Best way to insulate attic under a metal roof

Andrew OConnor
My home was originally built between 1970 and 72 here in the Atlanta Metro area in north Georgia. This climate is predominantly hot and very humid from late June until about early October and the winters are comparatively mild versus the Northeast where I came from. We do get ice and occasionally snow - ice being a bigger problem - every couple years. The owners of the house which I bought in 2006 and live in still today, replaced the original roof with a brand new metal roof. It looks standard industrial style vertical panels in long sheets. I suspect the trusses were also installed new back when they replaced the roof however the ceiling of the house under the attic is probably original. It looks original simply because it's a standard popcorn ceiling which hasn't been used since then. I added blown in standard insulation to the attic to an R25-27 depth on top of what was already there. There are areas where I am noticing discoloration of the ceiling on the inside, and I'm absolutely terrified of mold. There are no leaks in the roof as I hired a local contractor about 3 years ago to do a complete and comprehensive review of all of the pipes, screws etc and replace as necessary. There is no insulation applied directly to the underside of the metal sheets which are screwed into plywood which is in turn attached to the trusses and both attics ( which form non connecting l-shape are well vented from both sides. My question: is there anything that I should do to insulate the roof and or the ceiling from the massive temperature difference when I run my AC in the summer between the air in the attic in the air in my home that could potential mix, causing moisture condensation and maybe mold? What's the best way to approach insulating this kind of attic/roof and what are the industry best practices that I should check for and or add if missing?
Todd Miller
Isaiah Industries, Inc.
What you have, unless I am missing something, seems like a pretty standard application. Do you have proper ventilation in the attic? Certainly, if you add insulation, I'd add it on top of the ceilings. But, above that, i'd suggest attic ventilation consisting of both intake vents at the bottom and some sort of vent at the pep of the roof, either ridge vent or something off the ridge. Based upon your post, I wonder if you have intake vents but no exhaust vents.
Andrew OConnor
I will take some photos and post.. I do have intake vents at the base of the attic and larger ones at the top of the triangle areas at both ends... They are clear and as I say as of 3 years ago I am certain I have no roof leaks as I had the largest contractor in Atlanta AAA Metal Roofs come out and do maintenance for me in causing rebooting all pipes, replacing hundreds of screws and adding the vent line pads at the top of the roof's v apexes where the slopes intersect...
Eric Novotny
An informed customer is the Best Customer!
What is the relative humidity like in the home?

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