To get the classic upgrade of crown molding without the frustrations of detailed carpentry, put up lightweight plaster-covered foam molding. This Old House technical editor Mark Powers shows you how to do it in a weekend for less than $2 per foot.
1. Line the molding up with a door or window casing, making sure it looks level. Make a reference mark to note its alignment
2. Using a miter box and handsaw, cut the molding. Place the molding upside down in a miter box, braced against the side and bottom at an angle, and cut it with a handsaw.
3. For corner joints, cut the molding at a 45-degree angle. For an inside corner, make the top part of the molding shorter. For an outside corner, make the bottom part shorter. Shave the back of the cut ends with a rasp.
4. Spread joint compound along the top and bottom edges of the molding and on each cut end. Stick the molding in place. Push two mitered ends together to create the corners, making sure their profiles line up. Join two pieces on a long wall with a butt joint. On runs longer than 5 feet, support the molding temporarily with 8d nails.
5. Using your finger or a putty knife, fill any gaps with more joint compound and smooth out the seams where the molding meets the wall and the ceiling. Scrape more compound over the butt joints with the putty knife.
6. Clean up the excess compound with a wet sponge. Leave it proud of the joint, then sand it with 150-grit sandpaper once it's dry.
7. Prime and paint the molding to match the other trim in the room.
