPa, depending upon geotechnical conditions. After power floating they are left to cure under moist conditions for a week.

Masonry work entails using 10 MPa concrete Single Maxi Diamond-Faced bricks measuring 140mm x 290mm x 90mm, which are being supplied by Sedibeng Bricks in Meyerton.

“Diamond-faced bricks are an attractive alternative especially for this type of development where there are many houses of uniform shape and size in close proximity,” notes Cairns.

Prestressed hollow-core slabs manufactured by Echo Prestress according to specifications laid down by the project’s structural engineer, Victor Booth, are being used for the flooring of the double and triple storied units. Even the staircases are made of precast concrete and these are being supplied by Pre-Cast Staircase, as are the lintels and the prestressed beams.
 
Gary Clark, Sea Kay Engineering Service’s on-site project manager, says the use of prestressed hollow-core flooring means that masonry work can begin on the upper floors as soon as the flooring has been laid.

“This is saving at least a week’s construction time on each house. Similarly, the use of a precast concrete staircase also aids quicker construction times.

"Once the masonry work and roofing have been completed, the walls are bag-washed on the inner and outer surfaces. A good quality paint from Prominent Paints is then used on external walls, which together with the bag wash, ensures excellent water-proofing properties,” observes Clark.

Concrete roof tiles supplied by Lafarge Roofing are being laid on a low-cost steel truss system. A recent survey conducted on behalf of the CMA demonstrates that concrete roof tiles are the most cost-effective form of roofing on roofs built with trusses.

“They are also aesthetically pleasing, imbuing pride of ownership and enhancing the value of the houses on which they are used considerably,” says Cairns.

Concrete paving blocks for the pedestrian paths are being manufactured by Concor Technicrete, and prestressed concrete poles for overhead power supply cables were manufactured by Infraset Infrastructure Products. Approximately 1 000 poles in four sizes ranging from a 7m 4kN pole, to a 10m 8kNpole were installed by Kusokhanya Electrical Contractors.

Precast concrete kerbing is being supplied by Rand Kerbing, Blitz Beton and Concor Technicrete and the storm water pipes come from Cula and Infraset. Sewer manholes were supplied by Salberg.

Besides providing much needed additional housing, the Pennyville project has provided work to previously disadvantaged sub-contractors. They are sub-contracted to Sea Kay Engineering with the proviso that they are registered, have the requisite skills and are based in South Africa. Where necessary, Sea Kay is providing additional skills training in collaboration the National Home Builders Registration Council (NHBRC).

Prestressed hollow-core concrete slabs manufactured by Echo Prestress, shortly after being lowered into position on one of the double-storied housing units at Pennyville.

High-quality affordable housing, most of it built using precast concrete elements, predominate at Pennyville. The picture shows houses built with Sedibeng concrete bricks and roofed with Lafarge concrete tiles, a path paved with Concor Technicrete’s concrete blocks, and prestressed concrete poles manufactured by Infraset.

One of the houses at Pennyville which is being built with diamond-faced concrete bricks.

Precast concrete was used extensively at Pennyville and, as is shown here, included staircases supplied by Pre-Cast Staircase, on the multi-storied units.