Stopping Condensation

Hi guys. I have a covered porch, with metal roof attached directly to purlins, which are mounted on 2x6’s. Of course, it condensates, worse in spring in fall, but pretty much all year. I want to close it in, and make it my office, and attach part to my bedroom for a master bath.

What’s going to be the best way to stop condensation? My thinking is the best way is to remove the metal roof, and put a vapor barrier between the purlins and the metal roof, but that is next to impossible.

Next thought is put either put 3" insulation with vapor barrier, leaving a 2 1/2 in air space between insulation and metal roof, or putting 6" insulation, not leaving any air space. I’m not sure how I’d vent the air space anyway, unless the ridges in the metal roof is enough air flow.

Rigid foam between all the purlins, but I think the purlins would still sweat.

Also, the ceiling is pretty low on the back side (6’6). I would like to just condition the whole space, but not sure how to deal with the condensation

Any ideas?

Nice to see you back Mr. Clark! Might want to start at the bottom of this project, what is the foundation? May as well go full Monte and remove the metal roof replace with radiant barrier plywood, add insulation with proper ventilation, and then what ever other bells and whistles you can incorporate! :lol:

Thanks, Dave, I been meaning to give you a ring lately, It’s been just crazy busy for me.

It’s a wood deck, Foundation is timber piers. I’m not going to spend too much $$, I’m going to Reinforce the piers, cover the decking with 1/2" plywood, and insulate. If it were a great house, I’d pour footings and do it all full Monte, but I’m just going to nickel this project, as it’s temporary (4-5 year plan). I have acreage, and I’m going to build a house on it eventually. This is on a doublewide, that I will sell (give) to my son when my house is built. I’m just looking for best way and cheapest way to deal with that metal roof when I close the porch in.

Hey Mike good to see you back. If you intend to hand it down to family, make sure there are not moisture issues! I hope you have been busy and working in better conditions than when last we spoke! :wink:

Oh yeah, it’s been non stop working for quite a few months. One of the reasons I want to turn that deck into an office space–more elbow room!

I would go with closed cell spray foam.

Thanks Jeff, I’ve been doing some research on that as well

Me too, or if that is not an option, mineral wool batt (Roxul) to fill the space, air tight vapor barrier, gypsum sheathing fastened to the bottom of the joists, no ventilation either way.