Garage Condensation...Help is appreciated!

Hey all, first post, so thanks in advance for the help.

We just built a house w/ 3 1/2 stall garage, and today for the first time i'm noticing condensation in the garage on the ceiling between sheetrock joints and along wall joints.

Long story short, to save a little $$ during the building process, i opted to insulate/sheetrock the walls, but just sheetrock the ceiling (not insulate). I'm thinking that was a mistake now.

The ceiling is very well ventilated with roof venting & soffit venting. I occasionally use a bullet heater to heat the garage slightly when out there doing projects, etc., and am now thinking that the vapor barrier under the sheetrock is trapping moisture....correct?

Guess my question is about insulating. If i have someone come and blow in insulation in the ceiling, would that minimize the moisture that i'm seeing or not?

It's not feesible for me to constantly heat my garage, but would like to on occasion w/o the moisture build up. Any suggestions on what to do?

Thanks much!

is a bullet heater the same as a propane heater: if so, I believe they put a lot of moisture into the air.

Condensation forms where hot moist air hits a cold surface, which sounds like the lack of insulation in the ceiling is the problem.

Im not sure about garages, but I've got mad condensation in my bungalow (rubbish double glazing), but I;ve read a lot and having good air movement can get the moist air out and fresh (colder - drier air) back in, so, I guess if you installed some fans to circulate air around you might be able to reduce the condensation levels.

You can get humidity sensors that can fire up a fan when a certain level is reached, which will probably be when the heater's on, there's also heat exchanging extractor fans available which remove the warm damp air, feed the heat back into the building along with air from outside, which is less humid (or something like that)

I take it when you have the heater on the garage is pretty much sealed? maybe you can try to leave window/door open a bit for a while after using the heater, let the warm air get sucked outside?

Experimenting with various methods of ventilation worked a bit for me and my house.

I know Menards, and maybe Home Depot, will let you use an insulation blower for free if you buy the insulation from them. Get somebody to dump the insulation into the hopper as you shoot it around the attic. Easy to do, very economical and a great idea all around.

Insulating the ceiling will only cause the condensation to appear at a different location.

your running unvented heater is the sourse of water. You run the heater you produce water vapor, huge amounts of water vapor.

Elimination of the water vapor eliminates the condensation.
Problem solved!

If you are planning on blowing insulation into your ceiling, be sure to purchase a good respirator. Goggles / face mask is also a good idea.

If you are planning on blowing insulation into your ceiling, be sure to purchase a good respirator. Goggles / face mask is also a good idea.

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Been there, done that. Blowing insulation has got to be one of the messiest jobs there is. I have an garage access panel to the house attic and I know I was cleaning dust out of the garage for 6 months or more. And I don't know which is worse job....being the attic guy, or being the guy loading the hopper. DO NOT settle for the cheap paper type filter respirators. Get a face mask type or paint respirator. And like Z07 stated, use goggles. Also wear long sleeves, because I think that you absorb some of the stuff in thru your pores. But for what it is worth, my wife and I did my garage attic in way less time with batt insulation then we did the house with blow in. And as far as batts go, I think it does a better job of insulating and it is way cleaner. If for any reason I have to get into the house attic, I am covered with dust.

Condensation or frost, depending on the temperature, occurs when air is cooled below the dew point. The dew point is the temperature at which air molecules become over saturated with water and can no longer suspend the water in air. The result is condensation or frost forming on surfaces that have a temperature below the dew point. If the dew point is below 32 degree's frost will form, above that temp. moisture will form.

With regard to a garage, if you plan on heating it, keep the heater running at all times and heat it to a temperature above the dew point. This in itself will completely solve the condensation problem.

If you find that you must run your heater at an extremely high temp because the dew point is high, you can lower the level of humidly, thereby lowering the dew point, which will enable you to maintain a lower, more reasonable garage temp. To do this...install a gas heater with a powered exhaust vent. These types of heaters not only exhaust carbon monoxide, but **** the smoke and the humid air out as well. Ensure you size up a heater with the correct BTU's for your garage volume. If it's too big, it will not cycle enough to keep the air fresh, too small and it may run all the time. I have a well insulated 1000 sq. ft. garage with 10 ft. ceilings and use a 75,000 BTU gas heater. I have used it for over 10 years and live in the cold upper Midwest. I maintain a temperature of 62 degree's during the winter months. There has never been one spec of condensation and my yearly heat bills for the garage are only $150.

Another way to lower the humidity is to install a water drain system in your garage that drains the melting snow off your vehicles back into your household drain system. This will help keep the humidity at a lower point, which lowers the dew point, which means you can keep your heater thermostat at a lower value, saving you $$.

Lastly, you will want to conserve energy, (saving you $$) by insulating the garage walls and putting up a water barrier in the stud cavities behind the sheet rock...and most importantly, properly insulating your garage attic with insulation, blocking & venting.

I believe some people have condensation problems because they do not properly follow best known practices or they only turn their heater on when they want to work in the garage.

With regard to a garage, if you plan on heating it, keep the heater running at all times and heat it to a temperature above the dew point. This in itself will completely solve the condensation problem.

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I believe some people have condensation problems because they do not properly follow best known practices or they only turn their heater on when they want to work in the garage.

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Not necessarily true. You should not have to run a heater constantly to keep moisture / condensation down. Especially in the winter when the air is dry anyways. I have never once had any condensation in my garage, winter or summer. In the winter I can leave the heat off, come in, fire up the furnace until it gets to around 70 and have absolutely no moisture problems at all. If you run an unvented heater, especially propane, you will get moisture from that. When the moisture in the warm air meets a cold surface, you will get condensation. Where that condensation forms or settles depends on the construction of the building. What the original poster needs to do (and I realize his post is almost a year old) is to insulate the ceiling so there is not temperature differentials within the confined space. I would not use anything ventless in a confined space anyways all because of the carbon monoxide. If the cold ceiling was eliminated by insulating, as that is where the heat is going to go first, then I would say that most, if not all of the moisture problem would be eliminated.

If you must use an un-vented heater, you have to keep the door up a few inches or have a window open a bit when working.
This does 2 things.
It gives you some fresh air so you don't die
and it gets rid of a lot of the moisture.
Then, when you are done working, open the door all the way for about 30 min.
The moisture will follow the heat out the door.
Are you “wasting” the heat?
Sure.
But you are also drying the place out.

Un-vented heaters have their place.
But that place is as temporary heat in rough construction with lots of air leaks.
Once you tighten a place up, you have to go vented for your heat.

Would this include the propane Buddy Heaters? I have a Big Buddy and it heats the garage nicely, and I've only noticed a small amount of condensation because it is finished all around and now insulation. The Buddy Heaters are made to be run in closed places it says.

Are they the IR ones?
They are not as bad because they do not use as much fuel per hour.
But any combustion makes moisture. and if it isn't vented to the outside then it stays inside.

Clarification...by keeping the heater continuously running, I am referring to having the thermostat in the heat position, not the off position. The temperature setting will (obviously) dictate when the burner is fired up.

True, the winter air is considerably drier, but humidity will build rapidly when snow covered vehicles are parked in a garage with a temperature above 32 degree's.

Once again, the bottom line is that condensation forms on objects when that objects temperature is cooling down the surrounding air below the dew point. Ergo, we must keep that object's temperature above the dew point.

Using various venting techniques will allow you to keep the humidity down, allowing you to maintain a lower temperature setting. Using insulation in the walls & attic will conserve energy. Both of which will save $$.

Yep -- one of the by-products of combustion is moisture -- any heater that burns something, and doesn't vent the combustion by products to the outside, will cause condensation --

I stood the rain forwest micro-climate I created in my shop for 3 years before finally doing it right and getting a heater that vents outside -- a HUGE difference (and kicking myself for waiting so long)