Issues surrounding leakages and aged promenade tiles on the roof of Queen's Crescent Post Office, in London’s Kentish Town, had become enough of a public hazard that Polyroof were called in to provide a heavy duty, anti-slip surfacing solution.
To minimise access disruption to adjacent buildings, the client had organised a 5-day window for the waterproofing and surfacing works to be completed.
The main contractor had removed the old paving slabs and membrane back to the concrete deck underneath and carried out repairs to create a level surface.
Emperor Roofing began by priming the concrete surface to create a sealed non-porous substrate. With its quick-curing properties the Polyroof primer was ready to be over-coated only 30 minutes after its installation.
A specialist twin-pack epoxy metallic primer was applied to metal detailing sections, including ducting vents and the intricate balustrade detail alongside the communal stairwell, which also formed part of the specified works. Local reinforcements were carried out to these details involving taking Protec resin and PolyMat 450 up by 150mm before applying the full waterproofing system.
A key advantage of liquid systems is their ability to seamlessly seal around complex detailing; in this instance, the balustrades could not have been sealed effectively using a traditional waterproofing technology.
Polyroof Protec enjoys exceptional fast detailing speeds, where its formulation allows it to rapidly break down the chopped strand mat reinforcement and neatly moulds around the detail it is covering.
To the left of the stairwell, the Protec system was chased in at a height of 150mm above the level of the stairs. The termination point of the waterproofing membrane was sealed with mastic to create a fully weatherproof detail. The Protec system was dressed onto the wall abutments to the main areas but left self-terminated as new render is to be applied to the walls and taken down over the top of the Protec system.
After local reinforcements were completed, the main waterproofing system was applied to the walkway and stair areas. The two-coat Protec system was able to be rapidly installed with its 30-60minutes cure times.
Next the designated anti-slip areas were carefully masked off, leaving the exposed waterproofing to the roof perimeters, detailing and vertical sides of the step and stairs. A third coat of Protec was applied to the masked sections and, whilst the liquid was still wet, 0.7-1.2mm quartz sand aggregate was broadcast into the resin. Once dried, the aggregate was embedded within the membrane and loose sand was brushed and collected to be re-used. In order to provide an extra-tough surface that sealed that aggregate, a coating of PolyFinish was applied over the aggregate.
The whole installation was completed in four days, one day before the deadline.
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