This 14 year old roma tile power wash we took on this week was in dire need of a cleaning. The north face also had fir trees fairly close so it had heavy moss and debris as well. With the heavy debris and moss we found that the valleys were packed with silt and debris and in need of a more thorough cleaning. We spent time after cleaning to remove the sediment and silt out of the valleys to allow proper flow. Failure to clean the valleys out properly will lead to leaks. Once the valleys are totally clogged the water will divert around the valley flashing and drain off of the metal onto the felt under payment beneath. We have seen a fair number of catastrophic leaks due to valley blockage. Ideally the homeowner we would also have trimmed the tiles back to create a wider channel down the valley so debris would be less likely to block the valley and it would also facilitate cleaning in the future. Long story short, this roof is now much less likely to have a leaky valley, but we have strongly recommended treatment and blow offs more frequently. We recommend every other year for treatment under normal circumstances and a blow off as needed to prevent the debris from blocking the valley and decomposing in the valley under the tiles.
