Boon for city dwellers as Raubex completes Union Square

Boon for city dwellers as Raubex completes Union Square

Edited by Rory Macnamara

The renewal of Johannesburg’s city centre is getting a further boost with the expertise of Raubex Building, part of the Raubex Group’s infrastructure division.

Work was well underway on the refurbishment of Union Square, a 19-storey block at 80 Plein Street in the heart of Johannesburg’s original central business district. The project, scheduled for completion in the last quarter of 2020, is being undertaken for the Johannesburg Social Housing Company (JOSHCO), under principal agent and architect, Heather Dodd from Savage and Dodd Architects. According to Juan Jardim, Raubex Building’s senior site manager on this contract, the project involves several important innovations – and more than a few challenges.

“The building was previously an office block, and is being repurposed for residential use,” says Jardim. “This means the installation of considerably more walling and other infrastructure than the building was initially designed for.”

20200825 091740Plumbing ducts before closing up. Image credit: Simon Oliver

While the ground floor at street level will be used as retail space, the first floor to the 19th floor each accommodates 18 residential units. The range of apartments includes bachelor flats of 19m2 in size, one-bedroom units of 35m2, two-bedroom units measuring 43m2 and four-room communal cluster units of 94m2. The building is served by two passenger lifts, a service lift and a goods lift, as well as three fire staircases. There are three basements for parking.

20190912 095752 resized← The basement water booster pump feeding the roof tanks being installed. Image credit: Simon Oliver

The need to minimise the weight of additional infrastructure also affected the choice of water heating options. Union Square has a gas-heated boiler system on every fifth floor, which distributes hot water to the apartments. In addition to refurbishing and augmenting the inside of the block, Raubex Building also replaced the façades.

“This was necessary because of the ageing concrete on the outside of the structure, which meant that the original plaster and tiles were delaminating,” Jardim says. “About 5 000m2 of old plaster and tiles had to be broken from the face of the building, exposing the concrete. We could then break off loose concrete where necessary and clean the exposed reinforcing bar.”

So extensive was the outer decay that some 33 000ℓ of the specialised BASF MasterEmaco S 5410 CI, a fibre reinforced structural repair mortar with active corrosion inhibition, was used in the repair of the concrete structure. These repairs could then be followed by waterproofing, plastering and the applying of a Marmoran finish, as well as glass replacement and general painting.

20200124 094515 resizedThe pressure reducing valves to the hot water system and gas boilers. Image credit: Simon Oliver →

For its tenants, Union Square is conveniently located right across the road from the busy Noord Street taxi rank, which is among the largest in the country – serving local and international commuters. For Raubex Building, however, this location made for challenging logistics, especially as the property extends onto the sidewalk and street on every side, providing no lay-down area for materials and equipment.

“Most taxi activity would begin early in the morning and continue until 19:00,” Jardim says. “This meant that our deliveries were made mainly in the evenings. The night shift would then move the material to the floors where it was required, to facilitate the following day’s work.”

Material was conveyed using a two-tonne hoist that ran the full height of the building. Rubble was also removed at night, by tipper trucks fed by wheelie bins. He notes that the building’s first-floor plinth was just about the only space available to lay down materials and equipment.

“This project provided us with another opportunity to support local participation with the use of local labour and to train small local businesses, mainly in carpentry, specialised walling system installation, tiling, brickwork, plastering, painting and electrical work,” he says.

There were several of these businesses from Johannesburg’s Ward 59 involved, as part of Raubex Building’s local participation programme, and this included PC Builders, a 30% QSE partner on this project.

Plumbing Africa spoke with the Wet Services Engineer, Simon Oliver of Design One Consulting who provided this overview:

The age of the building and the change of use from office block to residential meant that none of the existing wet services were able to be reused, so were removed. New water and foul drainage needed to be installed which required a considerable amount of core drilling especially for the foul drainage stacks and soil vent pipes.  

 As the building was of rib and core construction, co-ordination of all the additional core drilling was required. Similarly, regarding the location of plant, the hot water plant and tanks. For this, the building was vertically split into four zones – each zone having their own hot water generating plant and storage tank for a central circulating system, each zone supplied 5-6 floors to limit pipe sizes and high water pressures from the tall high rise building. Original design was to be a heat pump system, however once structural load limitations were known this was changed to gas geysers and a new Egoli gas supply.

The existing basement booster pumps were no longer installed or operational, so a new bulk storage tank and booster pump set were installed with only one of the roof water tanks being suitable for refurbishing, cleaning and re-using. Due to the nature of the building’s lightweight construction, the basement bulk water storage tank could not be placed directly on the basement level’s first floor. A dedicated structural beam supporting structure bolted to the columns and suspended above the basement floor had to be installed before the bulk water storage tank could be installed.

At the onset of the project, there was a required element of employing local community and up-skilling through Jo’burg at Work and Expanded Public Work Program (EPWP), the design kept to more traditional materials of copper pipes for water services and uPVC for waste and foul drainage. In this way it would be easier to up-skill the local community with known wet services construction materials without having to buy expensive tooling as required for installing such as Pex-Al-Pex for the water services. 

Between the ground floor shops and the first floor is a service zone of approximately half a floor. This zone contained an (now redundant) air conditioning plant which the client did not want to pay to be removed. In this service zone all the horizontal drainage was installed that collected from the foul drainage stacks above from the various residential units, before dropping at two specific points to high level Basement 1 and connecting to the exiting sewer outfall. This required on site co-ordination and sometimes re-routing of pipes to achieve the necessary falls and installation.

The whole development is built in accordance with the Social Housing Regulatory Authority (SHRA) guidelines.

 

Plumbing Africa (PA) spoke to Matthew Buirski of GDM Plumbing & Projects (GDM). The responsible person for the plumbing installation was Gareth Buirski:

(PA) Before the renovations proceeded were the old pipes and wastewater systems purged and cleaned out and tests done to ensure no diseases remained such as legionella and Pontiac fever?

(GDM) The old and dilapidated system was stripped and removed, and a new system installed.

(PA) If new ones were installed, which pipe and fittings were installed and why was this selected? To what SANS specification were these installed?

(GDM) The following system were installed 1. Copper Water Pipe system.  2.PVC Drainage.  3. Galvanised main riser. SANS 10252 – 2.

(PA) What sanitaryware and brassware were installed and to what SANS specifications?

(GDM) All items meet SABS and SANS Specifications. White vitreous china wash hand basins, WC suite, Grade 304 18/10 stainless steel single end bowl sink, acrylic Perspex baths, together with all pipes, fittings and fixtures and a 22mm ultrasonic smart water meter including adaptors to copper pipes.

(PA) Does the building have a reserve water tank?

(GDM) Yes, the building has a reserve water tank situated on the roof. 

(PA) Are there any water saving innovations introduced?

(GDM) There are no water saving innovations per se on site, but the existing gas systems within JHB CBD was utilised in the central hot water rooms to heat water. This resulted in a massive electricity saving to the end consumer.

(PA) Was a wet services engineer employed?

(GDM) Yes, Simon Olivier from Design-One Consulting Engineers (PA: See engineer’s input)

(PA) What were the plumbing challenges faced in refurbishing an office block into residential units?

(GDM) The project was relatively straight forward, following engineers design. (PA: Refer engineer’s comments). One of the obstacles in converting an old office building into a residential building was creating entirely new plumbing ducts for drainage and water. This was achieved by coring through the existing slabs in the new duct locations, whilst a simple exercise, great care was needed to make sure ducts aligned to create an aesthetically pleasing installation. Being the second contractor on site, we also faced the challenge of inspecting and testing all previous installations making sure they meet SANS standards and worked correctly, this process was undertaken in each room and duct and signed off with engineers.

List of professionals:

Client

JOSHCO

Nkululeko Magubane

PQS

Theba Consultants

Haroon Bhyat

PM and Designer

Savage + Dodd Architects

Heather Dodd

Wet services and Fire

Design One Consulting

Simon Oliver

Electrical, Lifts

Risimati

Mangalani Mavukane

Structural

Calliper

Mukudzei Gumbo

Main Contractor

Raubex Commercial

Nick Christoforou

Juan Voster

Juan Jardim

Jacobus de Klerk

Sub-contractors

Wet works contractor

GDM Plumbing – Matt & Gareth Buirski

HVAC and Extraction contractor

Shamus Rennie.

Ryan Rennie

Lifts contractor

V3F – Nico Raphadu

Internal Finishes

PC Builders – Chris Jiyane

Internal Wall system

Everest Pakhamani

Matthews Pakhamani

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