This building is owned by BBC Pension Trust and is a major Sainsbury store in Plymouth’s main shopping centre. CBRE determined that the roof was failing badly so we were contracted to cut and seal the existing roof membrane and then install a new torch on bituminous felt system on top, a project valued at £251,251.
The client required the store to remain open 18 hours during the week and eight hours on Sunday during the re-roofing operation over Christmas.
This meant deliveries and works had to be planned meticulously in co-ordination with the store. Scaffolding, for instance, was installed before 6am while materials were off-loaded within 20 minutes on a just-in-time basis as was the 150 tonnes of stripped out roof material.
Plant on the roof was also being renovated so all works around this were planned in collaboration with the M&E; contractors, again to minimise disruption.
The works comprise cutting and sealing the existing roof membrane and providing and install a new torch on bituminous felt system on top of the existing as described in the Specification (drawings and performance specification). As part of these works the main contractor will need to employ the named Mechanical and Electrical sub- contractor to decommission any plant (such as condensors, vents, etc) located to the roof, so that these items can be lifted and the roof membrane dressed underneath them, as described in the Specification (document: ‘Roof Plant Scope’). Following this, the Mechanical and Electrical sub-contractor will need to re-commission the plant. Other ancillary works include replacing missing parapet capping panels, repairs to cable ducting and installation of new earthing systems, following the removal of existing. . 150 tonnes of rubbish.
The roof measured more than 5000m² and was covered with chippings on an existing felt roof.
The access and egress points was in the main car park which involved detailed planning to get materials up and the 150 tonnes of chippings off the roof and off site whilst the public were around. This ruled out weekend working and deliveries because this is the shopping centre’s busiest time, especially at Christmas.
The only space available for the site compound and the scaffolding was an area of six car parking spaces in the main park for the Armada Centre, Plymouth’s largestshopping centre. To compound the difficulties of delivering and removing materials, he car park is open 23 hours a day and has 400 car parking spaces, 100 at each of its four levels. So, the 16 tonne lorry carrying 12 tonnes of chippings had to do so early one weekday mornings while the 150 tonnes of waste stripped from the roof had leave in the same manner.
The roof was large – more than 5000m² – and had a live store underneath. Once the chipping removal was underway there is always a chance of damaging the old felt and so causing leaks.
To mitigate against this we kept specific materials on site so that we could cover any damaged areas immediately. This approach was 100% successful as we completedthe whole job with not one leak even though our operatives were digging stone chippings out of the existing membrane.
Hot works were specified and again the management of the works were worked out to keep any risks to the minimum. The main areas of risk are intake and extract fans, which might suck the flames from the torch into the building and make contact with flammable material. So our operatives were careful to avoid these areas when using torches.
In terms of overall quality our own regime of inspection was also reinforced by regular checks from the surveyor, CBRE, and from our supplier, BMI Icopal. Its technical specification manager inspected the workmanship of our operatives weekly to ensure that it met the specification upon which the company’s warranty was based.
Part of the project involved M & E subcontractors removing and disposing of two 10 tonne air handling units so we co-ordinated our activities to ensure that thiswent ahead without affecting our programme.
Throughout the project we liaised with store staff and management to ensure that the public, employees and goods could move freely without interference to the store’s business.
This project ran from September to December, so we had to take account of weather delays. These are always an important factor in the city because of it is on the coast but this winter was especially difficult, with storms such as the ‘Beast from the East’ disrupting work.
The nature of the job meant that we could not work at weekends to deal with any shortfall in progress because the store, the shopping centre and the car park was very crowded at this time.
But our team of six to 10 operatives were able to keep to the program through careful scheduling.
Health, Safety and Environmental Management:
The site was well-designed in terms of safety, so the main areas of risk were intake and extract fans. There was a possibility that a backdraught could suck the flames from the torch into the building and make contact with flammable material. So our operatives were careful to avoid these areas when using torches.
Around 90% of the work was on one level so movement across the roof was simple and there were few handrails. There were also staircases to the other roofs and we only needed a small scaffold tower in one small area. There were no other trades to deal with either, apart from the M&E; subcontractors. They removed the air handling units but this was done in two days.
Training, Assessment and New Technologies:
Training is a matter of pride for this company. We started 16 years ago with just three of us and now there are 44 staff, all of whom have come through our training schemes.
We recruit a minimum of two apprentices each year and they learn all aspects of the trade: slating, tiling and flat roofing. The quality of training is shown by their short-listing two years running in the BMI Redland Apprentice of the Year competition.
A large project such as this, in a difficult location and a challenging time of year, is ideal for training apprentices the importance of meticulous planning and communication with the client to delivering a successful project.
CBRE complimented us on the job. They were very pleased that it went without any issues and went according to programme.