Measure the wall where the stucco foam molding is going to be installed. Mark the measurements on a length of the foam molding with a pencil.
Prepare the walls for the stucco molding. Use a damp rag to wipe away dust and dirt. This is especially important because the moldings will be glued to the walls. Dust and dirt can interfere with the adhesion of the glue.
Cut the stucco molding to size with a miter saw. For corners, adjust the miter saw so it will cut the depth of the first side at a 45-degree angle. Set the saw to the opposite 45-degree angle to cut the other side of the corner.
Connect the joints of the molding with a scarf cut. Stucco molding pieces may not be able to span the whole length of a wall. Set the miter saw to a 45-degree angle, as you did for the corners, but cut the ends of both stucco molding pieces at the same angle.
Set the stucco foam molding in place with the help of a partner. The molding is not heavy but the length of the molding may require two people to keep it in place while it is installed. Check the molding to ensure that it is cut correctly and fits into place.
Apply adhesive to the back of the stucco foam molding using a caulk gun. Spread the adhesive in an "s" pattern.
Set the molding in place. Wrap masking tape over the molding to hold it in place while the glue dries. Let the glue dry for 24 hour, then remove the tape.
Caulk the joint between the molding and the wall. Spread a bead of caulk in the gap and smooth it with your finger. Allow the caulk to dry for 24 hours or per manufacturer's directions.