Mushroom Vents on roof leaking.

[Kiwi Cougar]

I've just found I have water damage in my roof around the Mushroom vent. Two Mushroom vents and two lots of water damage both around each vent. Very disappointing considering my Cougar MLS is 2022 model. I noticed water damage in the bedroom ceiling as the ceiling material had gone soft and deformed. I removed an AC air vent in the ceiling and cleared away the insulation and could immediately feel the wetness and after taking out some ducting could see the wet roof timber and ceiling material all around the Mushroom vent.
It seems to me that rain water gets blown up through the vent and into the ceiling cavity where it just sits rotting the roof timber panelling and the ceiling panelling with no drainage.
I have taped up the mushroom vents as a temporary solution and now are drying out the ceiling cavities.
Hopefully the roof panelling timber is not terminally damaged.
My initial thoughts is to remove the Mushroom vents permanently and patch the holes.
Any feedback and solutions and has anyone else discovered this issue.
Regards Reece

 

[NH_Bulldog]

The way the attic vents are constructed, I don’t see how water can possibly get in and damage the roof sheathing, have you looked into other possibilities? What is your normal roof inspection and maintenance schedule (inspect, reseal etc.)? Keystone recommends doing this every 90 days or so throughout the life of the camper. It is very possible that water is entering a different area and manifesting itself at the attic vents. I suggest doing a very thorough and detailed roof inspection, caulking with a compatible self-leveling sealant and looking for other possibilities.

I would strongly discourage blocking or removing the vents. They are there to provide ventilation to the ceiling space and prevent moisture buildup. Without those vents the water leak (wherever it is really coming from) would create jungle-like conditions in that space and you WILL have a munch bigger issue.

 

[Badbart56]

Call your insurance company. My Fuzion developed a leak around the rear A/C unit and I didn't know it for probably a year and a half or more. We hadn't been in the RV in that long but pretty sure it was caused by a rotten tree branch falling on the roof that far back. By the time we discovered it we had mold in the ceiling.

 

[Martian-KEY]

When was the last time you refreshed the caulking on the roof? I would suspect caulking before the vents as you would probably be the first person that ever reported water intrusion from the vents themselves.

 

[Kiwi Cougar]

My Cougar is only 3 years old so I'm confident the caulking is in good condition as a year ago I covered all my caulking with Eterna bond tape. As I said I have good visibility into the ceiling cavity through an unused A/C vent and the only wet area is definitely around the Mushroom vent. The roof material is in good condition and there are no signs of defects or deterioration anywhere. I regularly wash down the roof.
Maybe I have unwittingly squirted water in it when previously washing the roof using a hose.
Do these vents come apart ? Can you unscrew the outside mushroom cap?. Does anyone know
Thanks Reece.

 

[JRTJH]

You may have a damaged attic vent... If it was "hit by a branch or limb" in the past, it may have cracked the base part of the vent with no damage to the actual top cover. If so, any water flowing around the vent may be leaking into the RV through the crack. A "casual inspection" of the vent probably wouldn't reveal a crack "hidden under the cover on the base"...

That said, the covers typically unscrew from the base on the attic vents. On plumbing vents, they usually "snap off" and quite often "won't go back on without glue or a new cover.

Here's photos of the RV attic vents and the plumbing vents so you can see the difference. I'd pull the cover and check closely around the mounting flange on the base...

 

[jxnbbl]

Interesting enough...I've never thought of this. The only vents I have on my trailer are true vents for plumbing (2 of them). when installing my 2nd AC I had to remove a vent that was on the roof...since it was in the footprint of the AC I was installing. When removing it....there was no hole just a vent (looked like a plumbing vent screwed to the roof). Do all trailers have "attic vents"?

 

[Kiwi Cougar]

Hi guys today I discovered where the water is getting in. After removing the tape from around the mushroom ( a temporary fix to stop anymore water getting in ) and looking out from the inside, I could see a crack in the plastic riser pipe underneath the mushroom cover . The crack was opened up enough to let in water.
On inspection of the 2nd Attic vent there was a crack in the same position. Too much of a coincidence so I would guess they're been cracked on installation. Perhaps hit into too tight a hole into the roofing chipboard on the production line. Something like that wouldn't surprise me.
Any thoughts on that?