Sweating metal building
- Thread starter hilld
- Start date
MrJimi
Elite Member, Rest in Peace
Your moister is coming from your unsealed floor?
I live in Florida which I think is the moisture capital of the world?
I don't have a moisture problem here and you should not either if your floor is sealed against moisture
Jim /forums/images/graemlins/smile.gif
I live in Florida which I think is the moisture capital of the world?
I don't have a moisture problem here and you should not either if your floor is sealed against moisture
Jim /forums/images/graemlins/smile.gif
Highbeam
Super Member
If the moisture has gotten behind the insulation then it would seem logical that you haven't sealed the warm side of the insulation with an appropriate vapor barrier well enough. This is why they use plastic vapor barriers inside walls in homes. Now that all that moisture is back there it will take a trick to get it out before resealing.
Cord
Veteran Member
Exactly. He's in a heating climate and has the vapor barrier on the cold side.
EddieWalker
Epic Contributor
Derek,
I don't believe buildings sweat, and I don't think yours is either. And I especially don't think a vapor barier down under you pad will have any effect on moisture in your shop.
The vapor barrier under concrete is to stop moisture from the ground soaking into your concrete when it's poured. For maximum strength, you want you mix as dry as possible. Just a little extra water can lowere the strenght of your pad by 20 percent. Same mix, just more water. In dryier climates and down here in the south, it's extremely rare to use a vapor barrier. We don't need it.
We also have extreme humidity. Moisture comes into a building from the humidity in the air, or from rain. Not from the ground up through the concrete!!!!!!!!!
There are two reasons for moisture in your building.
First, there is a change in temps inside your building from the oustside and you have a condensation issue. If there is a huge tempature difference, than the moisute in the air will turn to water where it gets cold. Imagine a cold drink with ice in it out on the porch on a hot day. Same thing.
Are you heating your shop?
Are you parking a very hot vehicle in there and rapidly changing the air temps?
Are you welding or do other projects that generate allot of heat?
I serioustly doubt this is the cause because of your insulation and vapor barrier.
The other reason is there's a leak.
How well was your roof installed. Did they use top quality screws with good rubber gaskets? This is where most metal roofs fail. Cheap screws usually only last a few years than you get leaks. Moisure inside the insulation makes me think you got a leaky roof.
Is there allot of morning dew in the morning that's on your roof? That's all the moisture you need. It will leak through bad screws and soak your insulation.
The other way would be through the seams on a metal roof. What pitch is your roof? If it's fairly flat, like a 2:12 or a 1:12, than you HAVE to seal the overlaps of the roof.
From what you've said, this is what I think is the problem.
Do a test. remove the insulation in an area to the bare roof. first thing in the morning, get on a ladder and get really close to the roof. Your face should be inches away from it. Can you see water comeing through at the seams or where the screws fasten it to the purlins?
Good luck,
Eddie
I don't believe buildings sweat, and I don't think yours is either. And I especially don't think a vapor barier down under you pad will have any effect on moisture in your shop.
The vapor barrier under concrete is to stop moisture from the ground soaking into your concrete when it's poured. For maximum strength, you want you mix as dry as possible. Just a little extra water can lowere the strenght of your pad by 20 percent. Same mix, just more water. In dryier climates and down here in the south, it's extremely rare to use a vapor barrier. We don't need it.
We also have extreme humidity. Moisture comes into a building from the humidity in the air, or from rain. Not from the ground up through the concrete!!!!!!!!!
There are two reasons for moisture in your building.
First, there is a change in temps inside your building from the oustside and you have a condensation issue. If there is a huge tempature difference, than the moisute in the air will turn to water where it gets cold. Imagine a cold drink with ice in it out on the porch on a hot day. Same thing.
Are you heating your shop?
Are you parking a very hot vehicle in there and rapidly changing the air temps?
Are you welding or do other projects that generate allot of heat?
I serioustly doubt this is the cause because of your insulation and vapor barrier.
The other reason is there's a leak.
How well was your roof installed. Did they use top quality screws with good rubber gaskets? This is where most metal roofs fail. Cheap screws usually only last a few years than you get leaks. Moisure inside the insulation makes me think you got a leaky roof.
Is there allot of morning dew in the morning that's on your roof? That's all the moisture you need. It will leak through bad screws and soak your insulation.
The other way would be through the seams on a metal roof. What pitch is your roof? If it's fairly flat, like a 2:12 or a 1:12, than you HAVE to seal the overlaps of the roof.
From what you've said, this is what I think is the problem.
Do a test. remove the insulation in an area to the bare roof. first thing in the morning, get on a ladder and get really close to the roof. Your face should be inches away from it. Can you see water comeing through at the seams or where the screws fasten it to the purlins?
Good luck,
Eddie
This forum consists of a diverse area of the U.S. I have to agree with Eddie in that buildings do not sweat as such. It is a normal event with dissimilar materials. I don't think a vapor barrier beneath the concrete nor a vapor barrier on the walls over the insulation will help. When you have frost in the ground and on a warm spring day, obviously we have the cold beer can effect on a humid summer day without air conditioning. The spring warm airs are loaded with moisture and they hit the concrete slab or the insulated walls against a metal wall, condensation is bound to occur. This is especially the factor on north walls or walls with less exposure to the sun. HVAC or air exchangers might be the answer. As long as a constant flow of new air is introduced to the building, the moisture will pass more quickly. This is the beauty of infloor hydronic heat. I haven't a answer as to keeping the insulation dry next year. Wet isn't good against the metal. I'm not going to get into as to why we can't have vapor barriers on both sides of the insulation in a metal building. I will follow any of the recommended thought as to vapor barriers, insulation and concrete with hydronic heat as the engineers must know more than myself. I'm always open to thought and ideas from this group. Thanks - Clyde
Eddie,
thanks for the input.
Here are some of the details you asked about.
The roof is a 5:12 pitch and does not leak (We - the builder and myself during a torrential downpour), I have condensation on days where the humidity is high (lately that has been the last 4 months), even if it doesn't rain. If there is no rain and sunshine, the problem seems to go away. While I have not been on the roof, the siding screws have all the neoprene washers intact. On this particular roof, the screws are on the high spots, not the valleys of the metal, gutters have been installed to prevent water running down the sides.
From all the reading I have done is the lack of ventilation (building is tight), and my original question was if a forced ventilation system such as an ERV (Energy recovery ventilator) or HRV (heat recovery ventilator) would solve any of those issues. I do have a heat pump for the barn (studio), but haven't installed it yet, right now I am just heating it with electric space heaters and moving air around the inside with some box fans.
I have painted some of the sheetrock in the building and it took almost 2 days for everything to dry, with inside temp around 62F. There are a couple of spots on the concrete floor near the exterior perimeter, where the paint still hasn't dried.
I am hoping for some sunny days, but the forecast doesn't look good. I will try to get the heat pump (at least the electric auxillary heat) going this weekend to see if that helps in drying the building out. I have tried heating it with propane, but propane bullet heaters introduce a lot of moisture during the combustion process and makes the problem even worse.
The quest for the perfect solutions continue
Derek
thanks for the input.
Here are some of the details you asked about.
The roof is a 5:12 pitch and does not leak (We - the builder and myself during a torrential downpour), I have condensation on days where the humidity is high (lately that has been the last 4 months), even if it doesn't rain. If there is no rain and sunshine, the problem seems to go away. While I have not been on the roof, the siding screws have all the neoprene washers intact. On this particular roof, the screws are on the high spots, not the valleys of the metal, gutters have been installed to prevent water running down the sides.
From all the reading I have done is the lack of ventilation (building is tight), and my original question was if a forced ventilation system such as an ERV (Energy recovery ventilator) or HRV (heat recovery ventilator) would solve any of those issues. I do have a heat pump for the barn (studio), but haven't installed it yet, right now I am just heating it with electric space heaters and moving air around the inside with some box fans.
I have painted some of the sheetrock in the building and it took almost 2 days for everything to dry, with inside temp around 62F. There are a couple of spots on the concrete floor near the exterior perimeter, where the paint still hasn't dried.
I am hoping for some sunny days, but the forecast doesn't look good. I will try to get the heat pump (at least the electric auxillary heat) going this weekend to see if that helps in drying the building out. I have tried heating it with propane, but propane bullet heaters introduce a lot of moisture during the combustion process and makes the problem even worse.
The quest for the perfect solutions continue
Derek
EddieWalker
Epic Contributor
I understand your assurance that the roof doesn't leak, and you could very well be correct. What really caught my attention was your statement "On this particular roof, the screws are on the high spots, not the valleys of the metal."
How did you get the screws from the high spots to the pulins?? I've never seen this, and in my experience, this is a huge mistake in all the forms of metal roofing I've seen. I'm not a roofer, but I've done a few, so there's plenty I don't know.
It just seems to me that it would be very dificult to get the metal tight with a space in between the metal and the purlin. The screws would bow out the high spots and stretch out the overall shape of the metal.
The other thing to look at is how tight the screws are. They have to be snug with just a small amount of bulging. NOT TIGHT!!!! If they are overtightened, the gaskets will break or open up. If they are too tight, they will leak.
Can you take pictures?
The next thing I'm wondering is if there's any venting of any kind? It sounds like you have no air space above your insulation and the roof. This might also be the cause of your condensation. Is there any way to circulate air in this area?
Again, pictures would really help.
What has your builder said? If he's been building in the area, he should have enountered this before.
Eddie
How did you get the screws from the high spots to the pulins?? I've never seen this, and in my experience, this is a huge mistake in all the forms of metal roofing I've seen. I'm not a roofer, but I've done a few, so there's plenty I don't know.
It just seems to me that it would be very dificult to get the metal tight with a space in between the metal and the purlin. The screws would bow out the high spots and stretch out the overall shape of the metal.
The other thing to look at is how tight the screws are. They have to be snug with just a small amount of bulging. NOT TIGHT!!!! If they are overtightened, the gaskets will break or open up. If they are too tight, they will leak.
Can you take pictures?
The next thing I'm wondering is if there's any venting of any kind? It sounds like you have no air space above your insulation and the roof. This might also be the cause of your condensation. Is there any way to circulate air in this area?
Again, pictures would really help.
What has your builder said? If he's been building in the area, he should have enountered this before.
Eddie
Eddie,
I will try and take some pics tomorrow, unfotunately the roof is pretty high up.
The builder specializes in Pole barns (the wood kind), rather than all metal buildings. He does a few of these a year (that is what he told me). There is no ventilation to the outside of any kind, that is why I was wondering about the ERV or HRV's (see previous post) to bring in fresh air without much heat and or moisture gain.
I did manage to get the heat pump (air handler with aux heat) running around 11pm and will let it run overnight to see if a little heat and some serious air movement helps the problem. Previously when I used propane heat, it caused lots more problems since the combustion of propane creates water vapor and while the building gets warm, it is like a Florida summer day. I want Arizona heat. /forums/images/graemlins/grin.gif
I will try to the outdoor unit installed this weekend, barring any other honey do projects and call a heating contractor to evacuate and charge the system so I can get more efficient heat.
Hopefully with all of our combined heads, I will find a solution.
Derek
I will try and take some pics tomorrow, unfotunately the roof is pretty high up.
The builder specializes in Pole barns (the wood kind), rather than all metal buildings. He does a few of these a year (that is what he told me). There is no ventilation to the outside of any kind, that is why I was wondering about the ERV or HRV's (see previous post) to bring in fresh air without much heat and or moisture gain.
I did manage to get the heat pump (air handler with aux heat) running around 11pm and will let it run overnight to see if a little heat and some serious air movement helps the problem. Previously when I used propane heat, it caused lots more problems since the combustion of propane creates water vapor and while the building gets warm, it is like a Florida summer day. I want Arizona heat. /forums/images/graemlins/grin.gif
I will try to the outdoor unit installed this weekend, barring any other honey do projects and call a heating contractor to evacuate and charge the system so I can get more efficient heat.
Hopefully with all of our combined heads, I will find a solution.
Derek