A full system from Mapei’s Waterproofing Products for Roofing line has been specified for a repair project to the roof of an Academy School in Hertfordshire, covering a total area of 1600m².
Main contractor and installer on the project, Capital Roofing & Building Services, specified Mapei Purtop Easy making it the first major project in the UK to use the system. Prior to the application, the existing roof, which had an old PVC single ply system installed which was reaching the end of its’ useful life and had several issues which had caused leaking to the building for a number of years. Given that the school was in use, the Purtop Easy system was chosen by the contractor due to the ease of application, and how quickly it could be installed.
Prior to the application, the substrate was thoroughly cleaned by removing all dirt and loose material and once prepared, Polyglass PVC Primer was applied by roller. This rapid curing thermoplastic polyurethane primer is ideal for preparing both new and existing PVC single-ply membranes for subsequent bonding or coating. It reactivates the surface of PVC materials, allowing the surface to accept adhesives, pressure sensitive tapes, and for this project, liquid applied waterproofing.
Purtop Easy is a single component polyurethane system that can be mixed with various additives to ease application. In this case, the upstands and details were completed first using Purtop Easy, mixed with Additix P to increase its thixotropy, and to make application to vertical surfaces easier. The upstands and details were also reinforced using glass fibre reinforcement mat, Mapetex FG. The Mapetex FG was embedded in the Purtop Easy and rolled over whilst still wet.
Once the details were completed, Purtop ADY was added to the Purtop Easy for the flat areas. Purtop ADY was formulated by Mapei Research and Development laboratories and when mixed with Purtop Easy it can be applied in just one coat without forming any bubbles. The mixture containing Purtop Easy and Purtop ADY was applied to the entire existing membrane using squeegees and rollers to produce an even, consistent coat. The addition of Purtop ADY not only prevents bubbling but also decreases the curing time speeding up the waterproofing process. Purtop ADY also improves the mechanical properties of the membrane.
The full Mapei Purtop Easy system is fully impermeable, resistant to root penetration, UV rays, and fluctuating temperatures between -40°C and +80°C.