How to Cut Molding

First measure where the molding will go. Molding typically comes in 8-foot (2.4-meter) lengths; however, some is available in 10- or 12-foot (3- or 3.7-meter) lengths, so you'll need to choose your molding before you can determine how much you'll need.

It's important to round when measuring. For molding that will go around the room's perimeter, round all measurements up to the next largest foot to allow for cutting and trimming of the pieces. For example, if one wall measures 8'3", round up to 9 feet (2.7 meters) when making your calculations [source: Royal Mouldings].

Be as precise as possible when measuring, and then divide the total by the length of the molding and add 10 percent more to the total to account for bad cuts [source: Stimpson].

Measure each corner wall angle to help calculate the correct miter angle. Some walls meet in unusual angles. It isn't unusual for supposedly perpendicular wall angles to be off as much as 3 degrees. While this may not seem like a big deal, if it's not taken into account before mitering the molding pieces, you can end up with a big gap between the pieces and have to make the cut again.

Before cutting, measure twice and test-cut the angles on scrap pieces of molding. When working on corners, measure the length needed to cut the shortest side of the molding. The top of the molding will be shorter for an inside corner; the bottom of the molding will be shorter for an outside corner. Measure again before making the final cut [source: Louisiana Pacific].

If two pieces are fairly close to fitting together, acrylic caulk can be used to fill the gap. Paint can even help make the gap disappear [source: Anderson].

Sometimes the trickiest part is cutting molding on an angle. Find out how on the next page.

Before making the first cut, a number of things have to be considered.

What kind of trim are you cutting? Different trims require different positions in the miter box or on the saw:

Which piece are you cutting? Each molding joint has a left side and a right side. For a left-hand cut, most of the molding will be to the left of blade (when the finished side of the molding is face up, bottom down). For a right-hand cut with the trim in the same position, you're cutting the right side of the joint [source: Royal Mouldings].

What type of joint are you cutting? Spliced joints are 45-degree cuts. Coping joints require both a 90- degree and a 45-degree cut. Depending upon the tool used, mitering can allow more precise cutting. Because crown molding is installed at an angle to the wall, the angle of the molding needs to be taken into account. Detailed charts that specify settings for the saw's bevel angle and miter angle are based on the angles of the walls [source: DEWALT].

To find out the key tools you'll need to cut molding, read on.

Following is a list of some of the tools you will need when cutting molding. Each particular project and the depth of the molding will determine the particular tools required, so you may need additional tools depending on your project:

You'll also need a few more items, including glue; some experts recommend gluing together molding joints before installation. If you will be employing the coping technique to join molding, you'll need a coping saw. For 45- or 90-degree angles, you might want a miter box and handsaw.

To determine the angle created by the walls, you'll want an angle gage or 360-degree adjustable protractor. A power miter or compound miter saw will allow for more angle adjustments, some for both the miter and the bevel. Use one that's equipped with a carbide saw blade that has 80 teeth or more. Make sure the saw is square and the table angle gage is accurate. If the gage is off by as little as 3 degrees, you can end up with a big gap in the miter joint. An angled filler strip is designed to fill the space behind crown molding. The filler strip is nailed to the top wall plate that runs horizontally behind the drywall, just below the ceiling. Use the strip to nail the crown molding in place. And finally, you can use some spray furniture polish to lubricate the saw blade and make cutting easier [source: Royal Mouldings, Carter, Anderson, Louisiana Pacific].

Now, you're ready to take on your molding project and even know how to cut it properly. But if you still have questions, visit some of the links on the following page.