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Condensation on Carport Ceiling

theotherman's picture

A condo owner asked me to look at mold stains on his carport ceiling. The condo is a corner unit, on the beach, with a carport underneath the unit. It is open all around and the ceiling is 2 layers of what appears to be drywall, separated by 1” thick metal furring strips. The resulting cavity is uninsulated. The exposed layer of the ceiling is moist and has large mold rings. The upper layer is dry and shows no signs of moisture. There is a large amount of condensation on the ceiling, even in cold weather. Checking the other units, they all show the same construction techniques and have the same moisture problems. Each unit has numerous sprinkler pipes suspended from the ceiling as well as electrical and water pipes attached.

I am working on the assumption that this is a condensation problem since only one layer of the ceiling is affected. Tearing down each ceiling, even one layer, is a huge and expensive proposition because of the mechanicals and the fact that the units share a common ceiling, separated by walls built after the initial construction. The carports are 12’ x 32’ and there are 25+units.

My thought is by adding some vents to the ceiling, I could increase the airflow and perhaps reduce the moisture by equalizing the temperature. The cavity between the upper layer of the ceiling and the living space is insulated.

Am I on the right track?

Thanks for your help….

(post #113869, reply #1 of 4)

Sorry, you are 100% on the wrong track.

The dual layer is to satisfy firecode requirements. Cutting in a vent will do nothing at all to help solve the problem and will void the code and could subject you to fines and liabilities.

And it will let that damp air into the sopace where you cut the vents in so it collects in the floor above instead, posssibly leading to mold growth and more liabilities.......

Lets work on solving the problem instead of just moving it to another place.

You have moist air coming from the beach
You have more moist air coming out of the exhausts of autos
In the shaded carport, the ceilings are cool surfaces where the moisture condenses out of the air.

so, you could move the bulding away from the moisture...
Nope, that won't work - too expensive and then people would have to walk further to get in their cars.

Maybe you could move the moisture away from the building...A little tongue in cheek but employing fans to move the air around will help.

And you could use some method to warm the ceiling panels enough that moisture doesn't condense.
That would add cost to operate too, but if beach dwellers want to be rid of mildew, they gotta pay for the priveledge.

or - you could make that surface a firecode approved waterproof washable surface and hose it off or power wash it occasionally. Throw in a carwaash for all those convertables parked therein and you've hot the jackpot.



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(post #113869, reply #2 of 4)

Thanks Piffin for steering me right. The car wash idea is a good one. However, hanging any type of additional panel will be a nightmare because of the exposed mechanicals. Fans may be an option, although expensive and unsightly, not to mention the human factor of turning them on. Your suggestion to apply some sort of washable surface seems to be the most practical. Any suggestions for what to use that could be sprayed or painted on. The exposed mechanicals make it a bear to add anything to the existing ceiling.

I will send you your consultants’ fee as soon as I collect one myself!

(post #113869, reply #3 of 4)

How about just one of those exterior grade beach-themed ceiling fans, set to up-wash, kept on low, and running forever (no light kit)

Might even be pretty

Forrest - ceiling fans stir the air, cigar smoke a'swirl - fragrance on the pillowcase, and he, thinks about a girl . . .

(post #113869, reply #4 of 4)

Go to the Sherwin Williams pain tstore and find the most experienced guy there to ask about a coating you can spray on. For a job this big they might even formulate something. You'll want a fungicide in it.

Remember with all painting - prep is everything, so you'll have to get it clean and dry to do the spray job.



Welcome to the
Taunton University of
Knowledge FHB Campus at Breaktime.
 where ...
Excellence is its own reward!



Oh Well,

We did the best we could...