An arched doorway or window in your home creates a smooth, elegant look and eliminates the boxy appearance of traditional gaps. However, these arched areas can be tricky when it comes to moulding installation. Moulding softens the appearance of the archway and creates a definite finish to the area, but you must use a particular, flexible type of moulding to curve around the arch. Proper cutting and installation is key to securing this flexible moulding in place.
Set one end of a length of flexible moulding at the base of the archway. Have someone hold it in place or secure it with a heavy object so you can stretch the moulding all the way around the arch.
Push the moulding all the way around the arch to get an accurate measurement for how much you need to cover the archway. When you reach the other base of the arch, make a mark with pencil to show where you need to cut the moulding to fit.
Cut through the marked section with a mitre saw to make the moulding fit. Wear protective goggles and a dust mask when cutting; like wood, the moulding will produce dust and small pieces of shrapnel.
Spread a thick bead of construction adhesive along the back of the cut piece of moulding. Set the moulding firmly at one end of the archway and apply firm pressure all the way up and around, securing all areas of the moulding to the archway.
Wipe away any adhesive that leaks from the edges of the moulding with a damp sponge. Don't allow the excess adhesive to dry as it could stain the wall or window.
Hammer in 1-inch finishing nails along the front and back edge of the moulding, working every 6 inches around the archway. This will ensure proper bonding and take some of the stress off the construction adhesive.
Flexible moulding is generally most bendable between 60 and 80 degrees Fahrenheit. Allow your moulding to adjust to this temperature if necessary before installation. Some moulding manufacturers will require you to measure the area before ordering your moulding. Follow their instructions specifically regarding where to take measurements for an archway, as it often involves multiple measurements. If you want to paint your moulding, do so before installation to avoid paint drips.