Downpipes - Your Questions Answered

With many areas of the UK currently experiencing floods due to recent rainfall we look at the importance of effective rainfall management and answer many of the questions people ask about downpipes.

Effective drainage systems are crucial for flood control along with water collection and storage. Surface drainage systems are required to be designed and constructed to cope with rainwater that falls onto our homes and properties. Buildings typically use drainage systems, including guttering and downpipes, to deal with rainwater. Inadequate or poorly maintained rainwater management systems can result in discharge of surface water onto roads or neighbouring properties which can cause significant issues.

What is the Law on Surface Water Drainage in the UK?

The Flood and Water Management Act 2010 is the primary legislation that defines how surface water drainage is dealt with in the UK. The law states:

"Construction work which has drainage implications may not be commenced unless a drainage system for the work has been approved by the approving body."

This means any form of construction that might have an impact on surface water drainage, such as a new patio or driveway, must be compliant. The UK legislation was introduced in 2007 in response to widespread flooding.

Property owners are responsible for ensuring they have effective drainage systems in place to prevent flooding on their land along with neighbouring properties and highways. They must also ensure no contaminants are entering the water drainage system.

What is a Downpipe?

In this post we are talking about rainwater downpipes and not the form of downpipe used in vehicle exhaust systems. Rainwater downpipes are used to route rainwater, collected in gutters around rooftops, into water drainage systems. Most homes and properties in the UK use rainwater downpipes, also simply called drainpipes or downspouts, which you can typically see mounted on external walls.

Are Downpipes Compulsory?

UK legislation and building regulations require the adequate provision of what’s needed to deal with rainwater falling onto properties. These requirements are commonly met by installing guttering around sloping rooftops to collect rainwater which is then routed via downpipes into surface water sewage systems or soakaways. Alternatively, buildings can employ sloping rooftops along with a surface water collection system or a soakaway.

Many properties now collect rainwater in water butts for use in their gardens during drier periods, often when hosepipe bans are imposed.

How Do I Protect My Downpipes?

Downpipes are typically mounted on the outside of homes and buildings. Being external makes them vulnerable to both damage and use as a ladder by potential burglars or others who might want to climb onto rooftops. Downpipes mounted on walls around areas where vehicles are parked and manoeuvred are particularly susceptible to impact damage. Businesses and homeowners are increasingly keen to ensure their downpipes are protected and don’t offer any would-be burglar a means to scale a building to reach upper storey windows or the rooftop.

What’s needed is a robust, armour shield around the downpipes to protects them from being bumped by vehicles and prevent the pipework from being used as a climbing aid. Our galvanised steel downpipe covers, widely used by many local authorities, housing associations and homeowners, are the answer.

These smart drainpipe covers are attached to the wall, enclosing the downpipe in steel armour, much stronger than plastic or aluminium. The covers not only protect the valuable pipework and strengthen security by preventing use of the protected downpipe as a climbing frame, they also look great. All downpipe covers supplied by Insight Security are manufactured from Galvanised Steel Sheet to provide years of protection against the weather, and are available from stock with either a galvanised silver steel finish or overpainted with an easy-to-clean, durable Black or White powder coat paint finish. Other colours can be manufactured on request. Many people appreciate how these drainpipe covers enhance the appearance and kerb appeal of their homes and buildings.

What are Standard Downpipe Sizes?

Unfortunately, there are no ‘standard’ sizes for downpipes. Dimensions and materials can vary between manufacturers. But most modern drainage systems use either square or round guttering downpipes ranging from 65mm for a square downpipe to a diameter of 120mm for a round one. Some extra large round downpipes, typically used in industrial applications, have a diameter of 200mm. The most common dimensions are 65mm for square downpipes and 68mm diameter for round ones.

What are Downpipes Made of?

Older buildings in the UK, built prior to the mid-1930s, were fitted with cast-iron downpipes and drainage components. These days most downpipes and home drainage pipework is made from plastic. PVC-U (Poly Vinyl Chloride - unplasticised) is most commonly used but Copper, Zinc, Aluminium and Stainless steel are also sometimes used for drainage system pipework.

How Do You Measure a Cast-iron Downpipe?

The simplest way to measure a circular cast-iron downpipe is to use a flexible tape measure and wrap it around the pipe. This provides an accurate circumference measurement. To derive the diameter of the pipe divide the overall circumference by 3.14 (for pi). Alternatively, a simple calliper tool can be used to measure the overall pipe diameter.

When considering the dimensions of cast-iron pipework its important to look at the support brackets which are usually much larger and more robust than those used for modern, lightweight plastic downpipes and drainpipes.

Should Downpipes Go into the Ground?

The primary function of a downpipe or downspout is to drain rainwater into a public drainage system. Alternatively, rainwater might be sent to a rainwater soakaway that must be located at least 5 metres from a building wall and at least 2.5 metres away from a property boundary.

Importantly, downpipes should never simply discharge rainwater at the base of a wall as this can cause damage to the property and its foundations. In some installations downpipes disappear underground where they are coupled into the surface water drainage system.

What is the Life-expectancy of a Downpipe?

Cast-iron guttering and drainage system elements are incredibly robust and resistant to damage. It is claimed that well maintained cast-iron downpipes can last 100 years, or more. Aluminium rainwater drainage components have a life expectancy of around 50 years.

The generally accepted rule-of-thumb life-expectancy for Poly Vinyl Chloride (PVC-u) pipework is up to around 30 years, depending on the quality of the plastic and manufacturing. Some manufacturers claim their plastic drainpipes can last up to 100 years. But plastic pipework can degrade over time, becoming faded, brittle and more susceptible to damage.

Why do Downpipes Leak?

Downpipes can leak for a variety of reasons. Blockages can result in downpipes overflowing and if a blockage isn’t removed freezing rainwater trapped in the pipes will expand and can create splits and cracks. Older, cast-iron pipework can corrode over time and this may ultimately result in holes and cracks causing unwanted leaks.

Is it Easy to Replace a Downpipe?

Replacing existing downpipes is not a complex task, but can involve working from a ladder at height, which is dangerous. If a downpipe has been damaged, possibly by freezing or impact from a vehicle, it can be readily replaced with a new downpipe that matches the old one. If a cast-iron downpipe is to be replaced with a modern, light-weight plastic one appropriate adapters may be needed to attach to the existing drainage system.

Are Downpipe Covers Hard to Install?

Our robust, steel downpipe covers are very easy to install. Firstly, its important to make certain the dimensions of the downpipe can be encompassed by our stock downpipe covers which have a standard width and depth of 15cm. This is more than enough to comfortably enclose most modern downpipes. Downpipe covers are supplied in lengths of 2 metres with pre-drilled fixing flanges that allow the covers to be firmly flush-mounted to the wall using either masonry or security fixings (see our special fixing pack).

If downpipe covers are required to protect non-standard size or legacy cast-iron downpipes care must be taken to consider the dimensions of the pipe support brackets as these are generally too large to be enclosed by the covers. If you need non-standard size downpipe covers, call us to discuss your requirements and find out about our bespoke manufacturing service.

If you have any questions about our robust steel downpipe covers or if you have any special requirements remember we are here to help. Give us a call on 01273 092723 and we’ll provide you with free, expert advice.

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