There’s only one cast iron rainwater

Posted by: julie    |   Date posted: 02/10/2017

Speaking as a market leading cast iron rainwater supplier, I suppose cast iron should be flattered that look-a-like products have been developed and positioned as the genuine article. And we’re not surprised. After all, cast iron is the look that many people love so why not try and imitate it? But that’s all it is, a look, and people should be careful not to assume ‘cast iron’ effect plastic also has the performance attributes of the real thing or its suitability for cast iron applications.

Cast iron effect plastic has its cost advantages, but there are risks to installing it where only the strength, robustness and long-lasting looks of premium cast iron will do. The two materials are suited to very different markets, with very little overlap.

Designed for tomorrow’s climate?

Our climate is changing faster than expected and, from a product and materials perspective, that means designing and building for tomorrow’s weather, not yesterday’s. Designers have to consider how different materials behave in the warmer, wetter, windier weather that’s on its way, and the amount of UV light products and materials will be exposed to.

It often takes a shock to get us to change how we build. We got a foretaste of this in a hot spell over the summer when some builders were surprised by coloured plastic guttering expanding and distorting so much in the heat that it had to be replaced before the scaffolding was removed. Coloured plastic and dark colours especially, absorb heat and expand greatly.

A product like rainwater has a lot to do. Its job is to reliably protect the building from the extremes of weather while looking great (and enhancing the look of the building) with a minimum of upkeep, trouble and cost over many decades in a changing climate. That’s a tall order given the variety of building types, sizes and ages it will be installed on, and the functions of the property and extremes of weather it protects against.

Specifiers, contractors, builders and property owners rely on specifications and robust product application advice to establish clearly the limits and suitability of the product. Sometimes people see what they want to see, and let wishful thinking push the boundaries of what is sensible. But post-Grenfell, the question of what products should be used where – not just for fire safety – have taken on a greater significance. No doubt, technical teams in all product categories across Britain are looking with great care to make sure their specifications and advice are correct.

Different materials for different markets

It’s perhaps easy to think that cast iron rainwater and cast iron effect plastic rainwater are interchangeable, and that either could be substituted for the other, in any project. But that’s not true. The materials they’re made from are inherently suited to very different markets.

Plastic rainwater is lightweight and easy to install. It’s ideal for mass-market housing. Most comes with a limited range of standard through-colours. The ‘cast-iron’ effect is applied as a thin paint coating to the plastic, and being plastic it expands in the heat and creates significant movement. Coloured guttering expands considerably more than white, causing the creaks and groans on warm nights as it expands and contracts against the seals and joints to keep homeowners awake. Some products minimise this noise, but significant expansion and contraction is an inherent property of the material. It’s this movement against the seals and joints that creates gaps where leaks occur. Heat can also cause the gutters to twist and warp. With age, plastic tends to fade and discolour. With age also, UV light causes embrittlement in plastic and coatings so they become vulnerable to cracking and chipping.

Cast iron is perfect for period and conservation buildings, heritage public, listed buildings and self-build homes. It is a premium solution to protect premium properties. It would not be cost effective on new mass-market housing where, if looked after properly it would probably outlast the building itself.

Cast iron is incredibly tough, long lasting and 100% recyclable. If painted under Apex certified factory conditions, installed and maintained properly, cast iron can be expected to last over 100 years. Perfectly protected against the weather, gutters and downpipes should not need attention for up to 10 years, with regular maintenance thereafter.