The general assumption is that as a waterproofing system is designed to prevent water ingress, standing water will not be an issue. However, the reality can be different as the long-term interaction with water ensures that ‘hydrolysis’ becomes a factor. The simplest definition is that hydrolysis is the decomposition of substances by water into their primary products. If the substance in question is a waterproofing system or membrane, this poses an issue for the long-term integrity of the waterproofing of the structure.
In roofing applications, there are numerous reasons to avoid standing water, ranging from loading to slip hazards, and for inverted applications in particular, the thermal performance of the construction may be affected. Clearly, given the reality of refurbishment, standing water and ponding water cannot always be avoided and in these applications, specifiers and users need to ensure that the selected waterproofing system is fully capable of dealing with any potentially long-term standing water and is resistant to the effects of hydrolysis.
Zero pitch roofs
Notwithstanding the requirements of British Standards, over recent years the terms ‘zero pitch’ and ‘completely flat’ have been used in the roof waterproofing industry. By its nature, designing a roof to be to zero pitch or completely flat creates an increased risk of standing water, and even with roofs designed to a fall of 1:80 or greater, the likelihood can often be that the ‘as built’ roof construction or parts of the roof may hold water. If this is the case, the designer needs to ensure that the waterproofing system is suitable and that any guarantee will not be invalidated due to a lack of falls, or the presence of standing water.
The demands of new build applications may be similar, although the structures to be waterproofed may be less robust with higher potential for movement. In all of these applications, where a roof is subject to standing water, or the waterproofing is permanently submerged – Triflex systems meet all the required criteria, and with their exceptional hydrolysis resistance, are designed to deal with everything from a completely flat roof to a pond
In many existing non-roofing applications such as fountains, cascades, water features and ponds, the original construction will not have featured specific waterproofing or liners. In some instances they may have been treated with a coating designed simply for ingress control. The result can be significant long-term water loss and a lack of protection to the underlying substrate.
Should the need arise to retrospectively fully waterproof these structures, the waterproofing solution needs a number of specific properties to deal with the extreme conditions, including:
The ability to deal with moisture within the existing, often porous substrate
- High levels of adhesion to the substrate
- The ability to seamlessly waterproof complex shapes and details from pipework, fountain nozzles, electrical cables to sculptures or rocks
- Non-toxic and fully resistant to water treatment chemicals
- High levels of impact and puncture resistance should the water feature be trafficked
- Dynamic crack bridging and suitability for extremes of temperature (many water features freeze in the winter)
- Hydrolysis resistance