Many locations have old stairs that need to fixed or replaced due to age, damage etc. Generally speaking regardless of the code in place when the original stair was made, you will need to update your stair to the current building code (IBC) when you replace stairs.
3404.1 General. Except as provided by Section 3401.4 or this section, alterations to any building or structure shall comply with the requirements of the code for new construction. Alterations shall be such that the existing building or structure is no less complying with the provisions of this code than the existing building or structure was prior to the alteration.
This becomes an issue when stairs are installed in tight locations under codes that vary greatly from today’s current International Building Code (IBC) variants.
Imagine having a 12’ high stair in place with a riser height of 9” and a tread depth of 9”. This stair would have (16) treads, 9”deep for a total run of 11’3”.
If the replacement stairs would be required to meet IBC code (adopted by all of the states) they would now need to have (20) treads, 11” deep for a total run of 18’4”. The IBC stairs would extend 7’1” further than the originally installed stairs.
The increased run and decreased slope can wreak havoc on your facilities if the original stairs stopped right before a hallway (new stairs would extend well into the hallway) or if the stairs are enclosed (new slope would cause head clearance issues with existing structure).
If the above situation applies to you don’t sweat it. The above referenced IBC code section does have an exception that may help
- An existing stairway shall not be required to comply with the requirements of Section 1009 where the existing space and construction does not allow a reduction in pitch or slope.
- Handrails otherwise required to comply with Section 1009.12 shall not be required to comply with the requirements of Section 1012.6 regarding full extension of the handrails where such extensions would be hazardous due to plan configuration.
Why the exemption for stairs (and possibly ramps, though not specifically called out)? The thinking behind the exemption is that without it, stairs that need to be replaced and are not safe will be neglected and not maintained due to the inability to bring them up to current codes. It is better to have a well maintained stair meeting an earlier code than have a poorly maintained stair that doesn’t meet current codes.