Work out expansion joint spacing instantly with clear inputs, formula shown and shareable results.
Thermal movement per metre is the coefficient of expansion times the temperature range, and for concrete at 12 microstrain per degree over a 30 degree range that is 0.36 mm per metre. Dividing the joint's movement capacity by that rate gives the maximum spacing, and the number of joints is one fewer than the number of bays.
Movement
mm per metre = coefficient x 10^-6 x temperature range x 1000
Spacing
Maximum spacing = joint movement capacity / movement per metre
Preliminary estimate only. Movement joint layout must be designed by a qualified engineer accounting for shrinkage, creep, restraint and cladding compatibility.
mm per metre = coefficient x 10^-6 x temperature range x 1000. Thermal movement per metre is the coefficient of expansion times the temperature range, and for concrete at 12 microstrain per degree over a 30 degree range that is 0.36 mm per metre.
For concrete, yes. Early-age drying shrinkage can exceed thermal movement and is the reason construction joints are specified far closer than thermal calculation alone suggests.
This calculator takes 4 inputs: Structure length, Temperature range, Coefficient of thermal expansion, Movement capacity per joint. The pre-filled defaults are a realistic worked example — replace them with your own site or project figures.