Cast Iron Downpipes

Cast iron downpipes come in different sizes and profiles, and choosing the correct ones is not always an easy task, especially if you are replacing an old rainwater system where the original fittings have been there for decades.

We at Cast Iron Warehouse provide genuine Alumasc Apex Heritage cast iron rainwater pipes. The range of fittings includes round and rectangular profiles, which are manufactured using traditional sand casting techniques and produced to BS460 standards.

Round or Rectangular Cast Iron Downpipes?

The more common choice are round cast iron downpipes which are typically found on Victorian terraces, period cottages and other traditional houses. Our range of round cast iron downpipes include 65mm (2.5"), 75mm (3") and 100mm (4") sizes.

Rectangular profiles provide a different look, and their flatter form suits very well with traditional Moulded Ogee guttering and more decorative architecture.

If you are replacing a traditional 4" x 3" rainwater pipe, then consider our range of rectangular cast iron downpipes including Alumasc Apex 100 x 75mm system.

What Size Cast Iron Downpipe Do I Need?

If you are replacing your old system, then the best starting point is probably the size of the existing pipe.

There is one thing to check though. Cast iron pipe sizes are sometimes nominal, but not the actual outside diameter. For example, Alumasc 65mm round system is actually 63mm.

Measuring both the straight pipe and the socket is recommended, especially when connecting new pipework to existing castings.

For a new installation, the size of the cast iron downpipe depends on the drainage requirements of the roof, gutter outlets and the amount of rainwater flow. Do not simply choose a bigger pipe just because of the look. We produced a helpful guide on how to choose the right downpipe size.

With Ears or Without Ears?

Some of our cast iron downpipes are supplied with fixing ears while others have plain sockets. Eared pipes have traditional cast lugs on the socket and allow securing the pipe to the building with suitable fixings. Uneared pipes require additional holders and give a more elegant look around the socket.

None of the two options is better. If you are replacing your existing system, make sure that you know how the original system is fixed.

What Fittings Will I Need?

A complete cast iron rainwater system will probably require more than just straight downpipes. Depending on your building, you may need swan necks to fit projecting eaves, bends to change direction, access pipes for maintenance purposes and shoes to discharge the rainwater into a suitable drain.

Our Alumasc Apex range includes matching sockets, branches, brackets and offsets in various sizes and projections.

If the rainwater is being discharged from a roof valley or parapet outlet, then you will probably need a hopper head. Check our range of cast iron hoppers which are available in round and rectangular outlet versions.

Remember to ensure that the chosen fittings match the pipe profile and diameter. Cast iron components from different manufacturers may look similar, but they are not always interchangeable.

Painted Black, Primed and Custom RAL Finishes

Factory-painted black is still a popular choice for traditional cast iron rainwater systems. This finish is very suitable for older brickwork, stone elevations and heritage buildings.

Selected painted-black cast iron downpipes are available for next working day delivery if you order before 11:30am, subject to availability.

We stock primed cast iron downpipes in selected 65mm and 75mm sizes for projects which require painting of the fitting on site. Note that primed cast iron still requires suitable exterior protection.

Custom RAL finishes can be provided for projects which require specific colour. They are professionally painted, and typical delivery times are 7-10 working days, subject to confirmation when ordering. See our full paint guide here.

Replacing Existing Cast Iron Rainwater Pipes?

If you are replacing damaged pipework on your old building, we would recommend taking some photographs first. Try to photograph the pipe profile, socket, fixing brackets and offsets. Measuring the existing pipe diameter and its distance to the wall is very useful.

Sometimes only damaged shoe, loose socket or a small part of the pipe requires replacement, rather than the whole downpipe.

If you are not sure which Alumasc Apex components are suitable for your project, contact Cast Iron Warehouse. You can send us your photographs and measurements and we will help you to select the appropriate components.