If you've only laid out brick walls or paths previously, setting out an arch can seem a little daunting. Fortunately, you can set out brick arches using a proprietary arch former. According to City College Coventry, these are arch shaped supports manufactured from steel or plastic. Using a proprietary arch former helps to ensure a faster job and a perfectly shaped arch. They are designed to be incorporated into the arch.
Set stepladders in front of the work area. Place the former on the two columns. Ensure it spans the gap equally.
Loose lay the bricks on the former. This will allow you to work out how many you need and how best to position them. Ensure one brick is exactly on the top of the former. This will be the keystone brick. An arch with a keystone is more aesthetically pleasing.
Prepare the mortar following instructions on the bag. This varies slightly between different manufacturers. However, you will only need to add water. A 25 kg bag normally makes enough mortar for about 25 bricks.
Dip your trowel in the mortar and lift enough for one brick. Butter the side of a brick with the mortar. Lay it in place on one of the flat parts of the former. Add mortar on top of it. Lay a second brick on top of the first one. Continue laying bricks until you have reached the point where the keystone brick will go. By then, you will have formed nearly one half of the arch.
Form the other half of the arch in the same way. Butter the keystone brick and drop it in place between the two sections. Leave the mortar to “go off” or set. The time required will depend on the type of mortar. Rapid-set mortar goes off in less than an hour. Traditional mixes take longer.
You can use wedge-shaped bricks -- called voussoirs -- if you can locate them or find a maker to make them for you. This adds ornamental flair to the job.
Using a proprietary arch former helps to ensure a faster job and a perfectly shaped arch. However, you can make a removable wooden former if you wish.