What is the maximum spacing of shores for 2" thick sheeting or lagging when nonstress grade lumber is used?

What is the maximum spacing of shores for 2" thick sheeting or lagging when nonstress grade lumber is used?

• A. 2 ft
• B. 3 ft
• C. 4 ft
• D. 6 ft

Answer: (C)

Shoring and lagging must resist lateral earth pressure without excessive deflection or failure. The spacing between shores depends on how stiff the sheet and the lumber are, which in turn depends on sheet thickness and lumber grade. With 2-inch-thick sheeting or lagging and non-stress grade lumber, each shore can only support a limited amount of load, so the shores must be spaced closely enough to keep the sheet from bending or the wall from bulging under the soil pressure. That practical limit is four feet. If you go farther apart, the sheet can bow or fail to hold back the earth, especially in soils with higher pressure or moisture. Closer spacing, like two or three feet, would be more conservative; six feet would exceed what this material can safely handle.

Shoring and lagging must resist lateral earth pressure without excessive deflection or failure. The spacing between shores depends on how stiff the sheet and the lumber are, which in turn depends on sheet thickness and lumber grade. With 2-inch-thick sheeting or lagging and non-stress grade lumber, each shore can only support a limited amount of load, so the shores must be spaced closely enough to keep the sheet from bending or the wall from bulging under the soil pressure. That practical limit is four feet. If you go farther apart, the sheet can bow or fail to hold back the earth, especially in soils with higher pressure or moisture. Closer spacing, like two or three feet, would be more conservative; six feet would exceed what this material can safely handle.