Use heavy-duty lag bolts or structural screws (often 6-inch) secured directly into the floor joists or solid bracing.
For a step-by-step visual on achieving a professional-grade installation, check out this guide on securing newel posts: How to Tighten a Loose Newel Post | Ask This Old House This Old House YouTube• Feb 3, 2020 Other Possible Interpretations 9710mp4
Cut the post to length and pre-drill holes to prevent the solid oak from splitting. Use heavy-duty lag bolts or structural screws (often