The segmental arch has all the same features as a flat arch except that the extrados and the intrados are both curved and radiate from the same point.
The face height is measured along any line radiating from the focal point.
The moulded bricks around the extrados (in the sketch) are called the label course and often project from the face creating a hood. This feature is often used as a weathering over an opening and can sometimes have a lead dressing over.
To specify the Segmental arch you will need to provide the following information:
Brick material (colour), span, face height, (along any joint line), camber rise (this is very important), joint width, number of voussoirs, bond pattern, soffit depth, brick finish (rubbed or sand faced).
You will also need to specify any feature, keystone or decorative detail?
Note: The radius of the arc, (the distance from the intrados to the focus), can be calculated from the span and the camber rise.
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