The weather beaters
Despite the emergence of ‘look alike’ products aimed at the heritage market, cast iron rainwater systems still take a lot of beating for both looks and performance and remain the first choice for traditional or listed properties.
The demands from modern rainwater systems are highly stringent and extremely varied. Not only must the product perform well and be long-lasting and durable, but it must be cost-effective, easy to install, require minimal maintenance, and offer optimum sustainability – and, on older properties, deliver an appearance faithful to the vision of the original architect.
The Government’s Planning Policy Guidance, PPG15, requires ‘like for like’ replacement of existing cast iron pipes on buildings of historical importance, while on prestige projects, the use of inferior materials just will not do.
While cast iron products have traditionally been seen as a more expensive option, the picture looks very different when whole life costs are considered; there is a significant difference between cast iron and plastic systems in the longevity of the materials. Cast iron has a typical lifespan in excess of 50 years (and it is not uncommon for it to last 100 years) whereas plastic pipes and gutters usually only come with a 10–20 year life expectancy, meaning three or four replacements during the cast iron system’s lifespan. And the argument that cast iron systems involve a lengthy on-site finishing process involving the application of undercoat and topcoats (which adds time and cost to the installation process) certainly does not apply to the latest pre-painted cast iron systems.
Another myth is that of maintenance. Some plastic look-a-like systems are quoted as maintenance-free with a 10-year guarantee. Ten years fades into insignificance against the lifetime expectations of cast iron – indeed, when cast iron systems do need replacing, it is usually after a lifetime of service, not a mid-term failure. Today’s customers, specifying and installing new cast iron systems, also have the benefit of the considerable product development that has taken place over the generations that the original systems have been in place; this ensures you need have few doubts about future longevity of a proven material .
Meanwhile, the need for periodic re-painting only applies to cast iron systems supplied primer coated for on-site painting, while the coatings on cast iron systems supplied with an epoxy powder polymer should give an expected coating life in excess of 20 years – twice that of the ‘look alike’ systems.
Today’s cast iron gutter systems are simple to install using a low modulus mastic sealant, or gutter jointing kits for the half round profile that uses rubber gaskets. In addition, they carry all of the traditional benefits of strength, durability and rigidity. Homeowners need have no worries about severe weather conditions. Cast iron is secure against the weight of snow and will withstand high winds without any squeaking or rattling while, at the other end of the scale, gutter systems will not twist or creak when temperatures rise.
The inherent strength of cast iron also makes it highly resistant to accidental damage and to vandalism. Indeed, modern production methods, involving centrifugal spinning of the pipe rather than traditional sand casting, are delivering pipes that are stronger than ever, with none of the ‘thin’ spots which have previously weakened these products. 
Finally, there is the issue of the environmental impact. Cast iron is produced from 97% recycled material (scrap) and, in turn, is 100% recyclable and has a residual value at the end of its life. While plastic systems claim a level of recyclability, this is often complicated and more costly to achieve than it is worth - and it is widely recognised that discarded plastic systems will end up in landfill. And if the homeowner wants to save rainwater to use on the garden, rainwater diverter kits can be fitted to the downpipes to connect to standard water butts.
Given that aesthetically cast iron is well ahead of its counterparts, it is no surprise that cast iron remains the preferred option for homeowners wishing to combine cost-effectiveness and performance with traditional aesthetics, something that alternative materials simply cannot match.
Mike Rawlings is Marketing Manager for rainwater goods with Saint-Gobain PAM UK, who are specialists in iron technology.
