Determine the type of flexible molding you need for the job. There are three kinds: inside radius for concave curves, outside radius for convex curves and arched radius for arched curves.
Calculate the linear footage of flexible molding you'll need. Think of the curve as a half-circle. Measure its height at the center in inches, and add it to the width of the bottom, side to side, in inches. For example, if the height is 36 inches and the width is 90, the total is 126 inches. Divide by 12 to get the linear feet you'll need to buy.
Use a miter saw to cut the flexible molding so that each end will fit the molding on either side of the curve where it meets the molding for the flat surface.
Run a bead of construction adhesive in a tight "S" pattern on the back of the flexible molding. Press it gently in place and nail it in with a nail gun loaded with finishing nails, 1/4-inch from the top and bottom edges. Space the nails 4 to 6 inches apart, staggering them from top to bottom. Wipe away any excess glue with a damp rag.
Fill the holes where nails are countersunk, using vinyl Spackle. Let the Spackle dry for an hour, and then sand lightly for an even surface. Now that the molding is installed to the curve, you can prime and paint it the color of your choice.
Things You Will Need
- Measuring tape
- Miter saw
- Construction adhesive
- Damp rag
- Nail gun
- Finishing nails
- Vinyl Spackle
- Fine-grit sandpaper
- If you're concerned about cutting the molding correctly for the curved surface, draw a template of the curve following Steps 1 and 2. Take it with you when you purchase the molding, and have the store custom-cut the pieces for you.