Brick Wall Expansion Joint

Clay brickwork will generally be subjected to long term expansion while concrete masonry aggregate blocks aircrete blocks will be prone to shrinkage.

Brick wall expansion joint.

When building a boundary wall an expansion joint is a separation designed to relieve stress on building materials caused by movement induced by thermal expansion and contraction. The coefficient of expansion or e value of clay bricks when tested in accordance with as nzs 4456 11 can vary from a very low 0 3mm m millimetres per metre to over 1 6mm m. This allows the joints to partially close as the brickwork expands. 1 3mm per linear run of brickwork should be allowed so a wall that has movement joints at 9m centres should have a joint of 12mm.

This movement could be a result of thermal expansion moisture movement creep and structural loading or the effect of chemical changes. Exterior vertical wall expansion joint selection guide emseal watertight fire rated sound proof insulating precompressed foam sealant expansion joints selection guide. This allowed movement helps prevent distortion and cracking. The expansion and contraction of masonry needs to be accommodated and controlled by the inclusion of both vertical and horizontal joints within the building.

Expansion control joints to control the expansion and protect the wall structure from cracking under pressure masons install vertical control joints at specific locations. They are therefore specifically provided in boundary walls to avoid cracks occurring in the wall. These joints will absorb the pressure created by the expansion by giving the masonry wall flexible space to expand. The joints are formed by leaving a continuous unobstructed opening through the brick wythe that may be filled with a highly compressible material.

Most general purpose bricks have a coefficient of expansion in the range 0 5 to 1 0mm m over 15 years. Prime candidates for expansion joints include long expanses of walls corners offsets setbacks and parapets. Brickwork showing wall ties spaced no more than 225mm from the expansion joint movements joints and their size vary depending on the size of the wall. Expansion joints should be located where stresses or cracks are likely to develop in brickwork.

An expansion joint in brickwork and blockwork is a means of solving potential problems caused by movement. Expansion joints should also be located below shelf angles to account for vertical expansion of brick.