After cleaning a house roof it started to leak

Great Outdoors Exterior cleaning was contacted by a customer based in Leighton Buzzard, Bedfordshire as their roof occasionally leaked after severe rain. 

We pressure washed the roof almost 12 months before they started to experience problems with leaks.

This was an old customer for whom we have worked for over 5 years. During this time we had cleaned their roof several times, as it is located in a wooded area and suffers from moss, leaf, and pine needle drop. We have also pressure washed their Indian sandstone paving and block paved driveway.

The only way to determine what was causing these issues was to partially strip the roof tiles, this would enable us to check the tiles for any breakages and inspect the roofing underlay/membrane. Unfortunately, this occurred at the height of the Covid pandemic, as the customer was vulnerable we did not want to enter the property and check in the loft area, for obvious reasons. Hence the roof had to be inspected from the outside only.

We gained access to the roof area using a suitable ladder fitted with a microlite standoff and suitable base support. From the roofline, we could throw over a rope and anchor to the van using a suitable strop. Whilst working on the roof we were harnessed to the rope for safety. 

Starting from the gutter line in the problem area we removed the first row of tiles,  once a few rows were removed and no issues were found we could replace the tiles and continue this process up to the main ridge. Whilst replacing the tiles we used the opportunity to brush and scrape out the drainage channels on the tiles, to aid with drainage.  

After removing and replacing a few rows of tiles we discovered the problem! 

As suspected the leaks had absolutely nothing to do with the roof cleaning process. In two areas wasps or hornets had formed nests under the tiles and eaten through the roofing underlay. During normal rain these holes would not cause any issues, however, during heavy rain, it is possible for the water to creep around the tiles due to capillary action. As the roofing underlay had large holes leaks would occur. 

A common misconception is pressure washing roofs can cause leaks, to be frank, this is complete nonsense. We have been providing a professional roof cleaning service since 2002. We have almost 20 years of experience cleaning roofs, not just exterior cleaning but actually cleaning roofs, during that time we have cleaned over a thousand roofs, washing a house roof with a pressure washer by a skilled professional does not cause leaks! 

Once we discovered the problem with the underlay we set about repairing the roof. We locally removed the battens added new roof underlay, replaced battens and tiles.  Problem solved! 

For more images of this roof repair please click HERE 


Project skills
external link