This guide will cover the importance of monitoring, what to look for and when, how to repair, and what to avoid (to prevent long-term problems).
It is very important that these are well maintained as leaks from them are a frequent source of water ingress to buildings and cause expensive and destructive outbreaks of dry rot. These items are made from cast iron, which can rust.
Downpipes can become dislodged or broken, or the out flow blocked.
Examine the pipework, gutters and rain-hops carefully for any cracks or loose joints – watch for tell-tale marks on walls after rain. These must be repaired before any repainting is done.
Any areas of rust should be wire brushed back to a clean bright metal surface and then primed with two coats of a suitable metal primer. For more information see Railings.
The insides of gutters were traditionally painted with two coats of bitumen or tar as this is extremely water proof and is still the best material for this use.
Clear away blockages from the out flow so the water can drain away.
Reconnect dislodged pipes and replace broken pipes with similar material (NOT UPVC)
Some older down pipes may have been previously painted with a black glossy bitumen finish. This can bleed through a paler coloured oil paint applied on top of it, giving dirty and unsightly brown streaks. To check if this is likely to happen, rub the black surface vigorously with a rag soaked in white spirits to see if the black paint will soften. If you do get streaks, then the black must be sealed with a bitumen sealer before applying an oil gloss paint, or a water based masonry paint can be used; this should not discolour.
Down pipes and the underside of gutters are frequently painted a stone or grey colour in a gloss finish to blend into the stone. One colour that is particularly successful is called ‘Jim’s mix’, which is a mixture of equal parts of BS 08 B25 and BS 12 B21. [NOTE: check if this is appropriate for Wirral Council Conservation]
As an alternative to black gloss finish, there are other excellent hard-wearing paints which are suitable, such as dark grey micaceous iron oxide paint which gives a discrete matt finish.
It is often possible to find the original colours used on doors, windows, ironwork or other painted areas by examination of the hidden paint layers.
Where the wall is being painted with a masonry paint, the down pipes may also be painted in the same material to help camouflage them.
However, changing colour from Black may require Seeking Listed Planning Permission.
Do not use plastic or PVC piping for down-pipes, gutters or rain-pots.