Technical Booklet H Stairs Ramps Guarding and Protection from Impact·Page 27·3.14
Open rises in private stairs
Private stairs may have open rises if treads overlap by at least 16 mm and a 100 mm diameter sphere cannot pass through the openings.
A private stair may have steps with open rises, but the treads should then overlap each other by at least 16 mm. See Diagram 1.1.
A private stair which has open rises, should be constructed so that a 100 mm diameter sphere cannot pass through the open rises.
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