In tree bracing, where can through braces be installed?

• A. Through braces can be installed anywhere regardless of wood condition
• B. Through braces require at least 70% sound wood
• C. It is allowed anywhere
• D. Through braces cannot be installed where there is less than 30% sound wood

Answer: (D)

Through braces rely on solid, intact tissue to hold the hardware and carry load. Since they pass through the trunk, there must be enough sound wood around the bore to anchor the bolts and transfer forces without the wood failing. If the tree has decay or weakness that leaves less than 30% sound wood, there isn’t enough healthy tissue to support the through brace, and the bore can become a new failure point or invite further injury. For that reason, installation is not performed when there is less than 30% sound wood. When at least that much sound wood remains, a through brace can be considered with proper placement and technique, but the key requirement is adequate sound wood. The other options overlook the critical condition of the wood and set incorrect allowances.