FORMING METHOD FOR EXPANSION JOINT

PROBLEM TO BE SOLVED: To easily form a proper expansion joint irrespective of the thickness of a mortar layer applied on the external wall surface of a concrete building frame. SOLUTION: When a concrete building frame 4 is formed by placing concrete, a groove-shaped recess part 22 cut-out for a part to be additionally placed and for fitting of a joint bar 28 is preformed using a concrete-placing form material 20, and the joint bar 28 is placed in the recess part 22, matching the amount of the joint bar 28 to be projected from the external wall surface of the concrete building frame 4, to the amount of thickness of mortar to be applied. At this time, the amount of the joint bar 28 to be projected is controlled with a projection-controlling member 24 which is laid between the joint bar 28 and the bottom surface 22b of the recess part 22. A fitting member 26 for the joint bar 28 is provided between the projection- controlling member 24 and the joint bar 28. This fitting member 26 is engaged with the both side parts 22a of the recess part 22 by its resilience and is fastened and secured thereto. Grooves 22 for engaging the both side ends 26a of the fitting member 26 are preformed at the both side parts 22a of the recess part 22. The joint bar 28 using a foamed resin material can be also utilized as the back-up material of sealing material.