Moldings are decorative trim pieces around your windows, doors, and walls. They come in a variety of materials and profiles, and when used in just the right way, they can add a bespoke personal touch to your room’s entire style. Here, we will walk you through everything you need to know about choosing or updating your home’s moldings.
Types of Moldings and Their Functions
There are four principal types of moldings to decorate different parts of a room. Let’s learn a little more about each one.
Casing
Casing has both form and function. By surrounding doors and windows, it covers the narrow shim space between the wall framing and the do covering the gap between the wall framing and the jambs. Some casings feature a two-part design, with a backband wrapping the outer edge for added detail.
Pro Tip: When installing window casing in old houses, TOH general contractor Tom Silva often has to contend with walls that dip and bulge, causing gaps between trim and wall. Rather than reaching for a caulk gun, he uses wood filler strips: “I like to leave a nice, clean edge for the painter,” he says. He rips a scrap piece of casing to a width of 1 inch, then scribes it to match the wall’s contour using a compass set to the largest gap.
Baseboards
Baseboards cover the joint between walls and flooring and are particularly common in homes with hardwood or tile floors. They help protect the edges of the wall from damage and scuffs. Some baseboards come in two pieces, with a flat board topped by a decorative base cap.
Installation Insight: To keep a baseboard tight to the floor, Tom Silva back-bevels the bottom edge, toenails each piece into the studs, and where possible, covers the joint between floor and baseboard with shoe molding. He also favors coped joints on inside corners over miters: “A coped joint is less likely than a miter to open up when the moisture changes,” he says.
Pro Tip: TOH general contractor Tom Silva recommends using wood rather than MDF for baseboards: “MDF doesn’t like to get wet. If it does, it will swell.” For that reason, he prefers half-inch poplar for any baseboard piece that will be touching the floor.
Crown Molding
Crown molding covers the joint between your walls and ceiling. It’s commonly seen in older homes, as well as on fireplace mantels below the shelf. You can purchase it in a single piece or combine multiple pieces for a built-up crown.
Chair Rails and Wainscoting
Chair rail molding typically runs horizontally about 3 feet above the floor in formal dining rooms. It can be combined with other moldings to make a wainscot that covers the lower part of the room’s walls.
Alexa Hampton, This Old House senior design consultant, is a fan of wainscoting in dining rooms: “A dining room can be difficult to decorate, because often you’ve got just a table and chairs and a sideboard. Adding wainscoting can go a long way to finishing the room.” Hampton prefers a traditional height of around 36 inches, which tends to make ceilings appear higher. “You get a nice optical illusion from the horizontal band running around the room.”
Materials Used in Molding Construction
You have a few different material choices for your molding project. Here are the three general categories you might find at your retailer:
- Wood molding: Wood has been used for molding in homes for centuries and it still stands the test of time. Pine is one of the most popular materials for molding since it’s easy to work with. You can also find poplar and alder molding that’s perfect for staining.
- Medium-density fiberboard (MDF): MDF has a smooth surface, free from natural defects, that’s easy to paint and less expensive than solid wood.
- Plaster: Intricate plaster molding was used generously in old, high-end homes. It’s still available today, but a bit less common to see.
Pro Tip: This Old House master carpenter Norm Abram points out a key advantage of MDF over plywood and solid wood: “With MDF, it’s nondirectional, so you get more efficient use of the sheet.” He adds, “With plywood, every time you expose an edge, you’ve got to find a way to cover it, but with MDF the edge is treated just like a solid piece of wood.”
Molding Installation Techniques and Tools
Once you’ve selected the right molding for your space, it’s time to install it. Use these tips to help you.
Cutting Molding
Using a miter saw is the best way to cut molding. Miters are cuts of equal angles that join trim in a corner, usually 45-degree cuts on the ends of two pieces. Miter saws can make square cuts, as well as cuts at angles between 45 and 90 degrees.
When it comes to molding, it’s best to measure twice and cut once. Accurate cuts minimize gaps and keep a seamless connection between segments.
Pro Tip: Tom Silva, This Old House general contractor, says precision is what makes miter saws so indispensable: “You can shave off little bits until you get a perfect fit.” He also notes that for making accurate miters, “first would be technique and second would be tool.”
Miters and Coping
Why Not Miter Inside Corners? As Norm Abram explained during the Arlington house project, a common mistake is mitering inside corners: “The problem with that is that over time, that joint will start to open up. So you get a big gap in the corner. So you always do butt joints in inside corners.”
Molding has both outside and inside corners. For outside corners, you’ll use a mitered joint, cutting the molding at complementary angles to form a neat corner.
For inside corners, a coped joint works better. To make one, cut a miter joint, then use the miter cut as a guide to cut out the profile of the molding your joining piece will butt against.
Pro Tip: Tom Silva, TOH general contractor, always opts for coped inside corners: “It’s the best way to make a tight joint,” he says, “but it takes patience.” Done with care, a coped joint is a carpenter’s best insurance against a gap opening up when the wood shrinks.
To cut an accurate cope, first darken the leading edge of the miter cut with a pencil so the profile line is easy to follow. Then use a coping saw — its thin, flexible blade can curve around the molding’s profile and navigate tight angles. Hold the saw level with the floor and tilt the blade back slightly to create a back cut, removing all the wood behind the leading edge. As TOH’s experts put it: “It’s just the leading edge that matters — that’s all you’re going to see.”
Nailing and Finishing
Most professionals install molding with a cordless or pneumatic brad nailer and 18-gauge nails. Then, they’ll fill the nail holes with spackle and paint or stain the molding to complete the look.
Pro Tip: TOH general contractor Tom Silva recommends a brad nailer for most trim work: “The thin, 18-gauge nails that brad nailers shoot have less chance of splitting or marring the wood surface than the thicker 15- or 16-gauge nails that finish nailers use, and brads leave a much smaller hole to fill. That can be a real advantage when installing small or delicate trim pieces like shoe or crown molding.”
Restoring Old Molding
If you’re working on an old house, you may be able to order custom molding that matches the original pattern from a specialty millwork shop.
You may also be able to remove and reuse the original molding to save some time and effort. Protect your walls from damage by inserting a shim or metal putty knife behind your pry bar. If the molding has minor damage, you could repair it with wood filler or epoxy. For more extensive damage, you may need to replace the affected section completely.
If your home was built before 1978, you should assume that the original molding installers used lead paint. When you remove the molding, follow lead-safe practices to prevent the spread of harmful dust. If you’re unsure or uncomfortable doing the job yourself, consider hiring an EPA-certified contractor to test the area and safely encapsulate the lead with new paint.
