Of all the leak problems we encounter at Anderson Roofing & Contracting, one of the most common is directly related to the venting of the water-heater through the roof.
A homeowner can usually expect to replace their water-heater every 10-15 years and a quick call to the plumber is all many consider. From there, the next and final decision (with exception of the cost) is whether to go back with a traditional water-heater, or upgrade to a tankless system.
Whichever product or system is chosen, there is something else to consider: the roof.
Proper flashing of the water-heater venting is essential to keep water out of the home. Unfortunately, it is frequently done incorrectly. Plumbers may neglect to tell the homeowner further work needs to be performed, with the owner only becoming aware after they discover a leak.
Many plumbers are not equipped to handle the roof scope of work. This is usually due to the steepness and height of the roofs, or lack of familiarity with roofing components. Their knowledge (usually) stops at what type of flashing the roofer should be installing around the vent pipe/duct.
When an existing traditional water-heater is swapped out for a new model, the new water heater may be a different height. Consequently, This will cause the position of collar flashing on the pipe/duct above the roof to become unsealed and unseated. For example, the photo below was taken at a new client’s home in Flower Mound and references this very problem.