Walk down a terrace in Stroud or along a mill lane in the valleys and you will see them: heavy half-round and ogee gutters (an ogee has an S-shaped front profile) bolted along the eaves, with cast hoppers and square-section downpipes at the corners. Cast iron carried rainwater off houses, chapels and mills for generations, and plenty of it is still working. It is tough and it looks right on a stone or brick building of that age. It also rusts from the inside, it is heavy, and when a run lets go it usually takes a rotten fascia or some rafter ends with it.
This guide is about cast iron in depth: what goes wrong, what upkeep it needs, how a failing run is mended and when it is better to replace it. To compare it with the alternatives, read our gutter materials guide. For the wider service, start at guttering, soffits and fascias.
What a cast iron run is made of
A cast iron system is a kit of heavy castings joined by bolts, not a continuous channel. Each length of gutter is a casting with a lip at both ends. Two lengths meet at a joint, where a bolt through the lips clamps them together over a bed of sealant or putty. Fittings fill the corners and ends: stop ends, running outlets that drop water into a pipe, and angles for internal and external corners. At the foot of each downpipe sits a shoe or a gully that discharges to the drain, and at the top there is often a hopper, a cast box that catches the flow off a gutter or a waste pipe and passes it into the downpipe.
Profiles you will meet
Half-round is the plain semicircle. Ogee is the moulded profile with an S-curve at the front, common on Victorian and Edwardian houses. Some runs have a beaded or decorated face, and mills and chapels sometimes carry a deeper, square-cut channel. Matching the profile matters on a period front elevation, because the shadow the gutter casts along the eaves is something passers-by notice without knowing it.
How it is fixed
Brackets are either screwed or bolted to the fascia (the board running along the eaves) or fixed to the rafter feet where there is no fascia. Because the metal is heavy, the fixing is only as good as the timber behind it. A bracket is nothing without sound wood, and that is why cast iron problems so often turn out to be roofline problems.
How cast iron fails
The usual enemy is standing water. Leaves, moss and silt gather in the channel, water sits behind the blockage, and the iron rusts from the inside out, where nobody can see it. By the time a flake of rust shows on the outside, the casting may be thin in places. Paint that has been left to blister on the outer face lets the same thing happen from the other side.
The other common faults are mechanical. Joint bolts seize and shear when someone tries to undo them. Sealant between the lips dries out and the joint weeps down the wall, leaving a green or black stain on the stone below. A downpipe that has been blocked with debris can fill with water and, in frosty weather, split along a seam as the water freezes. Hoppers crack. Brackets pull away from rotten fascia boards, so a section sags and then holds water, which speeds up every other fault.
What the typical life looks like
One cleaning firm, Pureseal Services, writing in December 2025, gives cast iron a life of 40 to 70 years, sometimes 100 or more, against 10 to 20 for uPVC and 20 to 30 for aluminium. It is a single trade blog, so take it as a rough guide with low confidence. What we see on site fits the general point: a run that has been cleared, painted and kept free of standing water can go on for a very long time, and one that has been neglected can fail in a fraction of that.
Asbestos cement lookalikes
Not every grey, heavy-looking rainwater pipe is iron. Some mid twentieth century buildings have asbestos cement rainwater goods. Under HSE guidance, taking asbestos cement rainwater goods away carefully is non-licensed work, whereas substantial breakage puts the job in a different category. If you cannot tell what you have, say so at the survey and we will not cut, drill or scrub it until we know.
Upkeep that keeps a run going
Most of what cast iron needs is simple and regular. It starts with keeping the channel clear. Our guide to gutter cleaning covers frequency and method; on cast iron the extra point is to scoop by hand or with a plastic scoop, not a metal tool, so you do not gouge the protective coating. Once the debris is out, look at the bare metal. Scale and loose paint can be taken back with a wire brush, and rust treated before it is coated.
Painting inside and out
A bituminous or other suitable gutter paint inside the channel gives the metal a barrier against the water that sits there. Outside, the sequence is the ordinary one for ironwork: clean off loose material, apply a rust-inhibiting primer to bare metal, then top coats. Paint over a damp, dirty surface and it blisters within a season or two. Work is best done in dry spells when the metal is truly dry, and the back of the gutter, where it meets the wall, needs attention too, because that is the surface nobody sees until it fails.
Joints and bolts
Weeping joints are re-made rather than smeared over. The bolt is eased out, the lips are cleaned back to sound metal, fresh sealant is bedded in and a new bolt is tightened to clamp the joint. If the bolt will not come out, it may need cutting and drilling out, which is slow but better than breaking a casting that is hard to replace.
Last, we check the line. A cast iron gutter should fall gently towards its outlet; manufacturers typically recommend a fall of between about 1:600 and 1:350 depending on the system. Where the run has sagged, water ponds and the whole upkeep job starts again.
Repairing a section or replacing the run
The choice between patching and replacing is easier to see on a scaffold than from the ground. Our test is whether the metal is still sound. Tap it with the handle of a tool: a clean ring suggests good iron, a dull thud or a crumbling edge suggests the section is spent.
When repair is enough
One cracked length can be unbolted and replaced with a new or salvaged casting. A leaking joint is re-made. A short split can sometimes be filled and sealed, though a repair of that kind is a stop-gap on a gutter that is otherwise failing.
When the whole run should go
If rust has thinned most of the castings, if several lengths have cracked or if the fixings are failing along the line, repairing piece by piece costs more over time than renewing the elevation. At that point the real question is what goes back. On a listed house the answer is almost always like for like, new cast iron to the same profile. On an unlisted house, some owners choose cast aluminium or a good plastic to match the shape, which weighs less and does not rust.
What it costs
MyBuilder's 2026 price guide puts guttering at £30 to £70 per metre, and scaffold at £20 to £40 per m², as national typical ranges for the whole roofline. They are not cast iron figures, and cast iron can cost more than the plastic those ranges are built around. Our own price follows the survey and covers scaffold, removal, new lengths, fixings and making good.
Listed buildings, conservation areas and the Cotswolds
Rainwater goods on an older house are not just plumbing. Stroud District Council tells owners that a listing protects the whole building by law, whatever the grade, indoors and out. Altering gutters so as to touch the building's special interest can need listed building consent, so ask the conservation department before swapping material or profile. Like for like repair is the easy end of that conversation; a change from cast iron to plastic is the end where you need an answer first.
Stroud District has 41 conservation areas. Article 4 Directions cover five of those areas, and the council does not spell out whether rainwater goods fall under them, so phone its planning team first. The same team can advise on work inside the Cotswolds National Landscape.
Why the roofline goes with it
On a period house, gutter work often drags the fascia and eaves into the job. Our guide to conservation roofline work explains how we approach the boards and brackets in a protected setting. Where we find that rafter ends have rotted, we flag it at the survey, attach photographs taken on your roof, and agree the timber repair with you before any iron goes back.
The 10-year workmanship guarantee we give on our own work is in writing and covers workmanship, not the age of the iron.
Water, weight and where it should go
Cast iron does best when it is working properly, and that means getting the water away. A long, steep slope sends a big flow into one short run of gutter. The outlets, the hoppers and the downpipes all have to take it, and a single blocked pipe sends the load back up the system.
Overflow and leaks
A joint can stay dry in light rain and weep once the gutter runs full, so many cast iron leaks only appear in a downpour. Our guide to leaking gutters sets out the causes and tests in detail, and the pattern is the same for iron as for plastic: find where the water goes, then find why.
Weight on the timber
Because each length is heavy, it is worth thinking about what the roofline will carry once the gutter is full. A section holding water adds a great deal to the dead weight of the metal, and fixing screws that look fine on a dry day can be asked to carry that weight in a storm. Where brackets are going back into old fascia, we probe the timber first. Soft wood is cut out and replaced, or the brackets are carried to the rafter feet.
Taking it down safely
Lengths are supported from below as bolts are released, because a heavy casting dropping from height can crack or hurt someone below.
Deciding what to do with yours
For most owners the decision comes down to three questions. Is the iron still sound? Is the timber behind it sound? And does the house have protection that limits what can be changed? If the answers are yes, yes and no, then cleaning, rust treatment and paint are usually all that is needed. If the iron is sound but the timber is not, the work is a roofline repair first and a gutter job second. If the iron is thin, cracked or sagging along most of the run, replacement is the sensible option, and the next job is matching profile and finish to the building.
We start with a survey from a scaffold or access tower, so we can handle the castings. You get photographs of the run, the brackets and the timber, a written account of what is sound and what is not, and a written quote. Nothing is replaced that does not need to be, and what we remove is cleared from site at the end.
What to send us first
If you would like a view before we visit, send photographs of the gutter on its worst elevation, one of a joint, one of a bracket and one of the fascia behind. Tell us whether the house has a listing or sits in a conservation area. That is usually enough to tell you whether you are looking at paint, a repair or a replacement.