RETURN TO I Have An Existing Metal Roof and Have A Question
RETURN TO FORUM
If warm moist air reaches a cool surface, it will condense. What's happening is that warm moist air is reaching the cold back side of the home's exterior and condensing. Avoiding condensation requires at least two of the following three things, and preferably all three: Vapor Barrier, Insulation, Ventilation.
Interesting. As I recall, at 90 degrees, if humidity is 65%, condensation will occur. Your photos didn't post for some reason. I am sorry. Would you wish to email them to me at todd@asktoddmiller.com
Most inexpensive is likely a product like this: http://dripstop.net
I do not know what Insulguard refers to. Sorry. You could spray the underside of the roof with closed cell urethane foam.
Sorry, generally, this would not be a DIY product. Something of this will require special equipment and chemicals, not just "spray foam in a can" unfortunately. You'd need to go to an insulation contractor with the right equipment and they will have recommendations.
I do not think that will resolve the issue.
Sheila, for some reason the photos did not post. You can email to me direct if you wish. todd@asktoddmiller.com
Bill,
The ceiling needs an air barrier via drywall or some other sort of seamless air barrier.
https://buildingscience.com/documents/information-sheets/air-barriers-airtight-drywall-approach
Needs to be dried out. You need to condition that space and get it dried out first and be sure there is no moisture behind it.
What are the overnight temperature though and what direction does the roof face? You can have condensation on the outside of of your windshield in the middle of summer in the AM and I suspect that is when the condensation is accumulating in this case (i.e. early AM or overnight lows).
Pull back the insulation, condition and dehumidify the space, treat any mold growth, install insulation (Spray foam works well here if you like), insulate, install air barrier.
Sheila,
How about some pictures?
It must be the flashing problem according to me, can be done easily but for that you must hire a professional and ask them to check and fix the leakage issue.
I have a 14x70 swmh with metal walls and roof that has been gutted and is now going back together. I had some roof seams that were leaking and repaired them with Gaco roof tape followed by three coats of Gaco roof coating on the entire roof. The interior had no insulation so I was able to verify the leaks were cured. However, I recently insulated using Owens-Corning kraft-faced insulation; R13 for the walls, R30 for the ceiling. The ceiling is a combination of vaulted and flat. Where it's vaulted, there is no air gap between the ceiling and insulation but where it's flat there is an air gap. I am now seeing moisture on the insulation facing where the flat and vaulted sections meet. There was no rain when this was discovered; in fact it was dry at 9 in the morning but damp by noon. This is on a very hot and humid day. No A/C was being used so there was certainly no cool air present. Is this a condensation issue and if so how do I alleviate it?
I followed the link you sent -- thank you very much. So I need to install drywall and then seal it at the places they recommend. But can I do that if the insulation is damp? Doesn't it have to be dried out first?
Have you ever seen this happen before? We've been reading a lot trying to find out what's going on and we're getting a lot of conflicting information. We just want to be sure we address the true cause of the issue before we go any further.
Here are some of the photos we took once we found it wet.
Just a reminder, it was dry at 9am and wet by noon. It didn't rain at all today.
We just finished insulation last week and we saw no problems at that time. We even went to the trailer twice during heavy storms to look for leaks well before we put insulation up.
Have you ever seen this happen before? We've been reading a lot trying to find out what's going on and we're getting a lot of conflicting information. We just want to be sure we address the true cause of the issue before we go any further.
Here are some of the photos we took once we found it wet.
Just a reminder, it was dry at 9am and wet by noon. It didn't rain at all today.
We just finished insulation last week and we saw no problems at that time. We even went to the trailer twice during heavy storms to look for leaks well before we put insulation up.
But that's not what's happening. There's no cool surface. In fact, the roof was quite hot when the problem surfaced. The inside air was humid to be sure but it too was very warm. At least 90° F. I don't understand how condensation can cause that big a damp area.
Thanks so much, this helps a lot. We are going to pull down the damp insulation so it can dry out and set up temp and humidity gauges inside and out today so we can see what's actually happening.
I'll forward the pictures to your email.
For a vapor barrier, do we need to add something above the insulation in the non-vaulted parts, i.e., where there's an air gap?
Where the insulation is in the vaulted parts there is no air gap and there doesn't appear to be a moisture problem.
One more question. Since we are having condensation problems in the summer should we install A/C units to help dry the air? I would imagine this will only get worse next winter.
I can't thank you enough for taking the time and sharing your knowledge. You're really bailing us out here.
Low was 70 last night. There is condensation at 10 today but it's not as bad as yesterday noon. Yet.
The long sides of the trailer are the east and west sides. Right now only the west side (where the sun hasn't hit yet) is showing droplets on the inside of the metal roof panels. The east side is dry. As dry as anything is at 77% humidity.
You are correct.
I just pulled some insulation down and it is in fact, condensation. Now how do we go about fixing this the right and way?
Should we take down the insulation where the gap is and install it so the insulation is adjacent to the roof? Like it is on the peaked roof part (no condensation where the insulation meets the roof directly)? Should we do this and install attic fans? Or just attic fans? Or just re-do insulation?
Would you please recommend the next, best course of action for us to fix this problem?
Over night temps are in the low to mid 70's - usually 73-74 degrees, consistently through autumn. Highs are in the high 80's to low 90's, consistently, too. I live in the Jacksonville, Florida, area, so the humidity is 100% in the am, and 50-70% at various times throughout the day. The long side of my trailer runs east and west and is not shaded.
Thanks Eric for your prompt replys and great advice. I can't thank you enough.
Bill
I've pulled back the insulation in the problem areas and I have fans pointed at them to dry them out. There's no AC available at this time so the next step is bringing in a pair of 70 pint dehumidifiers (for 980 sq. ft.). Once we get stuff all dried out we'll tack the insulation back up, with some plastic sheeting on top of it. If it stays dry we'll have the drywall installed and make sure it is sealed to the shell at top and bottom and where the interior walls come in contact with the outside walls.
Thanks so much to both Eric and Todd for the prompt and helpful advice. Can't recommend you guys highly enough.
I have an existing pole building with metal sides and roof. No insulation. In the mornings I have condensation on the bottom side of roof panels. It sometimes drips like rain. The shed is 26x48. I put plastic down and poured concrete on an 18x26 area on one end, the rest of the floor I put down plastic with 2 in. of gravel on top. It helped alot, but I still have the condensation problem. What is the most inexpensive way to resolve this?
It sounds good, but it seems like it would be very difficult to install on an existing roof. Is there any kind of a paint type product that could be sprayed on. A local lumberyard told me of an old product called Insulgaurd that might work. Any thoughts on that?
Thank you; How thick would I have to spray the foam? What retailers can I find it at?
Okay; Thanks for all the advice.
I have one more thought on this to run by you. What do you think about installing aluminum bubble foil between the purlins. Tight to the steal. Just thinking out of the box.
We just built a 12×42 porch onto our house. We put a metal roof on it with sheating and vapor bearer. We woke up to dots of water laying where all of the screws were put in. How do we fix this problem?
Did you receive the pics?
Hi,
I have a 36'x36' barn with 6 12'x12' stalls & a hay loft in the center that is 12'x36' with a metal roof. The metal roof was just atached to the 2x4 on the trusses. When it get cold the condensation starts, with out having to remove the roof and sheeting it is there some thing that I can use or do to the underside of the metal roof? (such as spraying it with foam)
It is common to face such roof issues. And insulation is common problem especially during winters. Not bragging our metal roof repair services include:
Rust removal
Application of a rust-prevention product
Surface cleaning
Seam sealing
Screw tightening
Caulking
So call us and get your roof repaired. For more details.
Metal Roof Repair
I have a dwmh with a metal roof install 5/2014. No problems till hurricane Matthew, 10/16. We had a little tornado and one place began leaking. The Dormer is probably the start point. Now it has spread. I love my metal roof and will probably always. Can this tornado have caused so much damage? Also, some screws are loose. Thank you.
It can be a flashing problem.
I have a question I have a mobile home built in 1982 their a lot of condensation on the inside roof. It’s a curve roof metal then cardboard vapor then installation then plastic. As I am redoing the inside I noticed a lot of water well I did trace it to the condensation. But what’s the problem please help me!!
