How do you prevent dew inside your garage?

[The motor guy]

Well every piece of iron in my garage is sweating ... since it went from 40 degrees to 65 overnight. Kind of strange because imo it wasn't that big of a jump. Anyways, I would think if it had an electric heater to warm it up a couple degrees that would help things out, but would a simple dehumidifier work to just keep the humidity level down? We have a ton of humidity even in the winter on the gulf coast. That would be way cheaper than heating. Opinions? The garage itself isn't sweating other than the concrete floor in a couple areas.

 

[97K15004WD]

commercial dehumidifier would be my choice

 

[zfasts03]

I run a dehumidifier in my garage set to 50% max humidity.

 

[jhellwig]

Air movment.

 

[burbguy82]

all of the above, or a space heater to dry the air and raise the temp.....

 

[The motor guy]

Does this not happen in the summer when everyone keeps their house at 68 degrees when it's 100 outside because the hvac system controls humidity?

 

[clinebarger]

I have a pole barn type garage built out of drill stem & R-panel with no vapor barrier in my backyard & it sweats like crazy!

The shop I built in 2019 has vapor barrier under the slab, And the walls/ceiling are spray foam insulated....Neither the exposed steel or concrete sweats.

 

[The motor guy]

I have a pole barn type garage built out of drill stem & R-panel with no vapor barrier in my backyard & it sweats like crazy!

The shop I built in 2019 has vapor barrier under the slab, And the walls/ceiling are spray foam insulated....Neither the exposed steel or concrete sweats.

I thought rigid foam board was a vapor barrier?

 

[Nick1994]

Phoenix.

 

[KrisZ]

I thought rigid foam board was a vapor barrier?

That’s insulation. A vapor barrier is a plastic sheet stapled tightly to all the joists to keep the outside air from entering the inside.

It looks like this

 

[The motor guy]

That’s insulation. A vapor barrier is a plastic sheet stapled tightly to all the joists to keep the outside air from entering the inside.

It looks like this
View attachment 199909

That's an air barrier. Vapor barrier still breathes slightly now that I got my head on straight.

 

[clinebarger]

I was speaking of vapor barrier under the slab/concrete......

 

[The motor guy]

I was speaking of vapor barrier under the slab/concrete......

Slabs all have that around here. I only get minimal sweating on the slab and I think that's just condensation from whatever is inside dripping off.

 

[The motor guy]

Slabs all have that around here. I only get minimal sweating on the slab and I think that's just condensation from whatever is inside dripping off.

I gave it another look today. It's only the front area where I parked two wet pickup trucks. The back half of the shop slab is dry

 

[Jetronic]

dehumidifier. it will move the air aswell as dry it out, but the capacity to dry drops when it's under room temperature imo. They often go into defrost cycles. But the power consumption is not high, certainly lower than heating.

 

[demarpaint]

Air movement and a dehumidifier should do the trick.

 

[Pablo]

Air movement and a dehumidifier should do the trick.

Sounds like you need some ventilation for sure.

We get it here when really cold and dry for a good while, then the express comes up from Hawaii. Warmer and moister.

 

[demarpaint]

Sounds like you need some ventilation for sure.

We get it here when really cold and dry for a good while, then the express comes up from Hawaii. Warmer and moister.

On humid days I'll open up the garage door about 3" or so which gives airflow through the top and bottom of the door. The window I have bolted shut, unfortunately. Vapor barriers and insulation can be tricky. Over the years I did paint jobs to interiors of garages and occasionally found damaged drywall that had to be repaired or replaced for various reasons. Many times we found dampness behind insulation with mold and mildew, due to the insulation and/or the vapor barrier. Bottom line is care must be taken when insulating or installing a vapor barrier where it is very damp. A dehumidifier and airflow imo in those situations is a must.

 

[Pablo]

On humid days I'll open up the garage door about 3" or so which gives airflow through the top and bottom of the door. The window I have bolted shut, unfortunately. Vapor barriers and insulation can be tricky. Over the years I did paint jobs to interiors of garages and occasionally found damaged drywall that had to be repaired or replaced for various reasons. Many times we found dampness behind insulation with mold and mildew, due to the insulation and/or the vapor barrier. Bottom line is care must be taken when insulating or installing a vapor barrier where it is very damp. A dehumidifier and airflow imo in those situations is a must.

Interesting.

The very slight condensation on my shop pad is not coming up from the ground, it's just the concrete is so bloody cold, then warm moist air creeps in eventually. I have a couple 240V electric heaters set on the lowest setting seem to do the trick. Our last house was nasty though. One side had a kneewall with wet earth on the outside......

The attached (to the house) garage does not do this. Two freezers, fridge, heater, water heater, mechanicals, other stuff and master above plus attached walls and breezeway wall keep our garage at a nice even cave temperature but zero condensation.

 

[BMWTurboDzl]

Well every piece of iron in my garage is sweating ... since it went from 40 degrees to 65 overnight. Kind of strange because imo it wasn't that big of a jump. Anyways, I would think if it had an electric heater to warm it up a couple degrees that would help things out, but would a simple dehumidifier work to just keep the humidity level down? We have a ton of humidity even in the winter on the gulf coast. That would be way cheaper than heating. Opinions? The garage itself isn't sweating other than the concrete floor in a couple areas.

A dehumidifier is probably going to burn as many electrons as heating but it will add sensible heat to the garage. I would just pop a window or the garage door.
Cold air is drier