Situated in the suburb of Tokai in Cape Town, is Pollsmoor Maximum Security Prison, famous for once having Nelson Mandela as an inmate. More recently, the Department of Public Works approved a contract to waterproof the entire roofing area of the prison. Engineers, Nadeson Consulting Services, chose one of Sika’s outstanding pure polyurea membranes for the project. Contractors involved in the application of Sika’s products were Superway Construction and SPA, as sub-contractors.

Removal of the existing bitumen residue on the roofs proved extremely time-consuming, while sub-standard, aerated screeds caused major pinholes. Due to its excellent crack-bridging properties, Sikalastic-841 ST was used to prepare all roof cracks; these were initially treated with bond-breaker tape and then stripe coated with Sikalastic-841 ST, prior to the final 1.5mm thick coating.

Once the preparation was complete, the priming phase commenced using Sikalastic EP Primer II. This two part low viscosity, epoxy-polyamine resin, is designed for use with all PUR and polyurea systems and can be applied on normal to strongly absorbent surfaces. With easy application and good penetration, this multi-purpose primer provides high bond strength and short waiting times. It is suitable for internal and external use.

Sikalastic EP Primer II was then covered with a sprayed application of Sikalastic-841 ST (1.5mm thick). For waterproofing and excellent corrosion and abrasion protection on concrete, steel and many other substrates, this highly versatile, two-part pure polyurea membrane offers fast reactivity and cure time. It is applicable in a wide range of temperatures, contains 100% solids with zero VOC and is UV resistant.

Various challenges were encountered during this project; contractors were limited to working six hours per day (9am to 3pm), weekdays only; weather caused problems with rain and high moisture content delaying product applications, while strong winds affected work, especially on the upper levels where over-spraying of Sikalastic-841 ST occurred. The project also necessitated crane hire, which resulted in the need for additional hose lengths.

Upon completion, approximately 15 000m2 of roofing had been waterproofed with the highest quality products supplied by Sika. Pollsmoor Prison is guaranteed protection from the notorious Cape weather for many years to come.