Q My clients would like a very wide stairway — more than 8 feet wide — leading up to their deck. Will the stairs need more than one set of handrails because of the width?

A Glenn Mathewson responds: The short answer is no. Under all editions of the International Residential Code (IRC), only one handrail on one side is ever required, regardless of the width of the stairs.

In comparison, the International Building Code (IBC) — which regulates public buildings — requires handrails on both sides of any stairway. Why care about the IBC? Because certain homeowners may choose a greater level of safety and refer to the IBC, in which case it helps to have an understanding of how the same feature in a public setting would be handled.

Under the IBC, there must also be an intermediate handrail for every 60 inches of stair width — at any place on a set of stairs, a handrail must be no more than 30 inches away. Required stair width, in turn, depends on the number of occupants expected to exit the building. Public buildings (and every space inside them) have a maximum occupant load, based on the size and occupancy type of the space (business, residential, mercantile, storage, and so on). For a non-fire-sprinkled building, the IBC requires 0.3 inch of stair width for every occupant. What this means is that even in a public facility, the occupancy load would need to be more than 100 occupants before the IBC would require a stairway wide enough to call for an intermediate handrail.

In a private home, an intermediate handrail would rarely, if ever, be needed under IBC requirements. To illustrate why: The rating for a "residential" occupancy in the IBC is one occupant (not visitors) per 200 square feet. A home and deck would need to be more than 20,000 square feet to have a large enough occupancy load to require a stairway that was 60 inches wide and needed intermediate handrails. It's not impossible to have that many occupants in a home, but it's not the norm. If your clients are entertainers, and the house or deck is very large, maybe it's worth providing additional handrails, but that's a personal choice and not a requirement under either the IBC or IRC.