Sheathing provides lateral rigidity and a weather barrier to the exterior of a home. It also provides a clean surface over which to apply siding. We used ½’’ OSB (Oriented Strand Board, I had always just called it particle board) over the walls. We also had about 180 square feet of MDF siding that we used on the north face of the house as sheathing. We were given this siding as a bonus when we purchased our floor joist lumber from a gentleman on Craigslist and as it was stained and generally unattractive (albeit unused), we decided to use it as sheathing.
Sheathing is generally not a complex process. I was tipped that we should allot a 1/8’’ spacing between sheets as OSB can expand/contract with weather. Due to our ample window coverage, we were not able to use precisely 24’’ OC spacing for all studs and therefore were required to make many more cuts of our sheathing that is generally required. This still did not greatly increase the difficulty of a fairly simple process.
Sheathing is also the time to find out just how square your framing job turned out. I walked around the house and checked myself with a framing square and carpenter’s level before I began sheathing. I did find a few minor adjustments to make while placing the OSB (OSB and plywood are made by machine and are near perfectly square. Assuming your framing is correct and there’s a problem with the sheathing is like blaming your calculator for errors).