Cinder Block Garage Ventillation

Old 01-05-22, 04:18 PM
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Cinder Block Garage Ventillation

So new to the forum, searched the internet to no real avail. Seems like there are camps with different opinions, etc on the subject so taking a shot here.

I recently purchased a new home that came with a painted, slabbed, cinderblock detached garage (24x24) that is mildly shaded. The old house I lived in was an attached finished garage. I am a wood worker and have full on wood shop, also worked in aviation for some time (so lots of tools) and my own vehicles, pretty much do everything myself, car, house, etc. In the old house I rarely had to wax my cast iron but in the new place I have noticed my untreated workbenches (wood) starting to grow mold and my cast iron woodworking machines forming surface rust. I have since liberally sprayed Beolube on everything and bleach spray on any moldy wood surface to slow down this effect as I work towards a solution.

The garage has a hip roof with a ridge vent but no ceiling I noticed that the roof framing and sheeting is mold free. They seemed to had started on installing soffit (2x2) ran around perimeter of the building but no soffit has been installed. The inside and outside is painted with what is seemingly a high quality moisture proofing paint so I see no evidence of moisture coming through the walls and the slab has been sealed but I have not yet done a moisture test.

My question:
I really don't need the space to be conditioned, I am very temperature tolerant on both ends of the spectrum and a fan is really all I ever need to stay cool in the summer. From what I have gathered online I need to reduce the humidity, especially in the winter and that by installing ventilated soffit, finishing the ceiling and insulating the attic space that should be sufficient in reducing the humidity inside since as of now without soffit and a ceiling cold and moist air is being pushed up into the garage from the eaves. And if that only helps some then purchasing a dehumidifier would also help bring down the humidity in the space once I do the above. Am I on the right track here? I am just trying to protect my tools and machinery but if I have to, in the long run I would not be opposed to fully insulating the space and installing a split AC but as I said before a fan is good enough for me in the summer and pants in the winter to tolerate the temperature so if I don't have to I rather not. My primary goal is to not have to worry about mold and rust due to static moist air. Also read someone just installing a ceiling and running ceiling fans was enough to prevent mold growth, he had the fans pulling air up to vent out of ridge vent.

Any input would be appreciated especially those in Northwest Florida with similar battles. I apologize for the long winded post, any input/ advice would be appreciated.

Old 01-05-22, 04:32 PM
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My guess would be that this is simply a problem of the garage temperature being lower than the dew point is. It's a daily problem because the garage gets cool, then holds the cool in, longer than normal since it's in the shade. That causes everything to sweat when humid exterior air either seeps in on its own or is introduced by opening a door.

I'd probably just suggest a large exhaust fan (biggest louvered fan you can afford) that circulates exterior air into the garage 24/7... or at least during the day. It will make the garage warmer, but by doing so, the air movement plus the higher temperature should solve the condensation issue.

I doubt the problem has as much to do with roof ventilation... and simply installing a roof fan or more roof ventilation won't help. The problem is below the ceiling.

And I'm not sure that a dehumidifier (instead of the exhaust fan) would help but it wouldn't hurt. You'd need the biggest one you can get, and have it pump the water outside or to a drain inside.

Is Beolube better than T-9 Boeshield on the cast iron?
Old 01-06-22, 06:29 AM
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I need to reduce the humidity, especially in the winter
Depending on where you are located the winter humidity is typ not an issue.

As XS noted the worst time of the year for cold winter climates is spring, when the garage, the floor, all the tools are cold and you get those early warmish humid days and everything gets coated with condensate.

Truly, the best solution is to have a conditioned space or something close.

In prior homes I had fully insulated attached garages and with that little bit of heat from the house I never had any spring issues. With my current non-insulated attached garage it can get wet in the garage.
Old 01-06-22, 11:05 AM
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Is Beolube better than T-9 Boeshield on the cast iron?
No, I typed the wrong thing out, I use Beolube for drilling metal as a lubricant. I actually meant to type T-9 Boeshield. But honestly, I typically use Minwax Paste Finishing Wax to protect the cast iron on my machinery. I just had T-9 laying around so I could quickly just coat everything before any real rust took hold.

I will have to take a look at different fan venting options for the hip roof I have. In whether or not venting from the side of the building or roof. I do live in a hurricane-frequented area so I will have to take that into consideration, I feel like venting out the building side would be a better choice.

​​​​​​​In prior homes I had fully insulated attached garages and with that little bit of heat from the house I never had any spring issues.
Makes sense. The house I moved from had an attached garage with two walls insulated and one wall not insulated nor was the attic space insulated and I never had any issues. I think I will take a look at implementing XSleeper's suggestion and also get a material cost quote to condition the garage. I am about to upgrade the subpanel to get 240 power to my cabinet saw and compressor as the garage only has wiring for lights, a few 120 outlets, and the garage door opener. So I will have to add a split AC unit in the equation in case I do take that path down the road.

Thanks for the replies.


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