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Repairing Cast Iron Guttering

Over the years, many materials have been used for gutters, each with their own advantages, disadvantages and aesthetic qualities. The commonly found materials used for guttering on old buildings are cast iron, lead and, surprisingly, timber. Timber gutters are unusual unless one lives in northern England - the Sheffield and Hull areas still have much surviving timber guttering. Most of the major timber merchants have branches in Hull where guttering is still available as a stock item in several different sizes and patterns, preservative treated and at a surprisingly reasonable price. Local merchants can be persuaded to obtain individual orders from their Hull depots.

Whilst work to lead gutters will require a specialist lead plumber and timber gutters are relatively unusual, there are many period properties that still retain their cast iron gutters quite often the originals from over 100 years ago. This longevity is cast irons main advantage.

These days plastic gutters are the most commonly used solution on modern buildings, and they certainly fulfil the minimal requirements of cost and installation, but lack the more exacting essentials of longevity, maintenance, aesthetics and eco credentials.

How often do tradesmen and builders merchants tell homeowners that cast iron is maintenance prone and no longer available? Both are completely incorrect points. Most builders merchants stock or can readily order the common components, more unusual items and even bespoke items can be obtained from J & JW Longbottom Ltd (01484 682141), an Aladdin's Cave of guttering and downpipes.

The secret to longevity of cast iron work is to thoroughly paint each component up to gloss finish before installation, and for guttering this includes the insides, ideally with primer, undercoat and black bitumen paint this ensures that difficult-to-paint and vulnerable areas are protected from the outset.

Occasionally a joint will begin dripping. Once dry, this can usually be sealed with a smear of putty forced into the joint from the outside and then painted with gloss on the outside and bitumen paint on the inside. Larger leaks may require the joint to be undone and properly remade. Corroded or broken items will need replacing: undoing the original connecting gutter bolts is a simple affair if they shear off when turned; otherwise a mini grinder will grind the nut off effectively. (One note of caution whilst using a grinder on metalwork ensure that any sparks are directed away from glass, enamel or glazed ware, including pottery, because the sparks will fuse on contact leaving a rough and damaged surface. Likewise sweep up any iron dust).

Traditional cast iron guttering

TOP AND ABOVE: Cast iron guttering on old properties is often over a century old — a testament to its longevity. Assuming the guttering is not beyond repair, it is always worthwhile restoring as opposed to replacing, both financially and aesthetically.

Remove the bulk of the existing jointing compound by scraping, chipping or grinding. Dry fit the replacement piece to ensure a good fit and remove to enable joint preparation. These days there are various rubber gaskets and gun-applied jointing compounds available and all perfectly serviceable.

Traditionally linseed putty was used, sometimes with additions. If using putty, sparingly apply a primer coat of oil-based gloss paint (any colour will do as it won't be visible) to the joint services, place a thin sausage of putty the full width of the joint, fit the component in place and gently tighten the gutter bolts until a snug fit is obtained. The excess putty will need trimming and smoothing at both ends of the joint, and then a generous painting internally with black bitumen paint, and externally with gloss.

Sometimes guttering will leak where it discharges into a hopper head by tracking back along the underside of the gutter. Fitting a gutter bolt through the guttering at its lowest point directly over the hopper head to form a drip easily cures this.

Another potential problem can arise from the traditional practice of using one gutter bracket per length of gutter, leaving one end dependant on its neighbour this is fine whilst everything remains sound, but makes repairs awkward and any breakages from snow, old age etc can lead to a domino effect, bringing down adjacent components. Prevent this scenario by fitting extra gutter brackets.

Although it sounds obvious, after installation or repair work, gutters should be tested. A bucket of water poured into the far end will find any leaks and also indicate if any adjustments need making. Old buildings can settle considerably and sometimes the outlets need to be reversed.

And finally, for maintenance, cast iron guttering, like all gutters, needs cleaning out every year or two to prevent the build up of debris. This, together with the application of black bitumen paint to protect the inside every five or six years, will generally be sufficient to ensure many trouble-free years of use.

Cast iron look-a-like

ABOVE: If you do need to replace, genuine cast iron looks fantastic, but is expensive. Consider a looka- like product, such as this from Brett Martin. brettmartin.com.

5 Comments

i have the old cast iron guttering and have lost 3/4 lengths of it that the snow has brought down and was wondering how much it would cost to have it replace and fitted, my neibour has lost the same and would want hers doing as she is an elderly lady and i said i would ask around on how much it will cost
See this was posted in 2007 but still good. I was wondering what to do with my cast iron gutters. They are still good but need repainting and I am getting huge estimates from painters to repaint, as our ladders don't reach. Thanks for your advice I'll paint the inside with black bitumin. Can I pass on a tip? You may not approve, but the bendy bit of the gutter was holed and I just taped it up with aluminum tape and then painted that along with the rest of the gutter. Visually, only I know where the repair is. That was over 10 years ago, the repair is still good and unvisable, the paint is peeling off the sound gutter part not the painted aluminum tape repair!
...but not sure if they can arrange for a one off slightly off right angle piece of cast iron guttering. Try www.greenrainwaterstore.co.uk and see if they can arrange for the special piece. I know they deal with a foundry in Yorkshire so you may be in luck.
I am preparing to instruct builders to repair and paint the ogee section cast iron guttering and downpipes pipes on our Victorian terraced house. We have a particular problem. It is a corner house but the corner is a little MORE than a right angle. Previous builders have botched the job, by using a right angled corner section. Of course the joints with the adjoining straight sections don't fit and tend to leak as a result. Is thee anyone who - for a not to high price - can make a one-off corner section to suit this situation ?
We are looking to renovate our cast iron gutters rather than replace and have found a company called H D Sharman who produce a rubber insert to go inside the existing gutters to convey the water away, I wonder if this maybe of some use to you.