A Page Out of the Foam Book

In the wide and varied world of wood trim, everyone looks up to crown molding--and not just because it runs along the tops of the walls at the ceiling. This powerful architectural accent can change the look of a room without overpowering other elements.

While crown molding has graced cottages and castles alike for centuries, it’s relatively uncommon in modern homes. Why? Because installing it is both difficult and time-consuming.

Wood crown molding must be nailed to the wall and ceiling at an angle. That means tricky compound-angle miter joints have to be cut where the molding turns an outside corner. Inside corners are only slightly less troublesome, requiring another compound-angle joint or a coped cut--both are fussy-fitted joints. And at about $2 per linear foot for simple 4 1/2-inch pine crown, making mistakes can get expensive.

Fortunately, there is a fast, foolproof way to put the classic beauty of crown molding in your home, and it doesn’t require a single angled cut.

The beautiful dentil crown molding shown here is from Style-Mark’s collection of architectural millwork ([800] 446-3040). It looks as if it’s made of solid--and expensive--mahogany, yet it’s actually molded out of lightweight, high-density urethane foam.

The premolded inside and outside corner blocks ($11 each), which eliminate the need to cut corner joints, are the real advantage of this system. The corner blocks simply are nailed up and then the crown molding is square-cut to fit tightly in between.

Small urethane divider blocks ($4 each) that simplify the joint between two lengths of molding on a long wall are also available. The 1 1/4-inch-thick blocks are nailed between the lengths of molding, eliminating the need to perfectly align the ends.

Style-Mark offers nearly 80 different decorative moldings, including 20 styles of crown that come in both 8- and 12-foot lengths. Most of the profiles are available in a stainable wood-grain finish or in paint-grade white, which resembles traditional plaster moldings. The stainable dentil crown we installed (No. MLD431S) costs about $4.75 per linear foot. The same profile in paintable white runs $4.

Seven Crowning Steps

You can save yourself some time and trouble by painting or staining all the molding and accessories before installing them. No primer coat is needed for painting; the preprimed white moldings accept any good-quality latex or oil-based paint.

Finish the molding with a thick-bodied gel stain or controlled-penetration stain, such as Zar Wood Stain ($9 per quart), which is made by United Gilsonite Laboratories ([800] 845-5227; https://uglproducts.com).

Don’t use a semitransparent stain; it’s too thin to tint the nonporous urethane. Apply the thick stain with a 1-inch-wide brush, covering each “tooth” in the dentil pattern. Then begin the installation by nailing up all the inside corner blocks with 2-inch (6d) finishing nails. If the wall corners are out of square--and most are--you’ll need to slip thin shims behind the urethane corner blocks to fill the gaps. If there are any outside corners in the room, nail up the outside corner blocks the same way.

Next, carefully measure the distance between two corner blocks. Add one-eighth inch to that dimension and cut a length of crown molding to match. The most accurate way to crosscut the molding is with a power miter saw or radial-arm saw, but we got excellent results with a fine-tooth handsaw. To produce a square cut, clamp a short 1-by-4 to the molding and use it as a saw guide.

Hold the crown molding in place with one end tight against a corner block. Bow it slightly, insert the other end and press the molding to the wall until it pops into place. Secure it with 2-inch finishing nails driven into every other wall stud. Also nail up into a ceiling joist every few feet.

Can’t find the joists? They may be running parallel to the molding. In that case, an angled nail up into the drywall or plaster ceiling will usually suffice.

If two lengths of molding are needed to complete a long wall, nail a divider block between the two pieces. Continue cutting and installing molding to fit between the corner blocks. If you cut a piece too short, rescue the situation by filling the gap with a matching caulk.

Once all the crown molding is up, set the nailheads and fill the holes using a crayon-type putty stick. Wipe off excess putty with a damp cloth, then stand back and revel in your crowning achievement.

Reprinted from the pages of Today’s Homeowner Magazine. To receive more expert advice on improving your home, call (800) 456-6369 or visit the Web site at https://www.todayshomeowner.com