Blocked cement valley prevents drainage

During a recent Building Survey carried out on a 3-bedroom detached house in the North West, it was noted that there was a very narrow cement valley to the side of the roof, blocked by debris and weeds, preventing good drainage. In and of itself, this was not a dramatic issue, and could be easily rectified by simply cleaning the valley. Unfortunately, however, it appeared that the blockage had been left unresolved for some considerable time. As a consequence, during periods of even light rainfall, rainwater was not draining correctly, ‘overshooting’ the guttering to create large areas of damp on the outside bathroom wall.

The purchaser was advised to clear the valley as soon as possible to arrest and reverse the damp problem.

Missing or damaged rainwater goods are commonly found on home surveys where gutter junctions have become detached or original cast iron pipes have rusted. One common issue arises where cast iron down pipes have rusted at the back, close to the wall, and are leaking down the wall, causing damp problems. This situation is hard to remedy with the traditional solution of bituminous over-painting, due to the inaccessibility of the problem. In this case, replacement of the affected pipes is the recommended solution.

Leaking gutters can also lead to excessive damp on fascia boards, which inevitably leads to wet rot. Although guttering and rainwater pipes are reasonably cheap to fix, they can lead to more expensive problems if left, and buyers should be aware that the full extent of damp problems caused by leaking, poorly fitted or carelessly maintained drainage may not always be evident during a visual inspection.

Post Author: Frances Traynor