Shear Walls
A Shear Wall is basically a stud framed wall, covered by a sheathing like plywood. The wall is covered by plywood on inside of room and outside. Make sure the joints are staggered on separate studs. This is to help with lateral forces (wind, earthquakes). They are an extra step to safety and are becoming more common.
In my case shear walls cost me extra money not only in materials but inspections. King County requested that I have a third party inspector inspect my shear walls and sign off on them. Then I had to have the county inspector come out and see that the other inspector had sign off so he could. This seemed like another ridiculous step the County made me do in the building process. I did not understand why, but hey I had a house to complete and moved on. Just make sure you check your building permit details for Shear Walls. Mine was stapled to my plans and not read until it was time for inspection. It stated structural observation required. IBC 1709 Double sided shear wall construction. The owner shall employ a registered design professional to perform structural observations as described in section 1702. So to sum up make sure you read everything that is stapled to permits.