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Garage condensation nightmare - please help!

graham8

New member
Joined
Dec 20, 2022
Messages
1
Hi all

I’m in desperate need of some help, and am suffering full blown anxiety attack over my garage, which has just broken out quite suddenly in pretty extreme condensation for the first time.

So I noticed this morning that everything metal or plastic in my garage was covered in condensation/beads of water and soaking. On top of this the entire floor which has some hard pvc interlocking tiles fitted over the concrete is soaked all over and it just seems to keep building up more and more on the floor tiles in particular. Upon first discovering it I I tried to wipe down what I could as well as the floors. but it doesn’t seems to have helped, the floor tiles for example returned to being wet again within a couple of hours.

I’ve read people suggesting a dehumidifier, so I’ve put the one we have from our house out in the garage tonight and so far had it running for almost 6 hours. The garage floor is still soaked and the air humidity doesn’t seem to have dropped at all (started at 90, still resting at 90) air temperature is about 9 degrees in there as of early hours of the morning/right now. I did tape over the vents and push some plastic wrap under the garage door to try to reduce pulling in outside air where possible though may not have done a great job, and certainly haven’t sealed around the entire door etc, but since 6 hours later and I’m seemingly no better off, can still see new condensation formed on tiles I’d wiped already since humidifier was running, and the humidity is still measuring the same.



As an aside as this hadn’t happened before I wondered - why now? The floor tiles were laid about 14 months ago so have seen a full winter before and so what has changed that could have triggered it? A few things that I wondered if could be relevant:

1. we just had pretty cold weather for a week and snow which stayed present for a few days, followed by sudden rain and increase temps overnight and we currently have generally high humidity to boot (90% outside right now)

2. For the past 2 days I was doing some jobs on the car outside and had the garage door open for several hours on each day (this during rain today, and very cold day yesterday with snow still on ground outside) - not sure if this could have been a catalyst??

3. We had mushroom vents installed a few months ago into the ceilings as the timber roof by the house builder as the timber roof had a little damp/some mold spores that were previously treated after a little damp 2 years ago was noticed on the ceiling shortly after moving in (this seemed to sort it self out and was generally fairly dry for past 18 months, but as other houses on the development had experienced issues the house builder offered to install additional mushroom ventilation in ceiling on all the garages so when offered we accepted on their recommendation.



So a bit of details on the garage that may also be useful . My house is a new build 2.5 years old, and the garage is on the side where it shares about 80% of one side of its wall with the house. It is of single brick construction and shares just the one wall with the house. Up and over door to front and personel door to rear. Two vents to front above door and two to rear at equivalent height. 6 mushroom vents in ceiling. No windows. Wooden flat roof with some kind of plasticy looking coating on the roof (not sure what this really is). It’s a very basic garage. Inside the garage floor sits about 5 inches lower than The ground level of the garden patio and house and there are some areas of the garage internal brickwork that feel a little damp below the dpc. Their is a guttering down pipe that and garage guttering down pipe that run the ground near the rear corner to a soak away that may be contributing to a bit of damp in one area of the brickwork below dpc - but honestly I don’t know.

I’m at a total loss of what’s happened here and why now all of sudden and what to do. I had hoped putting the dehumidifier in there tonight I’d see the levels dropping but they haven’t dropped even by 1% and the condensation is still continuing to build allover the floor tiles. I lifted some other floor tiles and they seem dry underneath.

Appreciate any help and advise, I’m getting seriously stressed out by it, I thought chucking in the dehumidifier would start to bring the humidity down slowly after a few hours, but nothing so far…
 
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jives

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Jan 4, 2013
Messages
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Central NY
Need more information. First, where are you located? What is the normal winter temp, and is 9 deg the "pretty cold"? Size of garage? Insulation? Seems unheated. . . is that true?

The experienced HVAC folks will have a more definitive answer, but I don't think dehumidifiers work well in the cold. You would be better off heating the space.
 

mike93lx

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Joined
Dec 9, 2013
Messages
38,398
Location
Richmond, VA
Dehumidification takes time. Leave it be and add another if you want to speed it up.

In an environment with that level of humidity, I would have a good dehumidifier on all year. 50% set point and give it a drain.
 
Last edited:

gregs

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Joined
Mar 16, 2007
Messages
1,646
"1. we just had pretty cold weather for a week and snow which stayed present for a few days, followed by sudden rain and increase temps overnight and we currently have generally high humidity to boot (90% outside right now)

2. For the past 2 days I was doing some jobs on the car outside and had the garage door open for several hours on each day (this during rain today, and very cold day yesterday with snow still on ground outside) - not sure if this could have been a catalyst??"

This is a 100% your problem. If you are going to open up the door during these particular weather events, you should only do it for the time it takes to get something in or out. It will take a long time to dehumidify the garage.
 

kaymccampbell

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Feb 27, 2015
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29,847
Location
Upstate New York
You've been bad, like @gregs said. The very best dehumidifiers work down into the 40s. Beyond that, you can pretty much forget it. Heat will be your friend here. Get the garage into the 50-60s, the surface beaded moisture will appear to go away. It hasn't, it's just trapped in the air. Then you run the dehumidifier.
BTW, it can take a week, or longer, to undo a couple hours of humidity indiscretion.
 

finn

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Joined
Mar 27, 2005
Messages
16,621
Location
The UP, God's country
Humidifiers ice up at low ambient temperatures and then don’t function.

Heat the garage to reduce the relative humidity. You really need to get the floor and contents above the dew point.
 

racecougar

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Jan 26, 2021
Messages
5,433
Location
Missouri
It sounds like the OP is talking about 9 degrees Celsius, not Farenheit.

It also sounds like the ceiling being referred to is actually the roof.

OP, if the garage is vented to atmosphere as you've described, the humidity level in the garage is going to rise with outdoor conditions.
 

jar944

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Joined
Jul 26, 2010
Messages
6,022
Location
Northern VA
A cold soaked interior and warm moist air will do that, all the time every time.

Seal it up, or heat the space (preferably both) that dehumidifier is not going to do anything as long as warm(er) moist air infiltrates the space AND the interior remains cold.

Also.. are you in England? My ig feed was full of joinery shops that looked like it was raining inside after the recent temp swings.
 

duneslider

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Jan 20, 2013
Messages
2,301
Location
Riverton, Utah
I too am suspecting this is 9deg C which is about 48-50 deg F.

I live in the desert so I don't understand the intricacies of humidity, people around here add whole house humidifiers to run in the winter. The only time a dehumidifier is used is if your house floods and the disaster cleanup people come to clean things up!

I would say that air movement is your friend, get some fans in there moving the air around.
 

John McA

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Jul 11, 2009
Messages
294
Location
Pasadena
Except for not stating your location: Great 1st post!
Great subject! Spot on! Related to garages, garage doors, attached garages.
How long does approx. 3200 cubic ft. take to dry out?
Jump start by renting a big construction heater?
 

crazylunker

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Sep 2, 2014
Messages
198
Location
Connecticut, Trumbull
real simple, just heat the garage, if you keep it slightly above ambient temp it will never condense. and keep the dehumidifier going 24/7 during spring months

My garage is under the house in new england and I have been dealing with the same for over 30 years.
 

gregs

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Mar 16, 2007
Messages
1,646
I'll add that I keep 2 cheap 20" box fans running 24/7/365 in my shop and it aids in keeping moisture from setting on my big tools and causing surface rust. The big machines like mills and lathes take a long time to warm up or cool down, and when you get a big temp swing they become condensation magnets.
 

iadr

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Messages
77
Location
Alberta
Electric heat and only electric heat is what you want to generate warm by. Though it has not been a problem for me I've been warned mightily by member here about using open air, unvented (ie, portable not chimney's) combustion heaters. We had a small fiberglass (Boler brand) travel trailer growing up. We always went to campgrounds with electricity, as the dryness of electric heat made for moderately comfortable sleeping for 4.
Could be worse... you could have frost rather than droplets. ;)
 
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haveissues

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Feb 9, 2011
Messages
379
Location
Hudson Valley NY
My shop isn't heated yet and if we had a cold night followed by rapid warming as soon as I open the garage door everything starts to sweat, even the floor. Warm moist air hitting cold things will do that.
 

Jackfre

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Dec 26, 2010
Messages
4,429
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N CA
This is a real world lesson in “dew point”. Cold air cannot hold moisture so it gets to the DP and, yes, you freak when you find your sockets swimming, not to mention everything else. As Kay said, heat is your friend in this situation along with air flow..
 

Buford T. Justice

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609
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Montague County
I had / have the exact same issue going on. It has gotten better by bumping the heat up as well as running fans in all four corners making a nice circulation pattern so yes, as others have said, do that.
 

Renegade1LI

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Messages
5,058
Location
long island ny
If you can't heat it, ventilate it, get the air moving , you're trapping the moisture. In a non hvac garage the only option is to keep it well ventilated. I have a non hvav garage in the Adirondacks, very humid and same problem, once I added a couple of fans the problem went away. Cheap to try.
 
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Metal-Marc

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Electric heat and only electric heat is what you want to generate warm by. ... We had a small fiberglass (Boler brand) travel trailer growing up. We always went to campgrounds with electricity, as the dryness of electric heat made for moderately comfortable sleeping for 4.

No, that is just not true.

Electric heaters do not dry the air. Moisture in the air does not disapear without a trace when you plug in an electric heater. It's just basic physics.
 

racecougar

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Missouri
Electric heat and only electric heat is what you want to generate warm by. Though it has not been a problem for me I've been warned mightily by member here about using open air, unvented (ie, portable not chimney's) combustion heaters. We had a small fiberglass (Boler brand) travel trailer growing up. We always went to campgrounds with electricity, as the dryness of electric heat made for moderately comfortable sleeping for 4.
Could be worse... you could have frost rather than droplets. ;)
Heat pump, wood, vented NG or Propane...these will also produce good heat without adding additional H2O to the air. Resistance heaters are not the most cost effective solution in most, if not nearly all, cases.
 

jar944

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Northern VA
No, that is just not true.

Electric heaters do not dry the air. Moisture in the air does not disapear without a trace when you plug in an electric heater. It's just basic physics.

While I agree about electric not being anything special. Heat (temperature) does make [free water condensation] dissappear.. for all intents.
 

Jeepster04

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Joined
Jun 25, 2013
Messages
3,112
While I agree about electric not being anything special. Heat (temperature) does make [free water condensation] dissappear.. for all intents.
Can you explain? Are you talking about warming up the objects above the dew point? When I google 'free water condensation', it appears that term does not exist.
 

jar944

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Can you explain? Are you talking about warming up the objects above the dew point? When I google 'free water condensation', it appears that term does not exist.

Yes. Get everything inside warm enough and any condensation problem disappears.
 

chinboys

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Joined
Jun 20, 2011
Messages
434
You have moisture-laden air leaking into the garage from the main house, or leftover moisture-laden air trapped from the house or from prior air infiltration from a garage opening (door, garage door, window(s), vents) that gives up its moisture to things (walls, metal, plastic, etc) that are at the air temperature or colder... dewpoint of materials relative to air and air dewpoint ... hence condensation.

Improve air circulation and venting.
Make sure your main house's humidity and heat are not adding to your garage's unconditioned space.
Keep a window and or a door open but remind yourself that animals might want to come in for shelter.

My unconditioned garage is attached and sealed from the main house.
I have aux heaters to keep auto, motorcycle, and extra tool batteries in an insulated case.
My garage also is very air leaky (air exchanges many times an hour)
 

nadogail

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Joined
Jan 23, 2009
Messages
32,278
Location
Coronado, CA
Hi all

I’m in desperate need of some help, and am suffering full blown anxiety attack over my garage, which has just broken out quite suddenly in pretty extreme condensation for the first time.

So I noticed this morning that everything metal or plastic in my garage was covered in condensation/beads of water and soaking. On top of this the entire floor which has some hard pvc interlocking tiles fitted over the concrete is soaked all over and it just seems to keep building up more and more on the floor tiles in particular. Upon first discovering it I I tried to wipe down what I could as well as the floors. but it doesn’t seems to have helped, the floor tiles for example returned to being wet again within a couple of hours.

I’ve read people suggesting a dehumidifier, so I’ve put the one we have from our house out in the garage tonight and so far had it running for almost 6 hours. The garage floor is still soaked and the air humidity doesn’t seem to have dropped at all (started at 90, still resting at 90) air temperature is about 9 degrees in there as of early hours of the morning/right now. I did tape over the vents and push some plastic wrap under the garage door to try to reduce pulling in outside air where possible though may not have done a great job, and certainly haven’t sealed around the entire door etc, but since 6 hours later and I’m seemingly no better off, can still see new condensation formed on tiles I’d wiped already since humidifier was running, and the humidity is still measuring the same.



As an aside as this hadn’t happened before I wondered - why now? The floor tiles were laid about 14 months ago so have seen a full winter before and so what has changed that could have triggered it? A few things that I wondered if could be relevant:

1. we just had pretty cold weather for a week and snow which stayed present for a few days, followed by sudden rain and increase temps overnight and we currently have generally high humidity to boot (90% outside right now)

2. For the past 2 days I was doing some jobs on the car outside and had the garage door open for several hours on each day (this during rain today, and very cold day yesterday with snow still on ground outside) - not sure if this could have been a catalyst??

3. We had mushroom vents installed a few months ago into the ceilings as the timber roof by the house builder as the timber roof had a little damp/some mold spores that were previously treated after a little damp 2 years ago was noticed on the ceiling shortly after moving in (this seemed to sort it self out and was generally fairly dry for past 18 months, but as other houses on the development had experienced issues the house builder offered to install additional mushroom ventilation in ceiling on all the garages so when offered we accepted on their recommendation.



So a bit of details on the garage that may also be useful . My house is a new build 2.5 years old, and the garage is on the side where it shares about 80% of one side of its wall with the house. It is of single brick construction and shares just the one wall with the house. Up and over door to front and personel door to rear. Two vents to front above door and two to rear at equivalent height. 6 mushroom vents in ceiling. No windows. Wooden flat roof with some kind of plasticy looking coating on the roof (not sure what this really is). It’s a very basic garage. Inside the garage floor sits about 5 inches lower than The ground level of the garden patio and house and there are some areas of the garage internal brickwork that feel a little damp below the dpc. Their is a guttering down pipe that and garage guttering down pipe that run the ground near the rear corner to a soak away that may be contributing to a bit of damp in one area of the brickwork below dpc - but honestly I don’t know.

I’m at a total loss of what’s happened here and why now all of sudden and what to do. I had hoped putting the dehumidifier in there tonight I’d see the levels dropping but they haven’t dropped even by 1% and the condensation is still continuing to build allover the floor tiles. I lifted some other floor tiles and they seem dry underneath.

Appreciate any help and advise, I’m getting seriously stressed out by it, I thought chucking in the dehumidifier would start to bring the humidity down slowly after a few hours, but nothing so far…
In reflection, before I can offer any constructive comments I want to know your approximate location and the tempereture scale you are using
 
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