In some cases, visual inspection alone is not sufficient to determine whether a tree has internal decay or structural compromise. When internal defects are suspected, Seattle Tree Consulting offers advanced diagnostic testing to help quantify the extent of decay within a tree.

We utilize a resistance microdrill (resistograph) to perform detailed internal assessments. This tool uses a very small-diameter, long drill bit that penetrates the cambium and heartwood while measuring resistance as it advances through the wood. The collected data is recorded and exported as a graph, allowing us to evaluate wood density, identify areas of decay, and better understand the remaining structural integrity and load-bearing capacity of the tree.

Resistance drilling is particularly valuable for:

• Evaluating mature or heritage trees that clients wish to preserve
• Assessing trees with suspected internal decay or fungal pathogens
• Investigating groups of trees in forested settings where structural integrity may be compromised

This diagnostic method provides objective data that supports informed decision-making regarding tree retention, pruning, or removal.

Please contact Seattle Tree Consulting for a quote or to discuss whether advanced diagnostic testing is appropriate for your site.