Replacing old cast iron guttering sounds straightforward until you actually stand underneath it and realise you don’t know what profile it is.
Half Round? Beaded Half Round? Victorian Ogee? Moulded Ogee? And then you’ve still got the size to work out.
The most important thing is not to order from width alone. Two cast iron gutters can measure similarly across the top but have completely different shapes, depths and fittings. On older buildings it gets trickier again, because historic foundries produced a huge number of slightly different profiles over the years.
If you’re trying to match existing guttering, here’s how we’d go about it.
Quick Cast Iron Gutter Profile Cheat Sheet
| Profile | How to recognise it | Common use |
|---|---|---|
| Plain Half Round | Simple curved bowl shape with no decorative front edge | Very common on homes, outbuildings and traditional properties |
| Beaded Half Round | Same rounded shape, but with a raised bead along the front edge | Period properties where you want a slightly more decorative finish |
| Victorian Ogee | Decorative, shaped front face with a flatter back | Victorian and traditional façades |
| Moulded Ogee | Deeper, heavier-looking decorative profile, often described by width × depth | Larger period buildings and more substantial rooflines |
| Deepflow Half Round | Looks similar to Half Round but has a noticeably deeper section | Roofs needing more rainwater capacity |
Start With The Shape, Not The Size
The easiest place to start is looking at the gutter from the end. You are trying to identify the cross-sectional shape of the gutter rather than simply asking whether it looks “old” or “decorative”.
A good photo of an exposed end is far more useful than a photo taken from ground level looking up at the roofline.
If there is already a stop end fitted, photograph that too. It normally makes the profile much easier to see.
Plain Half Round Cast Iron Guttering
This is the easiest profile to recognise.
Plain Half Round cast iron guttering has a simple curved section with no decorative front detailing. Viewed from the end, it looks much like a semicircle or shallow bowl.
It has been used on all sorts of buildings, so don’t assume Half Round automatically means a modern installation. Plenty of older properties use it.
If the front edge looks smooth and the gutter has a simple rounded underside, Plain Half Round is probably the first profile to check.
Our current range includes 100mm, 115mm, 125mm and 150mm sizes.
Beaded Half Round Cast Iron Guttering
Beaded Half Round cast iron guttering is very similar to Plain Half Round, which is why the two are easy to confuse from a distance.
The giveaway is the bead.
Look closely at the exposed front edge of the gutter. A Beaded Half Round profile has an additional rounded raised detail running along the edge, giving the gutter a slightly heavier and more decorative appearance.
It isn’t a dramatic difference. On an installed roofline it can be quite subtle.
That’s why we wouldn’t recommend identifying it from a street-level photograph alone. Get closer if you safely can, or take a clear photograph of a stop end or loose section.
If you’re replacing only part of a run, matching the bead matters. A Plain Half Round fitting may be the right nominal width but it won’t give you the same profile.
Victorian Ogee Cast Iron Guttering
This one looks completely different from Half Round.
Our Victorian Ogee cast iron guttering has a more shaped, architectural front face rather than a simple curved bowl.
When viewed from the end, look for a flatter back against the fascia combined with a decorative front profile. The shape creates much stronger lines and shadows than Half Round guttering.
You’ll commonly see this sort of gutter on period terraces and more decorative traditional buildings, although the age of the property alone should never be used to identify the gutter.
There is another important clue with ogee-style systems: some fittings are handed.
You may see products described as:
- Left-hand stop end
- Right-hand stop end
- Internal angle
- External angle
That happens because the profile is not symmetrical in the same way a basic Half Round gutter is.
If the existing system has handed fittings, take photographs of them before removing anything.
Moulded Ogee Cast Iron Guttering
Moulded Ogee is usually easier to distinguish once you see it from the end.
Moulded Ogee cast iron guttering has a deeper, more pronounced section with a strongly shaped front face.
It tends to look heavier than Victorian Ogee and is often described using two dimensions rather than one, such as:
or
That is useful when trying to identify an existing system because you should measure both the approximate width and depth.
If you’ve got an old gutter that looks quite boxy from behind but has a decorative moulded front, this is one of the profiles worth comparing it against.
Again though, don’t rely on appearance alone. Older properties can have non-standard moulded profiles that look very similar without actually being interchangeable.
Deepflow Half Round Guttering
Deepflow is another profile that can catch people out.
From the front, it can initially look like normal Half Round guttering. Look at the end, however, and the difference becomes much clearer.
Deepflow Half Round cast iron guttering has a noticeably deeper section than conventional Half Round guttering.
That extra depth increases the cross-sectional area and allows the gutter to handle more water than a shallower profile of a similar width.
So if your existing gutter looks Half Round but unusually deep, don’t immediately order standard Half Round replacements.
Measure the depth as well.
We supply the Hargreaves Deepflow Cast Iron Rainwater Range.
Now Measure The Gutter Properly
Once you have a good idea of the profile, start measuring.
Try to record:
- Overall gutter width across the top
- Approximate gutter depth
- Length of the existing section
- Outlet size
- Downpipe diameter
- Any visible socket or joint arrangement
- Bracket type
- Any manufacturer's marks or cast-in lettering
The first two measurements are particularly important.
Our Cast Iron Guttering Sizes Explained guide goes into sizing in more detail, but the important point here is that profile and size are two separate things.
A 125mm Half Round gutter and a 125mm Beaded Half Round gutter are not the same product.
Likewise, a deep 100 x 75mm profile may behave very differently from a shallow 100mm gutter even though one of the measurements looks familiar.
Check The Outlet And Downpipe As Well
If you’re repairing an existing system, don’t stop once you’ve identified the gutter.
Measure the outlet and the rainwater pipe too.
You might have a 65mm, 75mm or 100mm round pipe, or an older rectangular system. The outlet fitted to the gutter needs to suit the downpipe below it.
Our cast iron downpipes range includes several round and rectangular cast iron sizes, so a quick measurement here can save you ordering the wrong outlet.
Measure the outside diameter where possible and photograph:
- The gutter outlet
- The top of the downpipe
- Bends or offsets
- Pipe sockets
- Brackets
Those details are particularly useful if you're trying to replace only one part of an existing installation.
Look For A Manufacturer Or Product Mark
Old cast iron rainwater goods sometimes have foundry names, numbers or other identifying marks cast into them.
Have a look on:
- Stop ends
- Outlets
- Gutter sockets
- Hopper heads
- Downpipe sockets
- Brackets
Don't worry if there is nothing there. Plenty of systems won't give you an obvious manufacturer name.
But if you do find one, photograph it. Even a partial casting number can make identification much easier.
Some of the better-known names you may come across on older or current cast iron rainwater goods include:
- Alumasc – the one we supply - particularly the Apex Heritage range, with Half Round, Beaded Half Round, Victorian Ogee and Moulded profiles.
- Hargreaves Foundry – a long-established UK cast iron rainwater manufacturer, best known for its Premier range.
- Saint-Gobain PAM – another major name historically associated with cast iron rainwater and drainage systems; specialist merchants still list PAM alongside Alumasc and Hargreaves.
- Heritage Foundry / Heritage Cast Iron Rainwater – supplies traditional Half Round, Beaded Half Round, Deep Half Round, Victorian Ogee and Moulded Ogee systems.
You may also find older foundry names, initials, casting codes or numbers that don’t match any current manufacturer.
Don't Assume An Old Profile Will Match A Current Stock System
This is probably the most important part of the whole guide.
Britain has had a lot of cast iron foundries over the years, and many produced their own versions of common gutter shapes.
So an old gutter may look like Half Round, Ogee or Moulded guttering without being an exact dimensional match for a current manufactured range.
That doesn't necessarily mean you're stuck.
If only a short section has failed, there may be ways to deal with the repair. For a full elevation or complete replacement, it can sometimes make more sense to replace the run with one current matched system rather than trying to connect several generations of fittings together.
Our main cast iron guttering range includes Plain Half Round, Beaded Half Round, Victorian Ogee, Moulded Ogee and Deepflow systems, so there is a good chance we can at least narrow down the closest current profile.
Replacing One Length? Be More Careful!
If you're replacing an entire gutter run, a slight difference between the old and new profile isn't necessarily a problem because the new components can all be installed together.
Replacing just one damaged length is different.
The new section may need to mate with the old gutter at both ends.
That means the following all matter:
- Profile shape
- Width
- Depth
- Socket dimensions
- Joint position
- Hole positions
- Fall
- Brackets
A new gutter being called “4.5 inch Half Round” does not guarantee it will bolt perfectly onto a 70-year-old 4.5 inch gutter made by another foundry.
This is one situation where a photograph and measurements are worth far more than guessing.
What Photos Should You Send Us?
If you're still unsure, don't send one distant photo of the house and hope for the best.
Ideally, send us:
- A straight-on photo of the end/profile of the gutter
- A photo looking along the gutter run
- A close-up of a joint
- A photo of the outlet
- A photo of the downpipe
- Width and depth measurements
- Any manufacturer markings you can find
Even better, put a tape measure in the photo. Send it to info@castironguttering.co.uk.
It gives us scale and usually makes identifying the size much easier.
If the gutter is coming down anyway, a photograph of the actual cut end or stop-end profile is probably the best image you can send.
Quick Profile Check
If you're standing underneath the gutter trying to work it out, use this as a rough starting point:
Simple rounded bowl with no decoration?
Look at Plain Half Round.
Rounded gutter with a raised decorative bead?
Compare Beaded Half Round.
Decorative asymmetric front face, flatter at the back?
Check Victorian Ogee.
Deeper, heavier decorative profile with width × depth dimensions?
Look at Moulded Ogee.
Looks Half Round but much deeper than expected?
Compare our Deepflow Half Round.
And if you're still not sure, send us the photos and measurements before ordering. With cast iron, taking five minutes to identify the system properly is considerably easier than discovering you've ordered £500 worth of fittings that almost fit!