Anyone else prefer skipping the house wrap on metal siding?

I've spent the last decade tearing down old tobacco barns and equipment sheds here in the Midwest, and honestly, the ones without wrap usually look the best inside. When you're dealing with an unheated space like a pole barn, the metal "sweats" whenever the temperature swings. If you slap Tyvek or a generic house wrap right behind those 29-gauge panels, that condensation gets trapped in a tight sandwich against your wall girts. I’ve seen 2x4 SPF girts turned to mush in five years because the wrap didn't let the moisture evaporate. Those ribs in the corrugated steel act like a natural rainscreen. As long as you aren't insulating it and cranking the heat, the airflow behind the panels keeps the wood dry enough to prevent rot. The real danger isn't the occasional rain blowing in; it's the constant drip of condensation on a humid morning. If you're worried about the fastener holes, just make sure you're using high-quality screws with EPDM washers—brands like ST Fasteners hold up way better than the cheap bulk stuff you find at the big box stores.

I have to disagree with the idea that skipping the wrap is always safer for the structure. I put up a 40x60 cold storage shop back in 2012 following that 'breathable' logic, and when I went to add a lean-to last summer, I pulled a few panels and found black mold starting on the 2x4 girts. Wind-driven rain pushes right thru the lap joints of those 29-gauge panels, expecially during our heavy spring storms. Instead of traditional Tyvek, I’ve started using a synthetic underlayment like Sharkskin or even just a dedicated drainage mat on my newer builds. It creates a small gap so the metal isn't sitting directly on the wood. Without that capillary break, the condensation doesn't just evaporate into the air; it sits in the junction where the metal meets the lumber and rots it from the outside in. If you’re building somthing you want to last more than twenty years, you need some kind of barrier to keep that moisture from soaking into your framing every time the dew point shifts.

I’m a total newbie here so bear with me, but these conflicting views are making my head spin. If I build a cold shop now with no wrap like the first guy suggested, but then decide to finish the inside and heat it later, am I asking for trouble? I honestly don't know if you can even add a barrier once the metal is allready screwed down. Does the "breathing" logic totally go out the window once you throw fiberglass or foam against those panels?

Have you ruled out the quality of your fasteners as the main culprit for that mold? I've seen guys blame a lack of house wrap when the real issue was cheap washers that dried out and cracked after three seasons. If those EPDM seals fail, you’re letting water sit right on the girts regardless of airflow. Also, for the person thinking about heating it later, have you looked into using a localized bubble insulation or a drip-stop felt applied to the metal? It seems like we're assuming it’s an all-or-nothing choice between bare wood and Tyvek, but there are middle-ground products designed specifically to handle that condensation without trapping it.

You're spot on about the condensation risks. I've seen way too many guys treat a cold shed like a house and pay for it later. One thing people often overlook when they skip the wrap is the girt spacing itself. If you're going without a barrier, I always tell people to slightly bevel the top edge of those horizontal 2x4s. It's a tiny detail, but it prevents any stray moisture from pooling on the flat wood surface, letting it roll right off the 'breathing' side of the metal.

While the discussion regarding condensation is certainly valid, I find that many installers overlook the phenomenon of capillary suction at the overlapping seams, where the minute gap between two adjacent metal panels can acutally draw moisture upward against gravity during a heavy wind event. To mitigate this without resorting to a full building wrap that might impede the neccesary drying potential of your SPF members, I typically advocate for the application of a thin strip of EPDM or a similar inert gasket material along the top edge of each horizontal girt to provide a physical thermal break and moisture barrier at the specific points of contact where the metal is fastened.

Quick update — I went out and checked a neighbor’s five-year-old shed after reading the comment about the EPDM seals. A few of his washers are alredy starting to dry rot. Now I’m wondering if the mold issues some of you mentioned are acutally caused by these cheap fasteners leaking rather than the lack of house wrap itself. Has anyone seen a specific brand of screw that actually holds up?