Moisture

[jante76]

Happy new year all.

I have a 22x22 detached garage with a hip roof. No ceiling. I'm just outside of Chicago.
The walls are insulated and drywalled and painted with a quality paint. The roof has faced insulation in the rafters, and the garage doors are insulated.

I have a mr heater natural gas heater in there and keep the temp at 50ish all the time unless I'm in there in which case I turn it up a bit.

I installed a little ceiling fan at the peak of the roof to blow the air down and keep some air moving all the time.

There are soffit vents but they're covered by the insulation, and the one roof vent was covered also.

This is the first year I've had heat in there. I pulled both cars in for the night, both wet from the snow. I went out about an hour or so later and noticed condensation on the glass for the entrance door. I didn't really notice condensation on anything else. Just the door glass and the window, but it was noticeably a tad humid....obviously.

I was just wondering if it's normal with all the water on the cars in there at the moment and will dry out, or if there's some kind of a venting I ssue that I need to address. I'm slightly paranoid about mold or rot.

If I've left any pertinent info out let me know.

Thanks in advance.

 

[nadogail]

The moisture condenses on the cold Windows, insulate them.

 

[CombatNinja]

The natural gas heater is raising the humidity as well. Water is a byproduct of the combustion process.

 

[rossddvm]

Lots of water in the form of snow sticks to the vehicles. I put a dehumidifier in my garage and it helps a lot. After driving both vehicles in the snow and having floor drains I typically still have to empty the 1.5 gallon bucket 4 times to get humidity below 50 percent

 

[Jlbc212]

Moisture in the air will condense (turn back into a liquid) on any surface below the dew point temperature of the air. That surface could be window glass, the evaporator coil in a dehumidifier or air conditioner or the interior side of the sheathing on a roof or exterior wall. That's why a vapor barrier on the heated side of insulation in a cold climate is a necessity.

 

[Showkey]

The natural gas heater is raising the humidity as well. Water is a byproduct of the combustion process.

That only true if the heater in unvented.
Adding heat will actually lower the relative humidity. If a vented heater is in use.

OP is fighting multiple issues:

1. the vehicles are bringing gallons of water in each day.
2. Sounds like the garage only has marginal insulation.

The ice and condensation is normal under these conditions. Fan will only marginal help. Venting the humidity will vent the heat which is counter productive.

Get the water off the floor, floor drain would be best but not practical unless planned for in new construction and allowed ( permitted).
Guys talk about shop vac the water, a lot of work and a mess.

There are multiple prior posts on running a dehumidifier:

1. High cost of operation
2. Your trying to remove gallons of water each day
3. Most dehumidifiers are rated for 50* at that temperature they are not efficient and spend a lot of time in defrost mode.
4. Opening the doors 2-6 times per day means the air exchange rate is very high. So counter productive to controlling temp and humidity.

Current prior post on garage dehumidifier use:
https://www.garagejournal.com/forum/showthread.php?t=470807&page=2



Bottom line it’s a losing battle if the garage is used daily as vehicle storage that’s coming and going.

To control humidity your must have control of the temperature.

A shop without vehicles coming and going, the venter heater, good insulation and well sealed the humidity will be in the 30% range with no extra effort or cost.

 

[jante76]

Thanks showkey.

I have A floor drain, but my garage is on an old slab that isn't exactly level and the majority of the snow/water goes to the front of the garage, and not to the drain. I'm not sure how I can remedy that if it's even possible since that's where the tool boxes and the storage is.

Thanks for the info. I will read up on the dehumidifier post, but it doesn't sound very promising.

 

[kbs2244]

humidity will follow heat
you need to "waste' some heat by venting it

 

[jante76]

humidity will follow heat
you need to "waste' some heat by venting it

Vent it like as in all the time or vent it by opening the door for a bit when it's bad?

There is a small roof vent that is covered, but I could uncover it. Sorry for the stupid questions.

 

[Showkey]

Venting is not productive.........better example:

Summer in August 98* with 80% humidity outside the home AC has been working hard but can’t keep up. It’s 82* in the house with 62% humidity. Would it make sense after you spend the last 24-48 hours conditioning the air in the home to now open the door and place a box fan in the opening?

Same applies to the garage, controlling the air exchange rate and temperature in the garage is already tough as the doors are used frequently and the the typical garage door is not easy to seal and not insulated to the level of the walls and ceiling.

There maybe a few days were the outside air is “better” than the inside where ventilation works. The full venting is theory metal farm building is frequently used as controlled exchange and temperature is really impossible.

 

[TractorJeff]

OP doesn't specify if the Mr Heater is vented or not?
Squeegee the water to the floor drain.
This will reduce the quantity.

 

[Jazz1]

All that moisture on cars has to go somewhere, I never park a vehicle packed with snow in my garage,,too much of a mess. Floor drain was not really a option when I built as this would have required a in ground tank etc to meet environmental rules

 

[LS6 Tommy]

The natural gas heater is raising the humidity as well. Water is a byproduct of the combustion process.

Only if it's ventless. Most of hte bigger ones are vented, so the moisture all goes out the stack. There's no increase in RH. I wouldn't use a ventless in any permanent installation.

Tommy

 

[doorfx]

A garage containment mat works awesome. No mess in the garage.

 

[kbs2244]

a no cost experiment would be to leave the door open one inch overnight and see if he still gets the frost

 

[jante76]

@showkey, that makes sense now. Thanks for the explanation

@doorfx that is really cool. I didn't even know something like that existed. I am going to look into getting a couple of those. That would keep most if not all the water from running to the front of my garage and sitting there til it dries since it's next to impossible to get to the water once it's against the wall with my toolboxes and cabinets there.

The condensation was gone from the window by the next morning, and most of the water had dried. Most of it.

 

[Loose Nut Buster]

Just another thought!
I have a similar situation in mine with no drain and a slush mess most of the winter on my non even floor.
I went to my local Depot big box to thier electrical dept, they have a vinyl cord trip cover about 2+ " wide x 3/8" H X length ? 16-18' coiled in a box that links similar to the edge of that containment mat, i just snap a chalk line on the floor and using "good" construction adhesive after thourally cleaning the floor ( a house is only as good as its foundation) run a zig zag strip of adhesive the length, have the vinyl strip next to it upside-down, then slowly flip it over along the chalk line, weight it near the end keeping it to the floor for a day or so. Thats it.... water containment and easy to squeegee out and a dry area to walk on all for about 20.00 x 2 since I put it on both sides of our car, works great, 3 yrs n counting. Unrolling & leaving it in the house for a couple days helps relax the vinyl.
Good luck

Sent from my SM-T387V using Tapatalk

 

[jante76]

Thanks loosenutbuster. That's a great idea!!

 

[firebirdparts]

If there are puddles of water in the floor, then the air in the garage will get humid as much as it can, at whatever temperature it is. FWIW. If the garage is good and tight, you should see condensation on surfaces colder than the floor.

Draining the water out certainly helps. If you are running an unvented heater, that certainly hurts.