The most widely utilised waterproofing system for flat roofs is torch-on waterproofing, a method recognised for its durability and distinctive appearance. This material is typically supplied in sheets that are one metre wide, with clearly defined overlaps that make it easy to identify. When rolled up, torch-on waterproofing resembles a thick, black rubber sheeting, but it is actually made from modified bitumen, a highly effective waterproofing agent. The material is 4mm thick, which classifies it as a heavy-duty product, capable of withstanding significant wear and tear.
Upon installation, the product is usually finished with a coating of aluminium paint, which gives it the characteristic silver-grey colour seen on many flat-roofed buildings. This final layer not only enhances the roof’s aesthetic appeal but also adds an extra layer of protection against the elements. The lifespan of torch-on waterproofing can vary significantly depending on the quality of the product. Cheaper imports typically have a life expectancy of around 10 years, while premium products can last up to 40 years. Most installers provide a 10-year guarantee, but for optimal performance and longevity, manufacturers and professional roofing contractors recommend that the system be inspected, repaired, and re-coated every three years.
However, it is not uncommon for the waterproofing guarantee to expire or, in some cases, for the installer to no longer be in business. Additionally, regular maintenance is often neglected, which can lead to significant issues. Failure to properly maintain the waterproofing system can not only result in leaks and subsequent damage to the building structure but also drastically reduce the lifespan of the waterproofing itself.
Common issues encountered with torch-on flat roofs include:
- Loose overlaps or seams
- Loose turn-ups against walls
- Loose waterproofing at the edges of parapet walls
- Holes or damage to the waterproofing layer
- Improperly sealed outlet pipe openings
- Waterproofing failure in corners
- Defective waterproofing around roof protrusions
- Deterioration of the protective aluminium paint coating, which can accelerate the degradation of the waterproofing system
Professional roofing companies employ crews trained to identify and address all of these potential problem areas. After repairs are completed, the roof is thoroughly cleaned and a new layer of reflective, protective bituminous aluminium paint is applied. This maintenance process not only restores the roof’s protective capabilities but also extends the overall lifespan of the waterproofing system, ensuring the long-term integrity of the building.
Crack to waterproofing at outlet pipe opening.
Waterproofing turn up pulling loose
Crack in parapet wall above waterproofing tun up.
Aluminium paint coating has weathered and requires over coating.
