Original cast iron guttering on a period home is worth saving where it can be saved. It outlasts almost everything fitted since, and a repaired original system is nearly always preferred by conservation officers. But not every run is repairable, and patching a system that has reached the end is money spent twice.
Five things we look at on survey
1. Rust depth. Surface rust under flaking paint is cosmetic and normal. Rust that has laminated the metal into flakes you can lift with a screwdriver, or that has perforated the base of the gutter, is structural.
2. Cracks. A hairline crack in a sound section can be repaired. Cracks radiating from bolt holes, or a section cracked along its length from frost damage, mean that section goes.
3. The joints. Cast iron gutters are bolted with a putty or mastic bed. Failed joints are the single most common cause of leaks and are entirely repairable — the gutter is fine, the seal is not.
4. Brackets and fixings. Corroded rise-and-fall brackets, or brackets pulling out of rotten fascia timber, will let the run sag and hold water. Replacing brackets is straightforward; the rotten timber behind them is the real job.
5. Falls and standing water. Water sitting in the gutter after rain tells you the run has dropped. That is a re-hang, not a replacement.
When repair is the right answer
If most sections are sound, the profile is intact, and the failures are joints, brackets or paint, repair wins. The work is:
- carefully taking down the run and labelling sections
- shot-blasting or hand-stripping back to bare metal
- priming with a proper metal primer and finishing with two coats
- re-bedding joints and re-hanging to a corrected fall
- replacing only the individual failed sections in matching profile
Done well this buys another forty to sixty years, and keeps the original fabric.
When replacement is honest
Replacement makes sense when perforation is widespread, when previous repairs have already patched a large proportion of the run, when the profile is a lost pattern with too many failed sections to match, or when the roof is coming off anyway and access will never be cheaper.
At that point the choice is new cast iron — right for listed and prominent elevations — or cast iron effect powder-coated aluminium, which is lighter, needs no repainting, and is widely accepted on unlisted period homes and on secondary elevations. We explain both, with the case for each on your particular building.
The cost of getting the sequence wrong
The most expensive version of this job is repainting a run that then fails, because the scaffold or access cost is paid twice. Access is a large share of the price on a tall period house, so the decision to repair or replace should be made before the scaffold is booked, not after.
We survey cast iron systems on period homes throughout the Cotswolds, Oxfordshire, Gloucestershire, Wiltshire and Berkshire, using access equipment and drone survey where elevations are hard to reach. Arrange a survey and we will give you a straight recommendation, including when the answer is to leave it alone for another few years.