When installing quarter round molding, it's important to get the joints just right. If you don't, then the appearance of the molding will not seem to flow with the length of the wall. Furthermore, working with quarter-round molding is a little different than working with flat board molding. Instead of using mitered joints, quarter round molding uses “coped” joints. These types of joints are usually found on the inside corners of interior walls. While coped joints may seem to be difficult to work with, they are actually not.
Install First Molding Run
First, cut a length of quarter round molding that runs the complete length of one wall. When working in a room with four corners, the best area to place this particular piece of molding is on one of the two walls that is adjacent to the wall, where the doorway is located. Attach the quarter round molding to the base of the baseboard.
Molding for the Doorway Wall
Cut another length of molding that fits between the doorway opening and a piece of quarter round molding that you just installed. Make sure to cut this piece about 12 inches longer than it needs to be. You will need to use a coping saw to cut one end of this piece so that it will fit around the piece of molding that you place on the adjacent wall. The extra 12 inches is to allow for any mistakes that you might make while using the coping saw.
Preparing to Make Coping Cuts
Next, trace the basic shape of the quarter round molding onto the backside of the molding with a pencil. You may also choose to scribe this curved line if you like. Make sure the drawing of the curve is facing the right direction.
Making the Coping Cut
Next, use your coping saw to cut out the curve that you drew on the backside of the molding. It is best to make cuts that are perpendicular to the length of the quarter round molding itself. However, in some cases, you might find it a little easier to angle the cut slightly. In this case, the angle might actually approach something like 60 degrees.
Preparing the Opposite End
Next, use your miter saw to cut the other end of the quarter round molding. Adjust the fence on a miter saw to allow for a 45-degree cut. This piece of molding should fit neatly up against the edge of the door trim. Likewise, the opposite end should curve neatly around the piece of molding that it is butted up against.
Repeat the process in step one - for the other wall that runs adjacent to the wall with the doorway.
Repeat the process in steps two through five for the lengths of molding that will be placed on the other side of the doorway.
When installing the molding on the final remaining wall, place a length of quarter round molding that is coped at both ends so that it fits precisely between the molding that is installed on the adjacent walls. You can do this with a single length of quarter round molding, or you can piece two pieces together using a 45-degree miter cut.
You should have now successfully installed quarter round molding. As you can see, installing quarter round molding is not difficult; it just takes some patience and a little bit of skill using the coping saw. Before attempting to install quarter round molding, it is usually a good idea to practice making coping cuts on a few pieces of scrap molding or thin lumber.