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I am having a metal roof installed on my house in Los Angeles. The roofer tore off existing shingles down to the plywood, then installed a layer of new plywood, followed by a 1.5" layer of polyiso rigid insulation (because of my open beam ceilings), then another layer of plywood and then a layer of underlayment. He started installing Berridge Cee-Lock 1-1/2" high standing seam metal roofing over the underlayment yesterday. Looks beautiful. Last night it started raining when only about 1/4 of the roof was covered with metal. This morning when they arrived to continue the job the underlayment and stored metal panels were wet from the rain last night. It is raining and expected to rain off and on throughout the week, so I do not expect there to be much chance for things to thoroughly dry out over the next few days but they want to continue to work as much as possible this week. Is there any problem with the roofer continuing to install metal panels over wet underlayment? Should I have them wait until next week when the rain is over? My concern is that moisture will be trapped causing potential problems (mold, rust etc.) or decreasing the life of the roof. Do you believe it is ok for my roofer to proceed with the installation in the rain and, if so, why? Is there ventilation that will permit that moisture to be eliminated before it could become a problem? Thanks very much for your help and explanation.
Jon, this is done on a regular basis and, in 35 years, I have yet to see anything bad come of it. Thanks for thinking metallically, by the way!
Thanks Todd. Glad to hear that. I appreciate your prompt response and assistance.
My contractor has covered an asphalt shingle roof with 5/8” plywood over which he is installing 26ga standing seam. Looks great! I’m located in ‘rainland’ and the contractor was only able to complete maybe 1/5 of the metal installation. I insisted he cover the exposed plywood with waterproofing which he did but used a cheap product which did little good. The plywood is now wet and will get wetter. He said he will pull the protective material off (when back from vaca) and let the roof dry out and then put an impervious sheet of black plastic on it for the winter. He plans to work on installing the metal during our occasional dry spells. My concern is that the plywood will not really dry in the cold weather and we will have trapped moisture if he ends up installing metal over semi-wet ply.
I have read some of the others similar concerns above but would appreciate your response in any case. This is such an expensive endeavor for me and I am alone and slightly concerned I’m being taken advantage of.
Thank you very much for your reply!
In your exact case, I would recommend that he install a quality breathable underlayment on the roof after he removes the current material. A breathable will allow the decking to dry out but yet still protect it from further moisture. The product I am most familiar with is Cromar VENT3 but there are others as well.
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