In this video, This Old House general contractor Tom Silva shows how to bolster a wobbly post with a single screw.
Steps for repairing a loose newel post
- Wedge a temporary wood brace between the nearest wall and newel post; the brace holds the post tight against the stair tread.
- Use a drill/driver and ¾-inch-diameter spade bit to drill a ¼-inch-deep counterbore hole into the post. Be sure the hole aligns perfectly with the stair tread against the opposite side of the post.
- Drill a screw-shank clearance hole into the post with a standard-length drill bit. Hold a layout square against the post and use it as a visual guide to ensure you're drilling perfectly level and straight.
- Switch to an extra-long bit of the same diameter as the screw-shank-clearance bit, and drill a hole completely through the post and just barely into the end of the stair tread.
- Next, drill a screw-pilot hole into the stair tread using an extra-long bit that's slightly smaller than the diameter of the screw.
- Drive the long screw through the post and into the end of the stair tread.
- Remove the temporary brace.
- Use a putty knife to apply wood putty over the screw head. Allow the putty to dry, then apply more putty to overfill the hole.
- Once the putty has dried, sand lightly, then prime and paint the putty.