Many of the UK’s libraries not only provide a place for local residents to access books, computers and other services, they also provide a focal point for the community. That’s certainly the case at New Eltham library in South London, a 1920s building that is an attractive local landmark as well as a valued community hub. Maintaining the building falls under the remit of Greenwich Council, and, by keeping the fabric of the building in good order, the council not only protects the library itself but also all the books and equipment inside it.
New Eltham Library has a central flat roofed area surrounded by pitched roofs with box guttering to protect the joints between different areas of the roof. Maintenance was required to maintain the integrity of the box guttering and protect the flat roofed area from leaks and the challenge for Greenwich Council was to carry out these essential works whilst keeping the library open for business.
Business As Usual
The solution was the specification of a solvent-free liquid waterproofing membrane system, Kemperol 2K-PUR from Kemper System. Because it’s solvent and fume-free, the system could be safely applied while the building was occupied.
Explains Harry Cowell, managing director of Kemper System: “For this type of job the client needs to be confident that there is no health & safety risk to staff or library users and that the library will retain the same pleasant atmosphere while work is taking place. In this scenario we recommend our solvent-free cold liquid applied waterproofing membrane, Kemperol 2K-PUR. Not only is it a practical option during the roof refurbishment but it offers a durable solution with a 20-year guaranteed service life.”
The only solvent-free, wet-on-wet, cold liquid-applied waterproofing system on the market, Kemperol 2K-PUR is based on a vegetable oil formulation, 80% of which comes from renewable sources. It is a two component system with a non-woven fleece incorporating 25% recycled plastic bottles saturated by the liquid resin.
Explains Archie Gemmell from roofing contractor, Capital Roofing: “The solvent-free system helps clients tick the boxes for environmental responsibility and sustainability but it also offers excellent waterproofing performance. And because it’s cold applied, there’s no need for any heating equipment on site, which helps to reduce the health & safety risk, particularly at a public building like New Eltham Library.”
The existing Asphalt roof was located above the library’s main hallway and had been coated with a solar paint finish to protect it but this was beginning to deteriorate. Capital Roofing began by cleaning the roof area, carrying out minor repairs to create a more even surface and abrading the solar-painted surface with a wire brush to create a keyed substrate.
Explains Archie: “The Kemperol 2K-PUR system bonds with almost any substrate so one of the benefits of using it was that we can simply apply it over the top of the existing flat roof surface and it will create a fully-bonded, impermeable waterproof membrane. The repairs to the asphalt were simply to create a more even surface, not to seal any leaks. Usually for a roof of this size we would prepare it by power washing the surface and mechanically abrading it but in this case, because the roof was already vulnerable to leaks, the preparation was done by hand.”
The Kemperol 2K-PUR system was used to provide a waterproof membrane for both the box guttering and the flat roof area. For the guttering, application of the charcoal grey membrane provides the traditional appearance of lead and a high integrity seal for the guttering without the costs associated with lead.
The flat roof area itself is around 200m2 and is largely a straightforward flat surface with no service units or awkward structures on the roof. And even though there is a large hexagonal roof light in the centre of the roof, the fleece component was simply cut to fit.
Archie continues: “The system is very simple to apply. The two components have to be mixed together and this is a critical element of the application process as thorough mixing of the resin and the activator allows the system to cure and form into a flexible, impermeable membrane. Once mixed, we simply apply a generous coat of the system to the roof and lay the fleece material over the top, overlapping each strip by around 5cm and pressing it down to become saturated in the liquid membrane. More resin is then immediately applied over the top of the fleece to saturate it. This completes the installation which is then left to cure for just a few hours to create a waterproofed roof that in reality will protect the building for in excess of 25years. The finished system is U/V resistant so there is no need for any kind of solar reflective top coat.”
For installation of the system around the roof light area, the Capital roofing team simply had to cut the fleece layer to shape, taking care to overlap the pieces of fleece to ensure the integrity of the system.
Eco and Effective
Despite having to work around rainy weather conditions during the installation period, Capital Roofing completed the guttering and roofing membrane at New Eltham Library within just two weeks and, thanks to the solvent-free, and virtually odourless Kemperol 2K-PUR system, the library was able to maintain normal opening hours throughout the project.