The two types of stairs are differentiated by a range of factors all related to their construction and measurement. The below table simply depicts these factors:
OSHA |
IBC |
|
| Risers & Tread | 8″ open riser a 9.5″ tread |
7″ closed riser, max 4″ open gap. 11″ tread |
| Stair Width | A minimum 22″ wide stair | A minimum 44″ wide in most cases (36″ wide areas served by less than 50 people) |
| Railings & Guardrail | OSHA requires railings on open sides of stairwells and a handrail on at least on the side, preferably the right-side descending at 42″ high. | IBC Stairs require guardrails of 42″ high and handrails of 34″ high on both sides of the stairwell. |
| Balusters (vertical members in handrails) |
Space between balusters should be no more than 19″ (48 cm) apart | Space between balusters should be no more than 4″ apart |
| Landings | Both OSHA and IBC require landings at the top and bottom of the stairs, although IBC landings are larger, typically 4′ square. | IBC also requires an intermediate landing on stairwells for stairwells over 12′ high, as well as handrail extensions at the bottom landing. |
*This chart is for general reference. Regulations do change.
Regulation Reference:
Risers & Tread – OSHA stair tread requirements 90 | IBC stair width 50 | OSHA stair maximum riser height 70 | OSHA stair riser height 70
Stair Width – OSHA stair tread requirements 90
Railings and Guardrails – OSHA handrail requirements 390 | IBC handrail 320
Balusters – OSHA 1910.29(b)(2)(iii)
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