How to Install Foam Molding

Mark Morris

Installing molding is one of the trickiest jobs in trim carpentry. Measuring angles, cutting miters and the expense of the material all combine to scare many people into hiring the work done. Foam moldings come in a wide variety of styles and sizes and can be had for a fraction of the cost of traditional wood moldings.

Cutting the miters for molding can be tricky.

Installation of foam moldings does not require the use of expensive nail guns. The product can be hung with an adhesive dispensed from a cheap caulking gun and the results are beautiful.

  1. Measure for foam moldings as you would for traditional wood molding. For crown or base measure the wall from corner to corner. For panel and other moldings measure the outside dimensions of the space where your want to apply the molding. Use an angle finder to get accurate corners. They can be purchased at hardware stores and home centers. Follow the directions with the angle finder. Read the angle and divide by two to get the angle of each piece for corners.

  2. Cut foam moldings with a power or hand miter saw. Hold the material firmly against the saw table and fence. Keep hands well clear of power miter blades. Use smooth cutting motions and equal pressure to cut foam with a hand miter. Rough edges can be smoothed over with sand paper. Check the fit of all joints before applying adhesive.

  3. Purchase a water-based adhesive caulk. Choose one specifically rated for use on foam. Cut the tip of the adhesive tube with a utility knife on an angle to create an opening about ΒΌ inch wide. Load the tube into caulking gun by depressing the thumb button and pulling the plunger all the way back. Depress the thumb button and push the plunger into the back of the tube. Release thumb button and apply steady pressure to trigger.

  4. Run a pencil-sized zigzag of adhesive down the back of the molding. Press the molding into place and hold for 30 seconds to allow the adhesive to grab. Repeat the process with other pieces until complete.

  5. Use painter's caulk to fill gaps in joints. Load the caulking into the gun and press the tip into the gap to be filled. Apply a line of caulk a little thicker than the gap and work it into the gap with a wet finger. Use water and a damp rag to remove any excess on the molding face.

  6. Add a coat of water based primer before painting with water based paint or stain. Avoid products with solvent or oil bases, they will eat the molding.