Arches

Making an arch Profile

For all the how too's on making an arch profile go to the Arch profile making page

Setting out an arch that is going to be face brickwork.

If you are going to be bagging the arch (bagging brickwork) the brickwork should also be laid as face brickwork as it will be seen through the bagging.
You need to mark out the gauge on the arch profile/template for the voussoirs (glossary), prior to laying.

Lay the voussoirs in progression up the arch profile as the string line goes up for each course, this will keep the voussoirs in line with everything else.

Cutting in.

Cutting in the spandrel (glossary)
You will have to cut the bricks to fit with a diamond brick saw or angle grinder, if using an angle grinder fit it with a diamond blade as they are cheaper in the long run.

Measure the distance between the last brick laid that didnt need cutting in the course, and the nearest point of the voussoirs.

Measure the top.
In the example, I have measured the top of the brick to determine the gap, which is 170mm, minus 20mm for 2 x 10mm mortar joints at each end.
Mark 150mm on to the right hand side top of the brick, have the brick oriented the way it is to be laid to avoid any confusion when marking for the cut.

You have to measure along the string line to be accurate.



Measure the bottom.
Do the same with the bottom measurement which is 50mm, minus 20mm for 2 x 10mm mortar joints at each end.
Mark 30mm on to the right hand side bottom of the brick

You have to measure 10mm up from the brick below, the thickness of the bed joint, for the cut to be accurate.

Ready for cutting

The marked brick should look like this, ready for cutting, place a cross on the waste piece.
Cut on the waste side of the mark.

Even joints all around.

When the cut brick is laid it should have an even joint on all 3 sides, as in the picture.
This arch was eventually bagged. (bagging brickwork)



When the arch has gone off (set), usually the next day, take out the arch profile and clean up the inside of the arch.
The underside of the arch is also know as the intrados and/or soffit. Glossary

Some waste pieces can be laid if they fit, as in this picture.

Various set ups for Arches.

This arch was rendered, so no real care was taken building it, just as long as it is structurally sound.

Gauged Arch

Here is a gauged arch I did for myself at home on a new wood fired pizza oven.
The arch was set out onto a board first to make sure it would all work and to get the angle of the cuts.
Also see Wood Fired Pizza Oven Number 2

Rough Arch

The arch below is referred to as a rough arch, the term is an old one and refers to the fact that the voussoirs have not been rubbed to shape so as to form a gauged arch, a gauged arch is one where the the joints in the arch are all parallel 10mm and the voussoirs is wedged shaped.
Gauged Arch
A gauged arch is where all the arch perpend joints are parallel and not wedge shaped. see glossary

Some older arch set ups.

Relieving Arch

These were popular in years gone, the theory is that it takes the load off the brickwork underneath the arch.
How, I dont know?



And another one

Bulls Eye

Primarily used around round windows or openings.
A nice example is below, the voussoirs have all been cut or rubbed so the perpends are parallel and not wedge shaped.

How to work out arch load bearings?

A very interesting website.

Arch Load Bearing working out stuff (cache)

Arches Fail Because.

One of the main causes of arch failure is lack of lateral or sideways thrust to the arch.
Gravity wants the arch to fail so the arch needs the lateral support to stay up.

Ground movement if present will crack an arch, this can be seen on arches where one side of the arch has dropped a little.

Lack of brickwork over the top of the arch.
Ive seen arches constructed with just voussoirs and nothing else, usually in gardens as a feature, but they are usually cracked right through.