Why Important
If pipework becomes blocked, water cannot flow away and will back up, and run down the face of the building washing out pointing or eroding stonework, or may find its way into the building.
What to look for
The rear elevations in the Georgian Quarter generally have plain half-round, double beaded cast iron gutters and downpipes.
Victorian buildings often have decorative ‘ogee rhones’ (S-Shaped Gutters), hoppers and downpipes and most patterns can still be cast today.
Other signs of problems are damp staining on walls, green algal growth on stone or failed render.
Cast iron rusts if it is not protected with paint. Check for signs of rust, especially at the backs of rhones and downpipes which are hard to get at.
When to look
Downpipes need to be checked regularly and cleared of leaves, debris and vegetation to operate properly. Ensure they are not blocked by debris at the base outflow.
How to fix
New cast iron should be painted with one additional coat of primer, two coats of undercoat and two coats of top coat prior to being installed.
When repainting, ensure all the rust is removed by wire brush and sandpaper first, and then repaint using a proprietary paint system specially designed for metal. Painting is usually black, however variations may be allowed such as dark grey or stone to match the colour of the building behind, however you are recommended to Seeking Listed Planning Permission before repainting.
Avoiding creating problems
UPVC pipes are not appropriate, regardless of colour.
A proprietary mesh leaf guard should be fitted at the top of downpipes to stop leaves blocking them further down, or if the water is gathered in a catch pit (a sunken lead box before going into the down pipe) a mesh box is placed into the catch pit.
Historical background
Early downpipes would have been made in lead but by the 1800’s cast iron rainwater goods were being mass-produced locally. Cast iron is made by pouring molten iron into sand casts and it is still the process used today. As the industry took off, more elaborate mouldings became available.