Frank Rinn

Executive Director | ISA Germany

Frank Rinn, physicist and innovator from Heidelberg, Germany, is internationally recognised for developing pioneering tools to assess trees and timber. In the 1980s he created resistance drilling, a breakthrough that led to the invention of the RESISTOGRAPH® and ARBOTOM®, now used worldwide to detect decay, evaluate wood condition, and support conservation. Through his company RINNTECH, Frank has inspected thousands of trees and timber structures across the globe — from historic monuments and churches to bridges and sports halls — and is often called on as an expert witness.

Alongside his technical work, Frank is a leading voice in arboriculture and timber safety. He has published widely, lectured in more than 30 countries, and helped shape international standards for tree and timber inspection. As Executive Director of ISA Germany since 2001 and a former ISA Board member, he continues to advance best practices that protect both heritage structures and urban trees.

Keynote talk title: Biomechanics of trees

Mature urban trees should be kept as long as possible due to many reasons. But, these trees commonly have defective stems and require a risk assessment.

The two major VTA („Visual Tree Assessment“) thresholds (t/R > 1/3! and H/D<50!) are mostly not applicable and generally not relevant for such trees. The same applies to the SIA method („Static Integrated Assessment“), because it is fundamentally impossible to determine wind load and cross-sectional load carrying capacity with reasonable precision and reliability. Instead, Allometric Self-Referencing (ASR) allows to easily determine the relative change of the (unknown!) safety factor of trees – based on principles of tree-biomechanics, scientifically well explained by Niklas, Spatz, Telewski & Co.