A drip from the bathroom fan feels personal. You're in the smallest room in the rig, you look up, and dirty water lands on your head from a vent that was fine last season. That fan can leak three different ways, and each one has a different fix. Seal the wrong one and you'll be back up there after the next storm.
I've chased this exact drip on a lot of rigs. Sometimes it's the lid. Sometimes it's the flange seal underneath. Sometimes it's just the lap sealant on top that's cracked and done. Here's how I tell them apart.
First test: does it leak when it rains, or when you shower?
Start inside. If the drip shows up during or after a shower and the roof is dry, you may not have a roof leak at all — shower steam hits a cold vent, condenses, and drips back down. That's annoying, but it's not rot. Run the fan while you shower and see if it stops.
If it drips during rain, especially wind-driven rain, or you find a stain ring on the ceiling around the vent garnish, that's real water coming through the roof opening. Now go up and meet the three suspects.
Suspect 1: The lid
The plastic lid lives in full sun, and Florida sun eats it. Look for cracks around the hinge and lift-arm bracket, chalky brittle plastic, and corners that flex when you press them. A cracked lid lets rain straight in — sealant on the flange below it won't matter.
If the lid is the problem, replace the lid — nothing else. The opening is a standard 14 by 14 inches on most rigs; what differs is the hinge style, so match yours before you order. A Camp'N 14-inch universal replacement lid fits many Ventline vents built before 2008 and Elixir vents from 1994 on. From inside, drop the garnish and screen, disconnect the lift arm, then slide the old lid off its hinge on the roof.
Suspect 2: The flange seal underneath
This is the real seal, and the one nobody sees. The fan flange sits on the roof bedded in butyl tape — that butyl is the gasket. When it dries out or shrinks, water walks under the flange, through the screw holes, and into the ceiling, even when everything on top looks sealed.
The tell: the lap sealant on top looks decent, the lid is sound, and it still leaks. Or you can see the flange edge lifting, or rust bleeding from a screw head. There is no surface fix for a dead flange seal. The fan has to come up and get rebedded.
Suspect 3: The sealant on top
The lap sealant over the flange edge and screw heads is the second line of defense, not the first. Check it for cracks, splits, pinholes, and peeling edges. If the butyl underneath still works, a leak here is usually slow — staining first, dripping later. This is the one suspect you can fix from the surface, if you prep it right.
Prove which one before you fix anything
On a dry day, have someone inside watching while you wet one thing at a time with a hose, low pressure, a few minutes each. Start with the lid closed, wetting only the flange perimeter. Then wet the lid itself. Whichever step starts the drip is your leak. Ten minutes of testing beats tearing the fan out and finding it was a cracked lid.
Fixing the flange the right way
Power off first. Remove the garnish, disconnect the fan wires, take out the flange screws, and ease the fan up. Scrape all the old sealant and butyl off the flange and roof — plastic scrapers on a membrane roof, never a metal blade gouging EPDM or TPO. If the decking is soft, stop and fix that first; screws need solid wood.
Bed the flange in a continuous loop of XFasten Butyl Tape, 1/2 inch by 30 feet, no gaps at the corners. Set the fan, snug the screws evenly until butyl just squeezes out, and don't crank them — you'll crack the flange or strip the decking. Then cap the flange edge and every screw head with Dicor 501LSW Self-Leveling Lap Sealant. It's made for horizontal roof surfaces — vents and screw heads are literally its job — and it flows into pinholes non-sag sealant bridges over. Never silicone: it fails early and contaminates the surface.
If you're only renewing the top sealant, dig out every cracked, loose piece first. New lap sealant over failed sealant just makes a thicker failed seal.
Mistakes that bring this drip back
- Smearing sealant over a cracked lid instead of replacing the lid.
- Caulking the flange perimeter without rebedding it in butyl when the under-seal is dead.
- Layering new sealant over cracked old sealant without digging it out.
- Using silicone anywhere on the roof.
- Matching a new lid by size only and ignoring the hinge style.
- Skipping the hose test and declaring victory before it rains.
Flange, lid, or sealant — name the one that's actually leaking, fix that one properly, and hose-test it before you call it done. That's how a bathroom fan stops being a recurring drip and goes back to just being a fan. Fix it right the first time.
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