How to Seal an RV Roof Vent (Lap Sealant Guide)

A leaky roof vent is one of the most common RV roof problems — and one of the easiest to fix with the right lap sealant.

What you’ll need

  • Forever Extra Leveling Lap Sealant (or Forever lap sealant)
  • Clean cloths and water (no harsh chemicals)
  • Caulk gun
  • Optional: RV Roof Man fabric tape for larger gaps

Steps

  1. Clean and dry the vent base and surrounding membrane. Dirt and moisture kill adhesion.
  2. Inspect for cracks, lifted sealant, or holes. Patch larger openings before sealing.
  3. Remove failing sealant if it’s loose or crumbly. Leave sound sealant alone.
  4. Apply Forever Extra Leveling Lap Sealant in a continuous bead around the vent flange, overlapping onto the roof membrane.
  5. Tool the bead so it fully encapsulates the flange edge — no thin spots.
  6. Cure per product guidance before heavy rain exposure.

Pro tip

Extra leveling formula is built for deeper voids and heavy build-ups around vents and skylights. For vertical sidewalls or moldings, use non-sag sealant instead.

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