I'm building a garage/workshop, 24x40, framed 16" OC. I was thinking about using 3/8" 4x8 'SmartSide' panels for the siding, knowing it takes more effort to caulk & insure there is no way for moisture to get to the OSB. As a matter of fact I'm thinking about painting the inside of the panel before hanging it, because of the cars bringing in moisture during rain & snow.
I live in Central Pa. and usually the weather is decent; i.e. no hurricanes, no tornadoes, etc. But, I'm wondering, will 3/8" be thick enough & strong enough? I don't plan on doing anything else except frame & nail directly to the studs? Any opinions or experience with the 3/8"?
Its actually just fine. It is commonly used as the structural sheathing/siding for new homes. It is easy to seal on the vertical edges with caulk at the shiplap. If you have horizontal edges the best way to seal that is to overlap the top sheet over the bottom (z-bar flashing works but I've seen it also cause problems on numerous homes, horizontal battens over the seam is just asking for problems). Overlapping the top sheet doesn't look as bad as it sounds...It is a thin product so the overlap doesn't stand out much at all...Very common in new construction.
Nail your siding using 8d ring shanks. You must nail the sheets' edges at 6"oc and the field at 12" oc.
Painting the back side of the siding is unnecessary overkill in my opinion.
Most of the problems associated with this sort of product are not caused by the product but by the lack of maintenance (removeal of old caulk and re-caulking as needed, paint, etc.).