On concrete tile roofs many older metal B‑vents are sealed to the roof tiles with nothing more than roof cement. As that sealant dries out, shrinks, and cracks, it can open small gaps where water runs under the flashing and into the roof system. On tile roofs, this is a common source of slow leaks and stained ceilings.
When we replace these vents, we don’t just add more caulking. We install new B‑vent flashings with a containment lip bent up around the flange. That upright lip acts as a built‑in water stop, directing water away from the vent opening instead of depending on a bead of sealant. The metal flashing stays rigid, the lip keeps water on the surface of the roof, and you get a longer‑lasting, more reliable B‑vent detail with far less risk of future leaks.
