A newel is an end post for a banister or stair rail. These posts are typically as much decorative as supportive and come in two basic styles. Solid turned newels are made from a single, solid piece of wood that is turned on a lathe or otherwise carved to provide decorative detail. Box newels are hollow and have applied mouldings at the top and bottom for detail. They also frequently have a carved ball or finial on top of the cap. The fitting procedure depends entirely on the style of newel post being installed.
Calculate the position of the newel post, which will depend on the railing position and the depth of the stair on which it is being placed. Position the post in place and turn it so that the correct face is turned toward the rail. Trace around the bottom of the post to mark its location using a pencil.
Center a 1-inch L bracket on each side of the post. Position it with the L perpendicular to the face of the post and the corner flush with the bottom. Mark the screw holes in the bracket onto the post. Drill 1/8-inch pilot holes in each marked spot, 1/2 inch deep, using a drill.
Drive a 3/4-inch wood screw through each hole in each bracket into the face of the newel post. Use a cordless drill to drive the screws. Set the drill in place and mark the screw holes of the other half of the bracket onto the floor. Drill pilot holes as you did for the post face and drive one 3/4-inch wood screw through each hole in each bracket.
Install the base trim around the bottom of the post. Nail or screw it in place, depending on your post and the trim package that came with it. In general, nail one mitred piece of trim to each face of the post, with the corners matching at the post corners.
Find the mounting block. Look for a solid block of wood 1 1/2 inches thick that fits snugly into the hollow base of the newel post. Position it on the step, as outlined for marking in the previous section and trace around it with a pencil.
Drill one 1/8-inch hole through the face of the mounting block, 1 inch in from each corner of the block. Position the block in the outline you marked on the floor and drive one 3-inch treated deck screw through each hole into the floor to anchor the block in place.
Fit the newel post over the mounting block. Drive one 1 5/8-inch treated deck screw through each face of the post, 3/4 inch up from the floor, into the edge of the mounting block to anchor it in place.
Install the base trim that came with your newel post. Fit one mitred piece to each face of the post base and nail it in place with 1 1/2-inch pin nails from a pneumatic pin nailer. Match the mitred corners up at the corners of the post to create a square ring of trim, covering the mounting screw holes. Use at least three nails in each piece.