I have been building stairs, off and on, for forty years.
There are certain primes that must not be violated.
The total rise is the distance from the finished floor below to the
finished floor above.
The total run is the distance from the first riser to the flat of the
The unit rise is the division of the total rise by the highest number
that fits to the code.
The unit run is the division of the total run by the number of treads,
making sure that it is code compliant.
There are codes that get involved with this.
Unfortunately, there are too many.
I work to the current UBC and, if I have to go to court, that is my
The old rule was 7/11. The new rule varies with the jurisdiction.
There are separate rules for spiral stairs.
I can run a spiral stair in my jurisdiction that demands a 4" ball
minimum on the rail but that will allow a 6" space on an open riser.
Wish I could tell you. But I know well the feeling prior to a "building
final", that no matter how diligent/careful you've been, some arcane
interpretation of an esoteric bit of code regarding stairs could cost you a
bundle to correct, for there are few things that can be harder, or more
expensive to fix, than a set of failed stairs in a "finished" house.
On building finals I routinely make it a point to wait for the inspector,
all day if that's what it takes, so I can be present and walk along side
with *my* tape measure, and ready answers to any questions. If necessary,
I'd rather try to prevail before it makes it "on record", which causes even
the most amenable of inspectors to vigorously justify himself at appeal.
Around here, the actual framing of the stairs gets inspected at the
framing inspection. The run, rise, landings, width etc. are the
responsibility of the framing inspector.
The final guy can only reject the stairs if the final floor messes up
the rise (we've fixed a few for this problem before installing treads)
or we do something wrong with rails or balusters. Knock on wood,
we've never had one tagged.
Only the foolhardy, IMO, rely on what passed framing when it comes to stairs
in residential construction. They are indeed checked for code compliance
during the framing inspection, probably everywhere, but, being obviously
roughed in at that time, are thoroughly vetted for code and safety issues at
the building final ... and that is where any introduced, post framing
inspection non-compliance gets expen$ive.
It's also an area where it's easy to get picky if they're so inclined, and
one of the areas inspectors, particularly the relatively inexperienced who
don't come from a trades background, seem to zero in on during a final.
After all, "safety issues" are totally indefensible! ... rail
height/location, finished tread depth, riser height, clearance, baluster
spacing, winder tread compliance, etc., none of which are present during the
A lot can happen, and does ... the trim carpenter was sick one day and his
helper can't read, much less a plan; when the plans show concrete slab as FF
(by municipal edict); when the buyer changes the floor type both up and
down, or worse, just one; and with rock, and that new trim spec'd by the
buyer added, 6' 8" suddenly becomes 6' 7 1/4" ... all for starters.
IOW, it takes a good deal vigilance, experience, and taking nothing for
granted ... especially stairs that "passed" during framing. :)
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