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Alex Turchi
12/9/2011
I have an old workshop with a tin roof that I converted into a conditioned office. It has a vaulted ceiling that I had spray foamed (directly to the roof) with open cell insulation prior to drywalling. Now that it is winter time I notice condensation on the outside of the roof each morning. Do I need to be concerned that there will be condensation on the inside of the roof if not now, then in the summertime when the temperatures reverse? I'm concerned that if there is condensation it will cause long term damage to the rafters/structure, not to mention mold etc.
Todd Miller
Isaiah Industries, Inc.
12/9/2011
It sounds like you have done the right things. Condensation on the outside does not normally correlate with condensation on the inside.
Eric Novotny
An informed customer is the Best Customer!
12/9/2011
Alex, Condensation to the exterior roof surface is an indication that dew point is being achieved and that the roof surface is cold. In this season (i.e. winter) a cold roof means that the insulation layer is doing its job. Your climate is mild and you do not really need a vapor barrier but you should strive to have an airtight ceiling. Air leaks will care exponentially more moisture to the surface and can lead to condensation on the underside of the metal if you allow it to. Air tight ceiling is a must. Spray foam is great and open cell is an air barrier, however, it is very vapor permeable. Not so much of an issue in NC and not a big issue unless you take a bunch of showers in that area or are generating a bunch of humidity.
Alex Turchi
12/14/2011
Thank you for the information. This definitely makes me feel better about the long-term viability of my office. I am thinking about adding a bathroom in the future. Are there any considerations I should take into account? Sounds like I should have a good exhaust fan for the moisture. If I go with spray foam again should I add a vapor barrier to the ceiling? Thanks again, Alex
Eric Novotny
An informed customer is the Best Customer!
12/15/2011
Good exhaust fan, make sure the ceiling is air tight. If you spray foam the roof, open cell is not a vapor barrier and will require a supplemental one, if at all, over the bathroom. Closed cell is a vapor barrier at over 2-3" and does not require anything else.
Melissa Oberlander
12/26/2011
I have a new steel building on my property and it seems to have condensation dripping off of the inside insulation. I had the company put in a ridge vent and copola. I put vaper barrier under the cement floor. Is this normal? How can I prevent this as I want to store hay inside the building. Thankyou, Melissa
Todd Miller
Isaiah Industries, Inc.
12/26/2011
Hi Melissa. Thanks for the question. How is air being fed to the ridge vent? Where is that air coming from? Also tell me about the insulation. Does it nclude a vapor barrier on the bottom side? Is the r value adequate?
Guest User
12/27/2011
recently built a Pre-engineered steel building(standing seam roof) to live in while I build a conventional house the roof and wall are insulated with typical pre-engineeered building insulation R13 walls and R19 roof sys with WMP facing. Ice is forming between the insulation and the roof panels I assume this is because of high humity. what are your thoughts
Todd Miller
Isaiah Industries, Inc.
12/27/2011
clifr, is there any sort of vapor barrier to keep moisture from getting through and/or around the insulation?
Guest User
12/27/2011
No just the Cl1510 WMP-50 facing with one 6" tab seams seem to be pretty good with little sign of gaps
Todd Miller
Isaiah Industries, Inc.
12/27/2011
Interesting. Well, someplace it sounds like moisture is getting through or around it. Could you consider a complete poly vapor barrier on the inside?
doug scott
1/6/2012
I have a work shop 6000sf and with a metal roof install on 1x4's across wood rafters. I insulated it with fiber glass insulation and an getting condensation leeking through the paper back now. Is there anything I can do to salvage my insulation to stop condesation? Or is tearing it out and spray form the only way?
Todd Miller
Isaiah Industries, Inc.
1/6/2012
Do you have a vapor barrier beneath the insulation, to keep moisture from getting into it?
Eric Novotny
An informed customer is the Best Customer!
1/8/2012
Doug, The insulation is best suited for the trash in most cases like this at this point. As soon as fiberglass gets wet, it begins to grown mold and mildew in most cases and applying the vapor barrier now will not allow it to dry to the inside, hence trapping the moisture in the fiberglass. I would recommend that it be removed in lieu of new insulation and that you make sure you have a proper, continuous, and un-broken vapor barrier applied between the insulation and the warm side of the space.

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