Sheathing
Sheathing is the plywood on the outside of a home that is attached to the stud wall.
On the outside of the wall we apply Plywood or a similar material like OSB to protect the home and to give lateral strength to the wall.
On the inside of the stud wall we place drywall to give a nice appearance on the living space side.
When you apply Plywood Sheathing to the outside of a home it comes in 4×8 foot pieces.
Plywood like 2x4s has directional strength built into its layers at the factory. You should install it so the length matches the height of the studs. When in doubt look for an arrow printed on the side.
When it is nailed to the plywood it is best if construction adhesive is used but it is not totally necessary.
Nails should be 6 inches on center running up and down the stud wall which can be tricky since you can’t see inside the wall. It is often best to check the plumb and bow of a stud wall before you apply the plywood.
Some contractors will apply the plywood before lifting the stud wall into place. This is a good solution if you have more then a few men to help lift the wall. If not you can build the stud wall and then apply the plywood after.
Lateral Movement.
The plywood helps stabilize the wall so that it will not fall down like a deck of cards in a storm or earth quake. It is important to know your seismic stress loads for your location when building the stud wall and applying the sheathing because you may need to add additional bracing or brackets.