Traditional cast iron guttering was chosen for its durability as well as beauty, and when maintained can last 100+ years, but this does not make it hard to work with. As with any other situation, prevention is better than cure, and establishing a regular maintenance routine will provide the most effective way of ensuring longevity.
Cast Iron Rainwater Systems
With care and attention, there is no reason cast iron rainwater systems can’t last just as long as they previously have. We aim to provide a description of the material, a best practice maintenance, and care plan, and signs to look for which may indicate deterioration.
If you are uncertain about anything concerning your cast ironwork, we advise contacting Tuscan Foundry first, and we will be happy to discuss and provide a potential plan of action for ironwork that needs specialised care.
History of Cast Iron
Cast iron has been used for centuries and was used in architecture in the pre-modern period, the 13th century Indian “Konark Sun Temple” using iron beams to support its structure.
Cast iron was first used in pagoda construction in Tang Dynasty China. Texts by the Japanese Buddhist monk Ennin describe in detail the cast-iron pagodas and statues widespread in China during the 9th century.
Latter and more commonly it has been used and found in 18th and 19th-century architectural ornamentation rainwater goods. Cast iron has a higher carbon content than wrought iron and is formed by pouring its molten form into a mold, usually made of two halves, enabling it the possibility of creating larger sections than those produced in wrought iron by a blacksmith.
The use of a mould also enables the foundry to produce items multiple times and of a particular casting.
A Brief History of Rainwater Systems
The first documented gutter installation dates back to 1241 when the Tower of London had a gutter fitted to protect its new whitewashed walls, but throughout history, rainwater systems have been made of many materials, including lead, zinc, and copper, to today’s modern equivalents of aluminium, steel, and PVC.
Until the late 18th century, the installation of rainwater systems, gutters, and pipes was reserved for high-status residences and ecclesiastical buildings. But with the coming of the industrial revolution and the advancements in the production of economical iron casting, other alternative materials fell out of use and the widespread adoption of cast iron rainwater systems took place across the UK.
The versatility of cast iron enabled the development of ornate patterns and designs. Embellishments and decorative cresting, ornate, ornamental hopper heads, and barley twist cast iron pipes. Depending on the status of the property, a smaller property would have used a simpler plain round rainwater system.
Care and Maintenance of Cast Iron Gutters
The longevity of cast iron rainwater systems can be vastly increased with care and attention, where prevention is better than cure. Establishing a regular maintenance routine will provide the most effective way of ensuring the longevity of your gutters and pipes.
Inspections in both autumn and spring, where cast iron gutters and hoppers should be cleaned out regularly to remove vegetation leaves and debris and, clearing of the downpipes at the base where excess water can encourage plant growth, and further deteriorate the ability of rainwater to escape.
Leaf guards can be fitted to gutters and wire balloons placed at the top of downpipes to help reduce blockages occurring. Though these should also be checked regularly for blockages. Fittings are best checked during heavy rain, where issues become more apparent.
Preparation and Painting of Cast Iron Rainwater Systems
Cast iron guttering and downpipes should be painted periodically when it becomes apparent that the surface finish is deteriorating, this will be dependent on the location, with rainwater systems in coastal areas requiring more frequent attention. Particular care should be taken to paint difficult access areas (e.g. the back of downpipes and cast iron hopper heads) as these are particularly susceptible to corrosion.
Small areas of corrosion can be removed using a chisel or wire brush and sandpaper before repainting, taking care not to damage the ironwork, and avoiding using mechanical tools.
More Significant Restoration and Repair of Cast Iron Guttering
Each property project should be decided on an individual case basis, whereby the historical significance, budget, and performance requirements will be taken into consideration.
Where it is necessary to undertake, bare metal restoration on serious corrosion this should only be undertaken with professional consultation.
Cast iron is a strong and durable material, however, failure of its protective skin (the paint layer) will significantly reduce it’s lifespan!
Minor Repairs to Cast Iron Gutters
It is generally safe for minor repairs and refinishing to be undertaken by the property owner, whilst following some basic procedures.
- Ensure all surfaces to be finished are clean and free from dirt, grease, and corrosion
- Any small holes should be filled before painting to prevent water from seeping in and getting trapped.
- Ensure the paint you intend to use is compatible with the existing paintwork. If uncertain seek advice before undertaking from Tuscan Foundry (see Coastal Paint Finishes where applicable)
- Existing sound paint should be keyed/roughened with sandpaper to help paint adhesion
- Weather & timing – Cold weather can hinder the paint curing process and a breeze can result in debris sticking to your newly painted surface. The warmer months of the year are best.
Other Factors Which May Lead to the Failure of Cast Iron Gutters and Pipes
- Vegetation growth can cause blockages in gullies, drains, and downpipes.
- Mechanical Damage, gutters are particularly susceptible to edge damage if objects are placed against them.
- Misaligned gutter components, become ineffective
- Poor repairs can cause ongoing problems
- Fitting of the wrong size components can often lead to leaks and overflows.
- Fractures cause water that freezes within pipes
- Infrequent or badly undertaken paintwork, particularly to the backs of downpipes and hoppers.
- Badly sealed and/or leaky joints are prone to further corrosion, freezing, and deterioration.
Signs of Rainwater Systems in Need of Intervention
Both external and internal warning signs on a building can indicate potential problems:
- Excess algae or plant growth
- Erosion to mortar joints and masonry work
- Staining of walls behind rainwater goods
- Render, brickwork or masonry saturated with water leading to failure
- Rot to any external joinery
- Excessive water build up in drains
- Mouldy and damp walls and ceilings
- Decay and rot of wooden skirting boards and/or timber wall panels
- Dry rot occurring in hidden structural timbers
Repair and Replacement of Cast Iron Guttering
Cast iron can be particularly difficult, though not impossible, to repair and we would advise seeking help and advice from an expert or iron foundry, before proceeding.
The majority of repair works should be carried out by qualified and experienced professionals using traditional materials and techniques. It is always preferred to retain as much as possible of the original fabric and only to replace components that are completely beyond repair.
Due to the thickness of the material used in cast iron gutters welding is not recommended, as the thermal shock from sudden heat will often cause fractures. Some welding repairs may be manageable in controlled conditions in a workshop setting.
In certain circumstances it is possible to make plate repairs on the inside of the gutter, using an embedded epoxy filler, although repairs can still be visible!
Careful consideration when downpipes are being replaced, as they should be fixed away from the wall, to both facilitate painting in the future and to allow condensation to evaporate.
Galvanic Corrosion Caused by Stainless Steel Gutter Brackets and Fixings
The replacement of fixings and bracketry also needs careful consideration to avoid potential galvanic corrosion and existing fixings and gutter brackets should be re-used where ever possible. You should not use stainless steel for joining or supporting cast iron gutters unless they are isolated from the iron.
Both standard and bespoke gutter and pipe brackets are available for cast iron rainwater systems from Tuscan Foundry, these are heavy-duty steel brackets with a zinc passivation finish, alternatively, we are able to provide them in paint finishes.
Bespoke Cast Iron Gutter Replacements
Where restoration is not possible, replacement sections of rainwater goods should always be on a like-for-like basis. Tuscan Foundry can provide advice and solutions to typical problems and can create bespoke cast iron gutter patterns to match the existing cast iron rainwater system (see Chiltern Firehouse example). Replacement sections ought to match the original both in dimension and appearance.