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BUILDING CONNECTION Spring 2019
A PERFORMANCE BASED DESIGN
SOLUTION – STAIR FLIGHTS
S
o where do we begin?
First, we need to remember that
the only mandatory compliance
level under the National Construction
Code (NCC) is the performance
provisions. Meeting the performance
requirements may be achieved in a
number of ways. These are developing
a Performance Based Building Solution
(PBBS) that is the equivalent to the
Deemed to Satisfy (DtS) requirements
(a benchmark approach) complying
with the performance requirements
(a first principles approach), meeting
the prescriptive DtS solutions or a
combination of these compliance
measures.
So with this in mind, what do the
performance requirements say about
flights of stairs?
In this case the relevant part of P2.5.1
requires that in order to allow people to
move safely to and within a building, the
stairway must include suitable landings
to avoid user fatigue. Thus, to achieve
this goal the DtS solution restricts
flights to 18 risers.
Now, our performance solution needs
to demonstrate that by having two
additional risers, our flight of stairs
will not cause excessive fatigue and
will be safe. I will need to demonstrate
(the burden of proof) how this will be
achieved (the standard of proof). To
demonstrate that my performance
solution meets the performance
requirement, I will consider three
factors:
1. Stairway widths
2. The number of handrails, and
3. The shape and size of handrails.
In accordance with Part A0.9 I will
assess the performance solution using
a combination of DtS comparison
(benchmarking) and expert judgement.
To achieve this, we need to identify the
minimum DtS requirements:
1. Stairway width – no minimum or
maximum widths prescribed
2. The number of handrails – one
Darryl O’Brien
provides an example of how a performance based design solutions may work in
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SURVEYANCE -
DR DARRYL O’BRIEN