How To Build A Newel Post: DIY Stair Detail

I built this decorative newel post to add architectural interest to a half wall at the base of the stairs in our Illinois house. It’s not a structural post – just a simple box built from MDF and basic trim, designed to give that clean, built-in look. It turned a plain stair wall into a more intentional architectural feature.

Materials Used

2×4 lumber
MDF panels
1×2 pine boards
Trim molding (angled profile)
Finial(s)
Wood glue
Finish nails or nail gun
Primer and paint

Tools Required

Miter saw or hand saw
Drill/driver
Nail gun or hammer
Caulk gun (optional)
Paintbrush or roller
Sandpaper or sanding block

Step-by-Step Instructions

1. Build the Post Frame

Attach two 2x4s vertically to the end of the stair wall.
This forms the interior structure of your post.

2. Box It In

Wrap the 2x4s on three sides with MDF to create the outer post shape.
Secure the MDF with wood glue and finish nails.

3. Prime and Paint

Prime and paint the boxed post before adding any trim details.
This step is easier when the surfaces are flat and unobstructed.

In-progress DIY newel post showing 1x2 trim detail and raw MDF construction

4. Add a Stacked Base

Cut and attach additional MDF around the base to create a layered, chunky profile.
This gives the post more presence and weight visually.

5. Add Trim Details

Apply 1×2 pine boards around the base and midsection for extra definition.
Simple butt joints are fine — no need for fancy joinery.

6. Apply Trim Molding

Install a piece of angled trim molding around the top of the post.
It’s not crown molding, technically — just a basic trim style that adds a nice finish.

Partially built newel post with primed trim and stacked MDF base before painting

7. Cap the Top

Cut a square piece of MDF to serve as the post cap.
Make sure it overhangs the trim slightly for a finished look.

8. Add a Finial

Attach a wooden finial to the center of the cap.
I added a second, smaller finial on top of the first one because the flat top didn’t look right to me.

Nearly complete newel post with first finial installed and unfinished stacked base detail

9. Final Touches

Prime and paint any new trim or additions.
Fill nail holes and seams with caulk or wood filler as needed.

Finished Look

This decorative newel post gave a boring stair wall an intentional, custom-built look. It’s a simple project that makes a big impact — and it still holds up all these years later.