Refurbishing a listed building, commercial property, school, or church? One of the items to be included in your plans is your roofline and rainwater system.

Often this is the last part of the property refurbishment to be considered and sometimes is overlooked until the roof has been or is about to be fitted.

The four main factors to consider when specifying a roofline or rainwater system are:

 1.  What size gutter and downpipes to choose?

The first step in choosing the right size system is to perform a flow calculation. A flow calculation considers the roof size, pitch, roofing material, and the expected rainfall which will then give a flow rate.  The right size gutter and downpipe configuration is a key element to ensure quick and easy dispersion of water from the property.  Most gutter suppliers can perform this flow calculation for you and advise on the best size of gutter and downpipes required.

2.  What materials should I choose for my rainwater systems?

Your material choice is either plastic or metal and there are pros and cons for each material type.

Plastic is lightweight, easy to fit and there are a number of styles and shapes so you are sure to find a suitable one for your project.  However, plastic is prone to UV degradation, leading to colour fading and age hardening of seals causing it to fail much sooner than metal rainwater systems.

Cast Iron is the traditional option, especially if you have a listed/heritage style property and you must match to existing, it can be heavy and cumbersome to fit and will need to be repainted many times during its life span (up to 100  years) to protect it from the elements and rusting.

Sevenoak - Legion Box Gutter with Colonnade Flushjoint Square DownpipesAluminium is a lighter alternative to cast iron, and can be made from cast, extruded and pressed aluminium.  Aluminium is a naturally occurring material which is abundantly available and can be infinitely recycled.  It has a high strength to weight ratio, making it more durable and less likely to damage than plastic.  Easily formable – aluminium guttering, downpipes and roofline systems have a wide range of standard, traditional and contemporary styles.

Steel is another option, which again is lightweight and a choice for contemporary refurbishment projects, again it will need to be regularly maintained to protect it from the elements.

3.  What are the colour options?

Depending on your choice of material will depend on what coatings and finishes are available to you.

Plastic rainwater systems do come in a wide range of colours.

Cast Iron can be painted either on site, or prior to delivery to your site, and there are several traditional cast iron colours to choose from.

Polyester Powder coating ARPAluminium can be Polyester Powder Coated to your choice of BS/RAL colour, so can easily be matched to other architectural elements such as window and door surrounds.

Steel is available in a number of standard colours.

4.  How long is it likely to last?

The last thing you want from a newly refurbished property is issues caused by a failing rainwater system.  Longevity is key, and plastic guttering can fade and crack due to a low heat expansion/contraction, which can cause plastic to become brittle, weakening brackets and seals.  As such plastic systems are expected to last around 15 years.

Case Study - Arlington Avenue - Sentinel Beaded Half Round Gutter and Colonnade Flushjoint Rainwater PipeAluminium systems are less prone to damage from the elements and are lighter.  Often manufactured from a high quantity of recycled aluminium, once they reach the end of their useful life, can be recycled again with no loss of properties.  Aluminium doesn’t rust or corrode requires minimal maintenance and is expected to last for 50-60 years.  However, it may need repainting after around 30 years.

Cast Iron Gutters and DownpipesCast Iron is a traditional material and has been used as a guttering material for many hundreds of years, although it is heavy to install and may need to be regularly repainted to keep in optimal condition, it could last for up to 100 years.

Steel has a long-life span and will also need to be regularly repainted to keep out the possibility of rust due to exposure to the elements.

Other Key Factors

Heritage Protection

Case-Study---St Michaels All Angels Church---Britannia-Moulded-Ogee-and-Rectangular-DownpipesIf the property you are refurbishing is listed or within a conservation area, we suggest that before you undertake any work you obtain listed building consent from your local planning authority.

Each local authority is different and has different standards on Listed and Heritage properties. For some listed properties exact replacements are the only option.  However, other areas allow a more modern material choice which mimics the original system.  You must adhere to your local listed building regulations.

Maintenance and Installation

With all rainwater systems, we recommend that you inspect your system once a year for possible blockages or damage.  If you can wash the system down using warm soapy water and replace or repaint any elements in need of attention.



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