Alternating masonry

Alternating masonry, called almaşık duvar in Turkish, is a wall built with stone and brick in alternating bands. In its most common form one or more courses of dressed or roughly dressed stone are topped by several courses of brick, and the sequence repeats up the wall. In some examples each stone block is framed on all sides by vertical and horizontal bricks, a variant known as cloisonné or box masonry. The joints are laid in lime or horasan mortar.

Its role in the building

The technique became widespread in the Byzantine period and was used extensively in early Ottoman architecture, particularly in buildings around Bursa and İznik. It brings several advantages:

• The brick bands level the wall at regular intervals, helping it rise evenly.
• Two materials working together can improve load distribution and seismic behaviour.
• The contrast in colour and texture between stone and brick gives the facade a built-in ornament.

Alternating masonry in survey and restoration

A survey records the number and height of stone and brick courses and the joint thickness, and a material and decay map is drawn over a facade orthophoto. Typical problems are spalling brick faces, loss of mortar from joints and salt efflorescence. Missing bricks are replaced with new ones close in size, colour and firing; joints are repointed with a lime-based mortar compatible with the original. Cement mortar is harder and less permeable than the stone and brick, so it drives moisture into the masonry units and speeds up the decay of the brick itself. In 3D visualization, the wall looks convincing when built from real materials changing course by course rather than a uniformly repeating texture.