The failure is rarely dramatic. It is a slow silting-up, a joint that drips, or a run with the wrong fall that has been quietly wetting the same brickwork for years.
Diagnosing what's wrong
Watch the run in heavy rain if you safely can. Water standing at one end means the fall is wrong or the brackets have dropped. Water spilling over the front edge across the whole run means it is blocked or undersized for the roof area.
Green staining or moss on the wall below a joint points to a persistent slow drip rather than an occasional overflow.
Repair or replace
Realigning brackets, clearing outlets and remaking joints is worthwhile on sound cast-iron or good-quality systems. On brittle, cracked plastic that has been up for decades, replacement usually costs little more than a thorough repair once scaffold or access is on site.
Seamless aluminium is rolled on site to the length of the run, so there are no joints along the straight sections to fail later. Cast-iron replacements suit period and conservation-area elevations where the profile matters.
Doing the associated work at the same time
If access equipment is going up, it is worth dealing with fascias, soffits, verge and flashing repairs and any high-level pointing in the same visit. Access is often the largest part of the cost of small high-level work.
Check where the downpipe discharges too. A gully that no longer takes water, or a pipe running straight to the ground beside a solid wall, undoes the benefit of a new gutter.
Common questions
How often should gutters be cleared?
Once a year is enough on most houses, twice where there are overhanging trees. Autumn clearance matters most.
Can gutters be repaired rather than replaced?
Yes where the material is sound. Rebracketing, resetting falls and remaking joints extends the life of cast iron and good-quality systems considerably.
Is seamless aluminium guttering worth it?
On long runs it removes the joints that usually fail, and it comes in profiles suited to both modern and period elevations.
Do overflowing gutters cause damp?
Very often. Repeated soaking of a wall face and saturated ground next to the foundation is one of the most common causes of internal damp in older houses.