Condensation on Metal Garage Roof
Discussion
I have a two bay garage with a sheet metal roof. Was never a problem until I sealed the floor with paint. Now a few weeks later I am getting drips of condensation from the roof. Maybe I never noticed before because the floor absorbed it.
Anyway lots of anti-condensation stuff online to paint the ceiling with but wanted to ask the masses whether anyone had done this and sorted everything, or whether its just expensive snake oil, and I should look to pay even more money for an insulated roof?
Anyway lots of anti-condensation stuff online to paint the ceiling with but wanted to ask the masses whether anyone had done this and sorted everything, or whether its just expensive snake oil, and I should look to pay even more money for an insulated roof?
Painted it three weeks ago. Floor is all died out so I don't think that's the problem.
As for warm air. The garage is quite drafty but sun facing. The roof slopes backward and is almost edge on this time of year so stays cold. I think the sun heats up the garage doors/front and the air inside hits the ice cold roof and condensation forms.
You can see the entire roof inside has droplets of water on it.
As for warm air. The garage is quite drafty but sun facing. The roof slopes backward and is almost edge on this time of year so stays cold. I think the sun heats up the garage doors/front and the air inside hits the ice cold roof and condensation forms.
You can see the entire roof inside has droplets of water on it.
julian64 said:
I have a two bay garage with a sheet metal roof. Was never a problem until I sealed the floor with paint. Now a few weeks later I am getting drips of condensation from the roof. Maybe I never noticed before because the floor absorbed it.
Anyway lots of anti-condensation stuff online to paint the ceiling with but wanted to ask the masses whether anyone had done this and sorted everything, or whether its just expensive snake oil, and I should look to pay even more money for an insulated roof?
Are you sure painting the floors not a coincidence? We are right In the zone for condensation right now. I have a pre fab concrete garage. Concrete walls, concrete unsealed floor , steel roof. It used to flood like nothing else, I could literally see it running down and dripping everywhere. I sorted it by fixing 10mm sheets of polystyrene the roof, it basically keeps the garage space at a constant temp. Anyway lots of anti-condensation stuff online to paint the ceiling with but wanted to ask the masses whether anyone had done this and sorted everything, or whether its just expensive snake oil, and I should look to pay even more money for an insulated roof?
I used to rent a pre-fab concrete garage which had similar issues (i.e. when the outside air temperature dropped the thin roof became cooler which causes the moisture to condense out of the relatively warmer garage air). Because it was rented I didn't want to put to much effort into solving it but managed it by suspending a tarpaulin under it at an angle which allowed the water to drain down to a catch at the back of the garage.
Insulating the roof as mentioned above seems a like a step up from this however if you can find the time.
Insulating the roof as mentioned above seems a like a step up from this however if you can find the time.
I was either thinking of painting the roof which I think will make a massive mess on the new floor, or replacing the roof panels with different insulated ones.
Trouble is that anti condensation paint sounds like snake oil because it talks about absorbing moisture when I think what you really need is an insulating layer. The anti-condensation roof panels just look pre painted with the same stuff although probably better than I could do it hanging upside down.
I think I'm onto a loser as the two cars parked in there for the last two weeks are now soaked inside (open top) and neither of them will start
. Damp, contact points usual nightmare.
Trouble is that anti condensation paint sounds like snake oil because it talks about absorbing moisture when I think what you really need is an insulating layer. The anti-condensation roof panels just look pre painted with the same stuff although probably better than I could do it hanging upside down.
I think I'm onto a loser as the two cars parked in there for the last two weeks are now soaked inside (open top) and neither of them will start
. Damp, contact points usual nightmare.I have a large metal shed and got really bad condensation the first couple of days, so I bought some foam insulation sheet from B&Q and glued it on to the inside of the roof with "Sticks Like Sh*t" and never had a single problem since.
I think it was this sort of polystyrene stuff, although the stuff I got was thinner, perhaps 1/2 to 1 inch thick:
https://www.diy.com/departments/polystyrene-insula...
I think it was this sort of polystyrene stuff, although the stuff I got was thinner, perhaps 1/2 to 1 inch thick:
https://www.diy.com/departments/polystyrene-insula...
Edited by anonymous-user on Wednesday 4th December 18:32
julian64 said:
I was either thinking of painting the roof which I think will make a massive mess on the new floor, or replacing the roof panels with different insulated ones.
Trouble is that anti condensation paint sounds like snake oil because it talks about absorbing moisture when I think what you really need is an insulating layer. The anti-condensation roof panels just look pre painted with the same stuff although probably better than I could do it hanging upside down.
I think I'm onto a loser as the two cars parked in there for the last two weeks are now soaked inside (open top) and neither of them will start. Damp, contact points usual nightmare.
Can you run a dehumidifier until you get it sorted?Trouble is that anti condensation paint sounds like snake oil because it talks about absorbing moisture when I think what you really need is an insulating layer. The anti-condensation roof panels just look pre painted with the same stuff although probably better than I could do it hanging upside down.
I think I'm onto a loser as the two cars parked in there for the last two weeks are now soaked inside (open top) and neither of them will start
. Damp, contact points usual nightmare.You've got water in the garage I suspect. Check that the roof panels aren't leaking through joints etc.
Ignore the warm air hitting cold roof b
ks - where's the warm air coming from? Unless the garage is heated I don't think that's the cause. If it's cold outside, it'll be cold inside. If you've got no airflow in the garage then the air wont be wet. If there's airflow, then the air will be the same as outside. Hence, the wet air in the garage is due to a water source in the garage. Plug the leak and you'll find it stays dry.
Ignore the warm air hitting cold roof b
ks - where's the warm air coming from? Unless the garage is heated I don't think that's the cause. If it's cold outside, it'll be cold inside. If you've got no airflow in the garage then the air wont be wet. If there's airflow, then the air will be the same as outside. Hence, the wet air in the garage is due to a water source in the garage. Plug the leak and you'll find it stays dry.fiju said:
Ignore the warm air hitting cold roof bks...If there's airflow, then the air will be the same as outside
Whole post is nonsense, I'm afraid.ks...If there's airflow, then the air will be the same as outsideBut to focus on one specific point, airflow over a pitched roof changes its pressure. Changing the pressure of air changes its temperature, which in turn changes the temperature of the roof surface it's flowing over.
A big, flat panel of metal cooled to below ambient air temperature is just about the finest condensing surface known to man...
fiju said:
You've got water in the garage I suspect. Check that the roof panels aren't leaking through joints etc.
Ignore the warm air hitting cold roof bks - where's the warm air coming from? Unless the garage is heated I don't think that's the cause. If it's cold outside, it'll be cold inside. If you've got no airflow in the garage then the air wont be wet. If there's airflow, then the air will be the same as outside. Hence, the wet air in the garage is due to a water source in the garage. Plug the leak and you'll find it stays dry.
The large amount of air in the garage will have a thermal mass which is heated during the day by the sun so it's warm relative to the air outside the garage which generally cools as the day ends. The volume of air can be considered fixed given any airflow will have a negligeable effect on the time taken to form condensation.Ignore the warm air hitting cold roof b
ks - where's the warm air coming from? Unless the garage is heated I don't think that's the cause. If it's cold outside, it'll be cold inside. If you've got no airflow in the garage then the air wont be wet. If there's airflow, then the air will be the same as outside. Hence, the wet air in the garage is due to a water source in the garage. Plug the leak and you'll find it stays dry.It's easy to see whether this is causing the issue as the condensation is likely to be much worse in the evening time. Whereas with your theory the water will only appear after it's rained but I'm pretty sure the OP would have been clever enough to have joined those two dots.
I'm not disagreeing that water will condense on the underside of a roof, however, attributing that solely to the cause and effect is something I can disagree with. You need quite a change in humidity for it be considered. The stagnant air alone won't be the cause, it will be the same air as the air outside, unless it's airtight. If it's cold outside, it will be cold inside. I imagine you'd also need a rapid change in temperature, versus the change in humidity for it to occur. So if there's airflow, unless it got cold quite quickly, you won't get condensation. Does that make sense?
I'm going to say that there's a leak, or water has been introduced into the garage in some way. Something may be storing water (wood, carpet, insulation etc. Do you have wooden roof joists?) and as it evaporates through the day, causes the rise in humidity, which condenses on the roof. Concrete will soak up the drips, but you are now able to see it as it has nowhere to go because you painted the floor.
A quick and easy solution to verify this idea would be to paint the outside of the roof with roof paint. Even easier would be to lay a tarp to cover the whole roof.
I'm going to say that there's a leak, or water has been introduced into the garage in some way. Something may be storing water (wood, carpet, insulation etc. Do you have wooden roof joists?) and as it evaporates through the day, causes the rise in humidity, which condenses on the roof. Concrete will soak up the drips, but you are now able to see it as it has nowhere to go because you painted the floor.
A quick and easy solution to verify this idea would be to paint the outside of the roof with roof paint. Even easier would be to lay a tarp to cover the whole roof.
fiju said:
I'm not disagreeing that water will condense on the underside of a roof, however, attributing that solely to the cause and effect is something I can disagree with. You need quite a change in humidity for it be considered. The stagnant air alone won't be the cause, it will be the same air as the air outside, unless it's airtight. If it's cold outside, it will be cold inside. I imagine you'd also need a rapid change in temperature, versus the change in humidity for it to occur. So if there's airflow, unless it got cold quite quickly, you won't get condensation. Does that make sense?
I'm going to say that there's a leak, or water has been introduced into the garage in some way. Something may be storing water (wood, carpet, insulation etc. Do you have wooden roof joists?) and as it evaporates through the day, causes the rise in humidity, which condenses on the roof. Concrete will soak up the drips, but you are now able to see it as it has nowhere to go because you painted the floor.
A quick and easy solution to verify this idea would be to paint the outside of the roof with roof paint. Even easier would be to lay a tarp to cover the whole roof.
You think the air in the garage will cool at the exact same rate as the air outside? Of course it won't as the main thing cooling the garage air is the roof itself. Hence the condensation appears due to the air suddenly losing it's capacity to retain as much moisture when it rapidly cools as it comes into contact with the colder roof surface.I'm going to say that there's a leak, or water has been introduced into the garage in some way. Something may be storing water (wood, carpet, insulation etc. Do you have wooden roof joists?) and as it evaporates through the day, causes the rise in humidity, which condenses on the roof. Concrete will soak up the drips, but you are now able to see it as it has nowhere to go because you painted the floor.
A quick and easy solution to verify this idea would be to paint the outside of the roof with roof paint. Even easier would be to lay a tarp to cover the whole roof.
Wacky Racer said:
I had a large (unheated) ...... garage in my old house with a metal sheet roof, the condensation was awful, thousands of drips everywhere, it was fine in the summer.
Same. I think the floor is just showing the drips, and or, the season has changed.What are the walls made out of? Mine where also steel, didnt seal to the floor, so i used to get surface run off water into the garage as well.
During the day it all get nice a warm, then at night the temperature drops off and it condenses onto the roof and to a less extent walls.
Easiest option might well be replacing the room with insulated sheets, most of these have flocking on the underside also.
Alternatively a cheaper option would likely be to increase ventilation a load so that the air ic changed as the duw point falls.
I also kept a stack load of my stuff in clear plastic storage boxes with lids.
Daniel
had this in a rented garage , i fixed up a wooden batton frame with cable ties etc a few inches below the roof then fixed a sheet of plastic over the frame , this stopped the warm /cold air meeting and caught the few drips that remained
cost next to nothing and no alterations to the structure of the garage
cost next to nothing and no alterations to the structure of the garage
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