There are many uses for a fire brick arch, whether on a fireplace or on a brick oven in the backyard. Building with brick is a tedious task, though it does not require special schooling. You'll need a few special tools to complete the task.
Measure the height and width of the space where the arch is to be installed. Transfer those measurements to a piece of ¾-inch plywood.
Cut the plywood to size. Measure and mark the halfway point on both sides of the height of the plywood. This will be with point where the arch will begin.
Measure and mark the halfway point of the width of the plywood.
Tie a long piece of string to a pencil.
Place the end of the string on the bottom mark of the plywood. Hold this in place. You may wish to place a nail in the mark, and tie the string around the nail. Extend the pencil out to one of the side marks. Remove any slack in the string.
Move the pencil from the first mark to the mark on the opposite side. The pencil will create an arched line on the wood. Cut along this line.
Wedge the template into place where the brick will be installed. Hit the wood with a rubber mallet to force it into place.
Stack bricks underneath the wooden template to hold the template in place at the height needed. Use wooden shims to fill the gap where a full brick will not fit.
Place the first brick on top of the existing brick. Cut the existing brick with a hammer and chisel if needed. The first brick of the arch should be resting on the wooden template. Do not apply mortar to the wooden template. Repeat with the other side.
Fill the gaps between two bricks with mortar.
Place additional bricks on top of the wooden template. Work back and forth until you reach the centre. You will need to hammer the last brick into place with a rubber mallet. The arch will cause spacing between each brick at the top. The bottoms of the bricks will be touching each other.
Fill all gaps with mortar. Wipe away excess mortar with a dry towel. Allow the mortar to completely dry before removing the wooden template.