When building a home or home
addition that includes stairs, it is important that they are built to the
National Building Code (NBC), and/or your local building code requirements.
In 1993 the NBC updated the requirements for stair treads and risers.
The NBC currently states that
stair treads must have a minimum depth of 9”. In addition the nose of the
stair tread cannot extend out more than 1” from the stair riser.
By having a minimum stair tread depth
requirement of 9”, the NBC believes that there is sufficient surface area for a
person to safely step on it. Also, by limiting the nose length to a maximum of
1” they believe that there is less likelihood of a person accidentally getting a
toe caught on the stair tread edge and tripping. Stair treads wider than 9” are
In regards to stair risers, the NBC
specifies a maximum height of 8 ¼”. By capping the stair riser height at 8 ¼”
the NBC believes that the disabled or elderly should be more capable of managing
the staircase when climbing it. Note that this is a maximum height requirement
on the stair riser. Shallower step risers are allowed, and when used in
conjunction with wider stair treads, they can produce a set of stairs that offer
a touch of elegance as well as increased functionality.
Width Requirements (Clear Width)
In residential building the NBC
and most local building codes require stairs to be a minimum of 36” wide to
allow two people to simultaneously ascend or descend them. This requirement
is referred to in the building industry as the “Clear Width”.
In addition to stair treads and riser requirements the NBC also states
that the minimum stair height to be maintained is 80” (6’ 8”).
Photo by Mark Donovan
This height needs to be maintained
throughout the entire length of the stairway.
Floating Steps and
Spiral Stair Cases
Floating steps, and in many cases
spiral stair cases, have no visible riser, however they too must meet the same 8
¼”stair riser requirement per the NBC. In regards to the stair tread depth, they
are allowed some flexibility, however in general they typically need to meet a
standard depth approximately 12-14 inches in from the narrow side.
So before you start cutting your
stair stringers make sure you follow the NBO and your local building code
requirements for stair treads and risers.
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