As a great part of the soot, dust, leaves and other rubbish which falls on a roof is washed by rain into the gutters, these will gradually fill up if not cleaned periodically. Leaves are perhaps the chief offenders, especially as regards low roofs near trees. They decay and form mud.
A partly-filled gutter may do its duty well enough during normal rainfalls; but during heavy showers may be unable to carry away the water as fast as it is caught.
This is most likely to happen if the silting is worst near the lowest part of the gutter.
The overflow from a gutter may trickle down the walls and saturate them till the paper, distemper, etc., on the inside is ruined.
Creepers allowed to invade gutters are a frequent cause of trouble, as they siphon the water out of them on to the wall below. If they extend on to the roof, matters are made worse. So they should be kept well below gutter level.
Gutters are sometimes cracked b house-painters ladders. The cracks may not be visible from the ground, and be revealed only by close examination. If a wall previously dry becomes damp, scrutinize the gutter over it. In this connection it may be mentioned that down-pipes or landers connecting gutters and drains sometimes cause trouble by becoming blocked, so that in heavy rain water spurts out of the joints on to the adjoining walls.
Another cause of trouble is the sagging of a gutter towards the middle, causing it to spill. The extent of the sag can be found by stretching a string tight along the lip. The string will serve as a guide for getting the gutter back to its correct slope.
Then there are leaky joints. These must be repaired as soon as possible. A length at one end of which a leak occurs must be removed – after provision has been made for supporting adjacent lengths in position, if this is necessary. The old stopping is then scraped away and replaced by putty worked up with red lead, or a thick paste of red lead and boiled linseed oil; enough being spread over the sockets for some to squeeze out all round when the bolts are tightened. Any surplus is then scraped off. The same procedure applies to the replacement of a broken length by a new one.
As a temporary measure to protect a wall from a leaky joint, nail to the wall under it a piece of zinc, the lower part of which is bent outwards, and given a shallow V-shape. Any water caught will then fall clear.