Moisture in the garage

[RICKWHIP]

Hello Everyone,
This is my first post on this forum and I do apologies if this issue has been brought up in the past.
This fall I built a 40X55 attached garage to our house in SW Minnesota.
Here’s the details of it…
-insulated concrete
-floor drains under each car stall
-2x6 insulated walls with vapor barrier and Tyvek
- a Hot Dawg ceiling hung heater
- we keep the space at 55 degrees
- 4 10X10 overhead insulated doors
-2 8-foot ceiling fans

The issue we are having is that the concrete isn’t drying very fast after a car melts off. We also have lots of moisture on the garage doors (interior side). Lastly is very feel moist in the space.
Is this normal due to snow melting off 2 cars daily?
Do I need to put a dehumidifier in there?
Any help / advice would be greatly appreciated!
Rick

 

[Robby321]

Wood stove...

 

[65ranchero]

Gas fired can contribute to the humidity level and with a tight garage no fresh air?
Maybe?

 

[BukitCase]

65ranchero brings up a good point - Need more specifics on the Hot Dawg; electric or gas fired? If gas, is it external vent?

ANY gas or liquid fueled heater needs to be external vented (with a heat exchanger) or it will put nearly as much moisture into the space as the amount of fuel it burns.

If you keep the space at 55, a dehumidifier will help; below about 40 degrees they dont work much. but unless you like emptying the pot a few times a day, it would need a plumbed in drain (or at least a hole in the wall for a garden hose)

Please post the model # of the Hot Dawg, or better yet a link... Steve

 

[RICKWHIP]

Hi Steve

The Hot Dawg is a gas fired unit the is vented to the outside.

It's a 125,000 BTUs
Model Number is: HD125as0121FBAN

thanks again! Rick

 

[DTE]

A dehumidifier would help but the room temp would need to be higher, probably above 60 or so for it to pull water out of the air.

 

[BukitCase]

Rick, good deal; your heater isn't the problem (other than the fuel bill :=)

Dehumidifiers - they do make low temp versions;

https://hvactraining101.com/low-temperature-dehumidifiers/

I have a Frigidaire 50 pint "low temp" that works OK at around 45-50 - it IS slower at lower temps tho... Steve

Oh, for the condensation it's amazing how much it helps just to keep a fan circulating the air - I have a couple areas where roof frames are 2" square tube with fiberglass over (no insulation) - if I don't keep a 30" pedestal fan aimed upward, I get wet lines under the frame tubes every time the weather changes...

 

[Will Allen]

The fact that your garage is new and was built late in the year is also a factor. There is a lot of moisture in your concrete, wood, etc.

 

[XS29L9B]

Rick, good deal; your heater isn't the problem (other than the fuel bill :=)

Dehumidifiers - they do make low temp versions;

https://hvactraining101.com/low-temperature-dehumidifiers/

I have a Frigidaire 50 pint "low temp" that works OK at around 45-50 - it IS slower at lower temps tho... Steve

Oh, for the condensation it's amazing how much it helps just to keep a fan circulating the air - I have a couple areas where roof frames are 2" square tube with fiberglass over (no insulation) - if I don't keep a 30" pedestal fan aimed upward, I get wet lines under the frame tubes every time the weather changes...

+1 for fans to keep air moving (lowers dew point??) and the garage dry.

 

[Showkey]

We have talked about this dozens of times. Bringing two cold snow and ice covered dripping vehicles in the garage every night, have them thaw completely and then try to manage the gallons of water on the floor is a BIG ask.

Push that water out the door or down the drain every night is the only answer. Even then the humidity will still be high. Moving Air witha fan evaporating the water and then catching in the dehumidifier is waste of energy and time......especially every night. It’s a never ending battle. Remove the vehicles from the equation problem solved. Humidity at 39%





Water on the floor and high humidity in garage that used in a winter climate is just what it is.

Adding heat will help in humidity control.....slightly......but It will make more sauna like

 

[ericm]

Do I need to put a dehumidifier in there?

Yes.

 

[ezridr60]

+2 on fans. Ive got a 2 stall here in Frostbite Falls. I've got a Garage Guy heater that's only used if I need to work on a vehicle. Used to get really damp, put in a ceiling fan, problem solved.

 

[Espo77]

Hello Everyone,
This is my first post on this forum and I do apologies if this issue has been brought up in the past.
This fall I built a 40X55 attached garage to our house in SW Minnesota.
Here’s the details of it…
-insulated concrete
-floor drains under each car stall
-2x6 insulated walls with vapor barrier and Tyvek
- a Hot Dawg ceiling hung heater
- we keep the space at 55 degrees
- 4 10X10 overhead insulated doors
-2 8-foot ceiling fans

The issue we are having is that the concrete isn’t drying very fast after a car melts off. We also have lots of moisture on the garage doors (interior side). Lastly is very feel moist in the space.
Is this normal due to snow melting off 2 cars daily?
Do I need to put a dehumidifier in there?
Any help / advice would be greatly appreciated!
Rick

You can test the level of moisture in the concrete slab by taping down a piece of clear plastic...10”x10”. Check it later to see level of moisture beads of water .
Or you could purchase one of those spiffy digital laser guns that would certainly help. If the issue is foundation improper grading, and you have water coming up from there, a dehumidifier is wasting time. Lack of insulation in the garage walls and ceiling’s will make it hard to dehumidify as well. An all around Good hvac system should heat, cool, and dehumidify. Sealing the concrete is something to research .

 

[Showkey]

For the guys not heating and think they have the humidity “solved” couple of things :

Humidity levels are relative to the indoor temperature. As we speak currently 12* F with 84% relative humidity outside the garage. Inside the unheated garage it 40* F 75% humidity. Unheated 40* 70-75% is of little concern for most but far from solved.
If it was heated like the shop it’s currently 65* F 35% humidity.

In the summer ventilation maybe your friend on some days. Other days not so much if 80* and 55% humidity outside. While most days the closed shop with no AC might be 60*-65* F and 75% humidity which is much more of a concern. Prolonged humidity levels above 70% in the closed shop will promote mold, mildew and bad smells on all organic materials first noticed on leather, rubber, paper, card board, cloth and wood. 70-80% in the winter is less of a concern. Ventilation or air exchange is not the answer as the fresh air might actually make the humidity problem worse. As for fan they may evaporate the water off the floor but it still in the air.

Measure the humidity before you conclude problem solved. In a home where winter humidity might be low, a kettle of water on the wood stove is meant to increase the humidity to a more comfortable level. Evaporated water off the floor is the kettle of water. Making humidity rise in the garage. Push the water out or down the drain !!!! The floor drains makes the problem far easier to manage but it’s still a lot of work every day, day in, day out.

 

[rossddvm]

I am in Northwest Iowa so similar climate. For our 2.5 car garage with 2 daily user cars in it turning the heat up to 52 from 45 has helped a lot. If there is much snow on the vehicles I try to go out after an hour and sweep water to the floor drains [our floor was not sloped to the drains properly] I do run a regular dehumidifier and it will pull a gallon and a half of water out every 12-18 hours when the floor is wet. I drive on gravel roads a lot so mud and sand build up on my side fast, scooping that out helps. It is something that takes daily attention this time of year to not have 90% humidity and lots of condensation.

 

[TractorJeff]

FWIW: My Shop floor is flat, I use a GE brand Dehumidifier from Walmart while keeping the temperature above 52 degrees. If it is snow/ice covered, I go out after an hour to sweep out the Slush.

 

[50pascals]

+1 for fans to keep air moving (lowers dew point??) and the garage dry.

A technicality here - Moving air around does NOT lower dewpoint (a property of the air). It can raise the temperature of the condensing surfaces above dewpoint, thus preventing condensation.

It does this by reducing or eliminating a thin layer of stagnant air against these surfaces.

 

[JRC3]

Agreed on trying a fan first. The concrete will dry but I wonder how much it will raise the humidity. It is the first step and simplest thing to do. K.I.S.S.