The most common asphalt shingle roof leak happening today has to do with T-lock or Interlocking shingles. These are also known as duroid shingles and should not be confused with a metal shingle made by Interlock. Back to the leak issue: Of course, as previously blogged, leaks commonly happen where there is a protrusion or change in direction of the roof plane. However with these T-lock shingles, leaks can show up anywhere. First let’s get a history of this shingle. No longer in production today, this organic shingle was originally sold promoting the feature of wind uplift resistance. It’s my understanding that these shingles were sold with a 20-25 year life expectancy but current evidence details that most roofs in Vancouver and the Lower Mainland area are not achieving that extent. Technically, the unique design of this shingle allows for water to get in behind a corner of the shingle but escape out from underneath, lower down on the shingle. This critical water-entry point is where the tabs or T-Locks interlock with the below fastened shingle. This is all fine and dandy while the shingle is lying flat but as this ORGANIC shingle ages, it becomes dry and curls. It is at that age point the shingle systemically fails. Because of the curling, water will begin to travel sideways…which is never a good idea on shingle roofs…and leaks become inevitable. Because this shingle is no longer in production and extremely rare in ability to acquire, (I found some guy in Richmond BC selling bundles that used to cost $20 for $100 on the internet) roofers are left to try and stop the leak with our magic muck called mastic. BUT, unless the repairing roofer is aware of the “unique” feature of water entry and exit on this shingle design, he could potentially cause more problems than benefit by applying the mastic at the exit point and actually trapping the water under the shingle. If you have a shingle roof leak and want the best in service, contact Crucial Roof Services where “Your Satisfaction Is Crucial”.