Department of Building and Housing - Practice Advisory on Egress Stairs
From the DBH's website:
This Practice Advisory is to:The Advisory can be found here.
It applies to all existing multi-storey buildings throughout New Zealand:
- alert practising structural engineers assessing existing multi-storey buildings throughout New Zealand to issues relating to safety of stairs
- to which members of the public have access, including office buildings, particularly those with scissor stair configuration, and
- have stairs designed to slide under seismic action, particularly those with the gap-and-ledge stair detail.
- If the relative lateral displacements between adjacent floors of a building (the “inter-storey drifts”) are sufficiently large, a stair may be pulled off the ledge that supports the sliding end of the stair.
- The seating dimensions allowed in existing designs may not be sufficient to account for movements now expected.
- The maximum inter-storey drift in estimates of building displacement may not adequately account for variability and uncertainty.
- Details that have limited scope to allow closing movement may cause damage to the stair flights. This damage may shorten the flights and make them more likely to fall off their supports.
- Seismic gap details that have been partially or fully filled or are susceptible to being filled because of construction or maintenance errors may restrict or prevent closing movement
- Heavy finishes, fixtures and fittings in stairwells may come loose during an earthquake and fall and block the stairway or injure people using it.