Wall Strengths Stud Size And Spacing
by Tobe Walter
As we've talked about earlier, walls see compressive loads as they transfer vertical live and dead loads down toward the foundation. Walls also see bending loads from the wind. In this sense, each stud acts like a small floor joist. The wind pushing on a stud wall is much like furniture sitting on a floor.
A floor joist is on its edge and sees a live load from above. A stud is on its edge, but in a vertical plane and sees the wind load from the side. Stud walls must be strong enough to carry the vertical comprehensive loads and the lateral (bending) loads. Two by four and two by six studs are typically 16 inches on center. The maximum stud spacing permitted is 24 inches, but in most housing, 16 inch centers are standard. Two by fours were the most common size for studs until the energy crisis of the mid 1970s.
Two by six studs are now commonly used on exterior walls to accommodate the greater insulation levels common to new construction. While two by six studs are inherently stronger than two by four studs, the strength and stiffness is not needed. Houses were already strong enough with two by four studs. Studs have to be continuous from the top to the bottom of the wall. The only exception is a factory made, finger jointed, glued assembly (not common). A splice in a load bearing stud wall is usually a weakness. Spliced partition studs are more common.
Two by four walls with studs 16 inches on center can typically carry the load from one floor level and the roof or two storys but no roof. This assumes that the walls are not taller than 10 feet. If a stud wall is asked to carry two storys plus a roof load, it's common to go to two by fours every 12 inches on center, or two by sixes, 16 inches on center. In some areas, two by fours cannot be used to support two storys plus a roof load. Go Jereme Go Jereme Go! More Carpentry Tips in the near future