1. Burnt Brick Walls
Perhaps the most standardised form of small-element masonry that has been with us for thousands of years is the fired clay (ceramic) brick wall. The individual bricks are glued together with lime or cement mortar to form a network of horizontal and vertical joints, which also form the pattern of the brickwork. The different standard sizes were all based on the same formula: the length of a brick is twice its width plus the size of the joint. For example, a small brick measures 25 cm x 12 cm x 6.5 cm while a large brick is 29 cm x 14 cm x 6.5 cm.
The positioning of the bricks within the wall can be either stretcher or header. The longitudinal side of the stretcher is parallel to the wall, and the longitudinal side of the header is perpendicular to the line of the wall.
General rules for brick bonding:
- The size of the bricks and the height of the mortar layers must be the same in each course.
- The elements must always be laid with overlapping.
The overlap should be at least ¼ brick length in the length of the wall and ½ brick length in the thickness of the wall.
- Avoid using quarter or smaller elements unless absolutely necessary.
- In alternating courses, the centre line of the brick in the bonded position must coincide with the centre line of the stretcher course above and below it.
- In alternating courses, the vertical joints shall form a vertical line.
- Stretcher courses are used only on the visible part. Inside the wall, only header bricks are allowed.
The most typical load-bearing wall thicknesses are one-brick thick (25 cm), one-and-a-half brick thick (38 cm) and two-brick thick (51 cm).
The one-brick thick wall can be constructed:
- only from stretcher courses with quarter offset,
- only from header courses with quarter offset,
- and the alternation of the two types of courses, called the English Bond Wall.
The most common one-and-a-half brick thick wall, and the much rarer two-brick thick wall, are built with the courses on the outside, every or every second row. Wall joints such as wall ends or wall corners are typically solved by using three-quarter elements (bats).
2. Stone Masonry
Stone walls also have a very long history, but they are costly to carve and thermally unfavourable. Now, they are mostly used as fence walls or as pedestals, for example.
In their oldest form, they were laid dry without any binders. This is called the dry stone wall.
Binder stones are typically made of lime mortar.
Non-carved stones are known as rubble stones, and can be built in non-stratified (cyclopean) or stratified layers.
The masonry rules are similar to those for brickwork:
- vertical joints must not overlap;
- each stone must rest on at least two other stones;
- as many binding stones as possible should be installed through the thickness of the wall.
Ashlar stones are typically built from regular rectangular carved stones of the same size, typically with the same course height and matching vertical joints in every other row.
In addition to mortar, grooved, stone-pin, metal-pin and metal-spike joints were also used.
