Metal Roof Vent Condensation in Garage

[SupremePossum]

Looking for suggestions here before I proceed with my plan

To cut a long story short, I have a detached, unconditioned garage in Houston TX. There is zero insulation and no ceiling.

It used to have a plastic roof vent, no problems. Now it has a metal roof vent, and when a storm rolls through, the vent ends up condensing and dripping down.

Personally, I don't think a 2 car garage needs a roof vent.

My plan is to spray the underside of the vent with plastidip and then block off the vent with foam board insulation. This will cause me less heat loss in cold winters too, I would assume.

Stupid idea? Pictures of the vent.

 

[Nukeman7]

My best guess is that you have rainwater intrusion, not condensation dripping from that vent. If the garage is not air conditioned, there should not be enough temperature differential between the inside and outside air to cause condensation to form. Try this, next time you anticipate an approaching storm, go up on the roof with sheet plastic (e.g., large garbage bag) and duct tape to fully seal up the outside of the vent. If it is truly condensation, it will still drip inside the garage. If it stays dry, you have rainwater intrusion.

 

[SupremePossum]

Its 100% condensation, I've watched it many many times

 

[joekingcorvette]

I would take the vent off and attach a piece of metal similar to the vent on a garage heater. I would just use some sheet metal screws and match up new shingles and throw the vent in the garbage can. Make sure you black jack it real good underneath the metal. Use a type of metal that is rust proof.

 

[JTK]

Does it have the proper insulating, weather proof boot installed on the OD of the vent on the outside?

Other than that, I would think warmer, moist air from in the garage would condense against the metal surfaces of that vent as is designed and installed, regardless of the roofing material.

 

[Rand]

if the air inside was warm and moist enough to condense.. you probably want a vent.
I wish my garage roof had a vent.. it vents through a cut out to the breezeway roof then to the main roof.. not very efficient.
I had it covered (fire barrier required! blah blah)and my garage steamed up so much the paint peeled off the ceiling.

Thinking about installing a thermostat switched gable vent fan but thats abit of work.

 

[KrisZ]

You do need that vent, do not block it off. Otherwise your roof will start to rot. Condensation on the vent proves you have humid air inside.

To prevent condensation on that metal vent you need to insulate it. I don’t think plastidip is thick enough though.
Something like a garage door insulation kit would probably work.

Or something like this since you don’t need a whole kit.