How to Make a Crown Molding Border on a Whirlpool Tub

Measure the sides of the tub. Measure along the point where the tub meets the wall. There will be three measurements -- one long measurement where the side of the tub meets the wall and two shorter measurements where the ends of the tub meet the wall.

Mark the measurements onto vinyl trim board with a pencil.

Don a face mask and protective eyewear.

Cut the vinyl trim boards to the appropriate length, using the pencil marks as a guide. A number of saw types are suitable for this project, including table saws, hand saws and circular saws.

Place each piece of trim on its side and use a pencil and protractor to mark out a 45-degree angle at both ends of the long piece of trim and on one end of the two short pieces, where the short trim segment will meet the long piece of trim that extends along the tub side. The cut will extend from front to back. Once the cut is complete, the front side of the trim board will be slightly shorter than the back side of the trim board.

Cut the 45-degree angles into the ends of the trim, using the pencil marks as a guide.

Arrange the trim on a table or work bench. Position the trim in the same way that it will be installed so you can match up the corners to verify that the angled cuts are accurate. If necessary, cut a new piece of trim.

Install the molding around the tub. The crown molding will be positioned upside down, with the thicker portion of the molding at the bottom. Hammer in a finishing nail 1 or 2 inches away from the tip of each molding segment and hammer in additional nails every every 6 to 8 inches along the length of each segment.

Place the bottle of caulk in the bottle holder portion of the caulk gun and cut off the nozzle tip using a razor knife. Cut the tip at a 45-degree angle.

Apply a dab of caulking over each nail head to conceal the nail head and seal out water. Wipe off excess with a damp paper towel and use a wet finger to smooth the caulking.

Apply a line of caulking along the top and bottom edges of the molding. Wipe off excess with a damp paper towel and smooth the caulking with a damp finger or a caulk smoothing tool.