In Situ Density Estimation of Structural Timber Using Drilling Chips Extraction (Woodex+): Validation and Sustainability Contribution

This study presents Woodex+, a universal semi-destructive device for extracting drilling chips to estimate in situ the density of structural timber. Sixty prismatic specimens from six commercial species (four softwoods and two hardwoods) were tested, performing 360 controlled extractions using drill bits of 6, 7 and 8 mm while maintaining constant extracted volume. Specimens were conditioned to approximately 12% moisture content and both chip mass and reference density were measured. Strong correlations were obtained between chip mass and real density, with coefficients of determination R 2 > 0.70 for simple models and up to 0.90–0.95 when multi-species regression models including species as a categorical factor were applied. Drill diameter significantly affected chip recovery due to fragmentation and moisture loss at greater depths, while cutting direction (radial vs. tangential) was not statistically significant. Woodex+ improves previous prototypes in terms of compatibility with standard drills, robustness and ease of use, while maintaining low invasiveness. Its application supports structural assessment, reuse of timber elements and improved carbon accounting in sustainable renovation practice.