TOPIC: I Have An Existing Metal Roof and Have A Question
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3 years ago we built our home. We paid a contractor to build all the foundation, framework, roofing and siding and we did everything else. The contractor put a polyethylene sheet directly under the metal roof on top of the support beams. They then put the insulation up against the roof and then dry wall. So it’s interior of house and then drywall, insulation, polyethylene sheeting, and then metal roofing all “stacked” and then exterior of house. We are having problems with condensation dripping down on our front porch (just metal roof- no polyethylene or insulation) and it got me wondering if condensation is dripping inside the insulation also. Does this sound like it is installed correctly? Is there any simple way to check if we are having condensation problems inside the house that could cause major issues?
It is not at all unusual for dew to form on the outside of the metal roof, if that is what you're referring to. Dew forms on the underside if warm moist air from inside the home reaches the underside of the roof. You do not have ventilation so you're dependent upon the insulation to help avoid this. I wish you had polyethylene vapor barrier behind the drywall. I'd keep a close eye on your ceilings for any signs of water damage. You can also try to keep moisture levels low in the home and keep any ceiling fans or HVAC fans running continuous especially during the cooler seasons.
Thank you so much for such a quick reply and for answering my questions!
Yes, from other posts I got the impression that they placed the polyethylene sheeting in the wrong place (above insulation rather than below insulation). The dew I was referring to on the porch is on the underside of the porch and drips down onto the porch every morning. I will keep an eye on the ceilings. There is a very small portion of the house that has attic space that I plan on checking tomorrow morning to see if it’s dripping.
Thank you so much for answering all of my questions and for your quick reply!
Yes, from reading other forums I got the impression that the polyethylene sheeting was installed improperly (above insulation rather than below insulation). I will keep an eye on the ceilings. We do have a very small area of the house with an attic. I went and checked in there and sure enough there is small amounts of black mold forming on the beams. Is there much we can do about this??
I am sorry to hear this. You might have some success by painting your ceilings with oil base paint that moisture won't make its way through. Keep an eye on overall moisture levels inside the home and keep fans running. You could perhaps add a vapor barrier over the existing ceiling and then another layer of drywall but that would be a real mess.
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