noun
riser; rise
Architectural term for the vertical part of a step or stair. Used in building and construction contexts.
階段の蹴上げの高さは15センチに設定した。
The riser height of the stairs was set to 15 centimeters.
蹴上げが低いと、階段を上りやすくなる。
If the riser is low, the stairs become easier to climb.
踏み面 refers to the horizontal tread of a step, while 蹴上げ is the vertical riser.
Compound of 蹴る (keru, 'to kick') and 上げ (age, 'raising'), literally 'kick-up', referring to the vertical part of a step that one's foot kicks against when climbing.